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title: The barium isotopic mixture for the metal-poor subgiant star HD 140283; abstract: Context. Current theory regarding heavy element nucleosynthesis in metal-poor environments states that the r-process would be dominant. The star HD 140283 has been the subject of debate after it appeared in some studies to be dominated by the s-process. Aims. We provide an independent measure of the Ba isotope mixture using an extremely high quality spectrum and an extensive χ 2 analysis. Methods. We have acquired a very high resolution (R ≡ λ/Δλ = 95 000), very high signal-to-noise (S /N = 1110 around 4554 A, as calculated in IRAF) spectrum of HD 140283. We exploit hyperfine splitting of the Ba ii 4554 A and 4934 A resonance lines in an effort to constrain the isotope ratio in 1D LTE. Using the code ATLAS in conjunction with KURUCZ06 model atmospheres we analyse 93 Fe lines to determine the star’s macroturbulence. With this information we construct a grid of Ba synthetic spectra and, using a χ 2 code, fit these to our observed data to determine the isotopic ratio, fodd, which represents the ratio of odd to even isotopes. The odd isotopes and 138 Ba are synthesized by the r -a nds-process while the other even isotopes ( 134,136 Ba) are synthesized purely by the s-process. We also analyse the Eu lines. Results. We set a new upper limit of the rotation of HD 140283 at v sini ≤ 3. 9k m s −1 , a new upper limit on [Eu/H] −0.66. We find that, in the framework of a 1D LTE analysis, the isotopic ratios of Ba in HD 140283 indicate fodd = 0.02 ± 0.06, a purely s-process signature. This implies that observations and analysis do not validate currently accepted theory. Conclusions. We speculate that a 1D code, due to simplifying assumptions, is not adequate when dealing with observations with high levels of resolution and signal-to-noise because of the turbulent motions associated with a 3D stellar atmosphere. New approaches to analysing isotopic ratios, in particular 3D hydrodynamics, need to be considered when dealing with the levels of detail required to properly determine them. However published 3D results exacerbate the disagreement between theory and observation. | 161,900 |
title: Quasi-radial modes of rotating stars in general relativity; abstract: By using the Cowling approximation, quasi-radial modes of rotating general relativistic stars are computed along equilibrium sequences from non-rotating to maximally rotating models. The eigenfrequencies of these modes are decreasing functions of the rotational frequency. The eigenfrequency curve of each mode as a function of the rotational frequency has discontinuities, which arise from the avoided crossing with other curves of axisymmetric modes. | 161,901 |
title: Light bound states of heavy fermions; abstract: Abstract In the Standard Model, a group of heavy fermions, e.g. top quarks, can collectively strongly affect the Higgs field and create relatively long-lived bound states. If there exist new generations of fermions with masses beyond 1 TeV, strong binding of several of them can make them lighter than even a single heavy fermion. Using the mean field approximation we find multi-fermion states with masses M ∼ 5 v N ≈ 1.2 N TeV , with N = 2 , 3 , … and v = 246 GeV being the total number of heavy fermions bound together, and the Higgs VEV. These results inspire a hope that the experimental search for multi-fermions within the range of energies 2–3 Tev would either discover them, or suggest absence of new Standard Model fermions with larger masses. Possible implications related to multi-top states and baryonic asymmetry of the Universe are discussed. | 161,902 |
title: Gravitational field of compact objects in general relativity; abstract: We study some exact and approximate solutions of Einstein\u0027s equations that can be used to describe the gravitational field of astrophysical compact objects in the limiting case of slow rotation and slight deformation. First, we show that none of the standard models obtained by using Fock\u0027s method can be used as an interior source for the approximate exterior Kerr solution. We then use Fock\u0027s method to derive a generalized interior solution, and also an exterior solution that turns out to be equivalent to the exterior Hartle-Thorne approximate solution that, in turn, is equivalent to an approximate limiting case of the exact Quevedo-Mashhoon solution. As a result we obtain an analytic approximate solution that describes the interior and exterior gravitational field of a slowly rotating and slightly deformed astrophysical object. | 161,903 |
title: gAgV from chiral symmetry breaking; abstract: The ratio of the axial to vector neutron decay constants is determined via QCD sum rules. The advantageous use of the arbitrariness in the definition of the nucleon operator leads to a result which is unambiguous. The only input parameter is the value of the chiral symmetry breaking vacuum quark condensate.\\(\\langle \\bar \\Psi \\Psi \\rangle ^{{1 \\mathord{\\left/ {\\vphantom {1 3}} \\right. \\kern-\\nulldelimiterspace} 3}} = - 250 MeV\\) the output isgA/gV=1.22. | 161,904 |
title: Tau decays into four pions; abstract: We compute branching ratios and invariant mass distributions of the tau decays into four pions. The hadronic matrix elements are obtained by starting from the structure of the hadronic current in the chiral limit and then implementing low-lying resonances in the different channels. Reasonable agreement with experiment is obtained both for the τ → vτ+(4π) decay rates and the e+ e− → (4π) cross sections. Furthermore we supply an interface to use our matrix elements within the Tauola Monte-Carlo program. | 161,905 |
title: Critical Phenomena in Amorphous Ferromagnetic Alloys 1. Specific Heat Measurement; abstract: The critical phenomena of random systems have been studied by measuring specific heat of amorphous ferromagnetic alloys Fe 80- x M x P 13 C 7 (M=Ni, Mn and Cr) across the critical temperature. It has been found that the sharp phase transition observed in Fe 80 P 13 C 7 is smeared systematically by alloying, depending on the concentration and kinds of alloying atoms M. A model to explain the phenomena has been proposed. | 161,906 |
title: Internally heated convection beneath a poor conductor; abstract: We consider convection in an internally heated layer of fluid that is bounded below by a perfect insulator and above by a poor conductor. The poorly conducting boundary is modelled by a fixed heat flux. Using solely analytical methods, we find linear and energy stability thresholds for the static state, and we construct a lower bound on the mean temperature that applies to all flows. The linear stability analysis yields a Rayleigh number above which the static state is linearly unstable ($R_L$), and the energy analysis yields a Rayleigh number below which it is globally stable ($R_E$). For various boundary conditions on the velocity, exact expressions for $R_L$ and $R_E$ are found using long-wavelength asymptotics. Each $R_E$ is strictly smaller than the corresponding $R_L$ but is within 1%. The lower bound on the mean temperature is proven for no-slip velocity boundary conditions using the background method. The bound guarantees that the mean temperature of the fluid, relative to that of the top boundary, grows with the heating rate ($H$) no slower than $H^{2/3}$. | 161,907 |
title: Analysis of Flow Evolution and Thermal Instabilities in the Near-Nozzle Region of a Free Plane Laminar Jet; abstract: This work focuses on the evolution of a free plane laminar jet in the near-nozzle region. The jet is buoyant because it is driven by a continuous addition of both buoyancy and momentum at the source. Buoyancy is given by a temperature difference between the jet and the environment. To study the jet evolution, numerical simulations were performed for two Richardson numbers: the one corresponding to a temperature difference slightly near the validity of the Boussinesq approximation and the other one corresponding to a higher temperature difference. For this purpose, a time dependent numerical model is used to solve the fully dimensional Navier-Stokes equations. Density variations are given by the ideal gas law and flow properties as dynamic viscosity and thermal conductivity are considered nonconstant. Particular attention was paid to the implementation of the boundary conditions to ensure jet stability and flow rates control. The numerical simulations were also reproduced by using the Boussinesq approximation to find out more about its pertinence for this kind of flows. Finally, a stability diagram is also obtained to identify the onset of the unsteady state in the near-nozzle region by varying control parameters of momentum and buoyancy. It is found that, at the onset of the unsteady state, momentum effects decrease almost linearly when buoyancy effects increase. | 161,908 |
title: Two Local Volume Dwarf Galaxies Discovered in 21 cm Emission: Pisces A and B; abstract: We report the discovery of two dwarf galaxies, Pisces A and B, from a blind 21 cm HI search. These were the only two galaxies found via optical imaging and spectroscopy of 22 HI clouds identified in the GALFA-HI survey as dwarf galaxy candidates. They have properties consistent with being in the Local Volume ($\u003c10$ Mpc), and one has resolved stellar populations such that it may be on the outer edge of the Local Group ($\\sim 1 \\, {\\rm Mpc}$ from M31). While the distance uncertainty makes interpretation ambiguous, these may be among the faintest starforming galaxies known. Additionally, rough estimates comparing these galaxies to $\\Lambda$CDM dark matter simulations suggest consistency in number density, implying that dark matter halos likely to host these galaxies are primarily HI-rich. The galaxies may thus be indicative of a large population of dwarfs at the limit of detectability that are comparable to the faint satellites of the Local Group. Because they are outside the influence of a large dark matter halo to alter their evolution, these galaxies can provide critical anchors to dwarf galaxy formation models. | 161,909 |
title: Ten questions concerning the large-eddy simulation of turbulent flows; abstract: In the past 30 years, there has been considerable progress in the development of large-eddy simulation (LES) for turbulent flows, which has been greatly facilitated by the substantial increase in computer power. In this paper, we raise some fundamental questions concerning the conceptual foundations of LES and about the methodologies and protocols used in its application. The 10 questions addressed are stated at the end of the introduction. Several of these questions highlight the importance of recognizing the dependence of LES calculations on the artificial parameter Δ (i.e. the filter width or, more generally, the turbulence resolution length scale). The principle that LES predictions of turbulence statistics should depend minimally on Δ provides an alternative justification for the dynamic procedure. | 161,910 |
title: Some Startling Discoveries about X-Ray Bursts; abstract: Type I X-ray bursts are thought to be caused by thermonuclear flashes in the surface layers of accreting neutron stars. Recent theoretical work has shown that, contrary to what was previously thought, strongly magnetic neutron stars can produce X-ray bursts. More recently, observations with the Rossi X-Ray Timing Explorer satellite have revealed that many X-ray bursts exhibit large-amplitude brightness oscillations. In this review, we summarize the observed features of X-ray bursts and the key elements of the thermonuclear flash model of this phenomenon. We then describe the recent theoretical and observational discoveries and discuss their implications for the nature and properties of X-ray bursts. | 161,911 |
title: Focus on high energy density physics; abstract: High-energy-density physics concerns the behavior of systems at high pressure, often involving the interplay of plasma, relativistic, quantum mechanical and electromagnetic effects. The field is growing rapidly in its scope of activity thanks to advances in experimental, laser and computational technologies. This ‘focus on’ collection presents papers discussing forefront research that spans the field, providing a sense of its breadth and of the interlinking of its parts. | 161,912 |
title: Compound-cavity laser modes for arbitrary interface reflectivity.; abstract: Calculations of the longitudinal mode functions for the electric field of a compound-cavity laser show that the loss and gain coefficients are given by the Airy formula, as a function of the mode frequencies. Further, when the external cavity is longer than the gain-medium cavity, the frequency dependence of the gain is stronger than that of the loss, even when the intracavity surfaces are antireflection coated. These results provide a generalization of the oft used dielectric-bump model, in which the intracavity reflectivity has a lower bound fixed by the index mismatch at the interface between the gain medium and the external cavity. | 161,913 |
title: Scattering of 1.37 GeV α-particles by 12C; abstract: Abstract The elastic and inelastic scattering of α-particles to the lowest 2 + , 3 − and 0 + levels of 12 C is measured at an energy of 1.37 GeV. The impulse approximation using various models for the nucleon-α interaction leads to a fair agreement with experiment. It is shown that the cross sections are sensitive to the detailed description of this interaction. The best results are obtained using the free t -matrix for the scattering of a nucleon by 4 He at the same incident energy per particle (340 MeV). | 161,914 |
title: Astrophysical science metrics for next-generation gravitational-wave detectors; abstract: The second generation of gravitational-wave detectors are being built and tuned all over the world. The detection of signals from binary black holes is beginning to fulfill the promise of gravitational-wave astronomy. In this work, we examine several possible configurations for third-generation laser interferometers in existing km-scale facilities. We propose a set of astrophysically motivated metrics to evaluate detector performance. We measure the impact of detector design choices against these metrics, providing a quantitative cost-benefit analyses of the resulting scientific payoffs. | 161,915 |
title: Effect of magnetic particle chain formation on the entropy change in superparamagnetic nanocomposite systems; abstract: Abstract A simple numerical simulation model was developed to study the effect of magnetic particle-chain formation on the entropy change of a superparamagnetic nanocomposite system comprised of magnetic and nonmagnetic particles. The random deposition of these particles results in the formation of chains that have the magnetic particles in contact. The number and length distributions of these chains depend on the relationship between the number of magnetic particles and the number of nonmagnetic particles within the composite. These chains increase the equivalent size of the particles resulting in a net decrease in the entropy change of the system. This decrease in the entropy change also depends on the dilution of the composite by nonmagnetic particles. For large particles, dilution increases the entropy change; whereas for small particles, dilution reduces the entropy change. Results from this simple model provide further insight into existing theories on how to enhance the magnetocaloric effect in superparamagnetic nanocomposite systems. | 161,916 |
title: Self-propelled flexible fin in the wake of a circular cylinder; abstract: The behavior of a self-propelled flexible fin behind a circular cylinder in a uniform flow was explored using the immersed boundary method. The transverse heaving motion of the leading edge of the fin was prescribed, whereas the lateral behavior was spontaneously determined by the hydrodynamic interactions between the fin and the fluid environment. Three different behaviors were observed: propulsion upstream, drift downstream, and holding stationary at an equilibrium position. In a uniform flow, the fin could not overcome the positive net drag, and it drifted downstream. By contrast, a fin in the wake of a cylinder was propelled toward the circular cylinder during the heaving motion. The trailing edge of the fin passively fluttered along the oncoming vortices, thereby propelling the fin upstream. During the upstream propulsion behavior, the fin was propelled through the vortex cores. The fin was observed to remain stationary at a heaving frequency equal to the vortex shedding frequency, and a slaloming behavior was observed between the oncoming vortical structures. The fin was not propelled toward the cylinder during the slaloming behavior; rather, it lingered at a certain streamwise distance from the cylinder. Several equilibrium positions were dynamically determined from the interaction between the fin and the vortical fluid environment. The equilibrium position depended on the initial longitudinal position and the phase of the fin heaving motion with respect to the phase of the vortex shedding. The power input required to drive the heaving motion was reduced during the slaloming behavior. | 161,917 |
title: A supersymmetric color superconductor from holography.; abstract: We use holography to study d = 4, $$ \\mathcal{N}=4 $$\n , SU(Nc) super Yang-Mills coupled to Nf ≪ Nc quark flavors. We place the theory at finite isospin density nI by turning on an isospin chemical potential μI = Mq, with Mq the quark mass. We also turn on two R-symmetry charge densities n1 = n2. We show that the ground state is a supersymmetric, superfluid, color superconductor, namely a finite-density state that preserves a fraction of supersymmetry in which part of the global symmetries and part of the gauge symmetries are spontaneously broken. The holographic description consists of Nf D7-brane probes in AdS5 × S5. The symmetry breaking is due to the dissolution of some D3-branes inside the D7-branes triggered by the electric field associated to the isospin charge. The massless spectrum contains Goldstone bosons and their fermionic superpartners. The massive spectrum contains long-lived, mesonic quasi-particles if nI ≪ μ\n I\n 3\n , and no quasi-particles otherwise. We discuss the possibility that, despite the presence of mass scales and charge densities in the theory, conformal and relativistic invariance arise as emergent symmetries in the infrared. | 161,918 |
title: Precision mass measurements of neutron-rich Tc, Ru, Rh, and Pd isotopes; abstract: The masses of neutron-rich $^{106\\ensuremath{-}112}\\mathrm{Tc}$, $^{106\\ensuremath{-}115}\\mathrm{Ru}$, $^{108\\ensuremath{-}118}\\mathrm{Rh}$, and $^{112\\ensuremath{-}120}\\mathrm{Pd}$ produced in proton-induced fission of uranium were determined using the JYFLTRAP double Penning trap setup. The measured isotopic chains include a number of previously unmeasured nuclei. Typical precisions on the order of 10 keV or better were achieved, representing a factor of 10 improvement over earlier data. In many cases, significant deviations from the earlier measurements were found. The obtained data set of 39 masses is compared with different mass predictions and analyzed for global trends in the nuclear structure. | 161,919 |
title: Semileptonic decays of D mesons in unquenched lattice QCD; abstract: We present our preliminary results for semileptonic form factors of D mesons in unquenched lattice QCD. Simulations are carried out with n{sub f} = 2 + 1 dynamical quarks using gauge configurations generated by the MILC collaboration. For the valence quarks, we adopt an improved staggered light quark action and the clover heavy quark action. Our results for D {yields} K and D {yields} {pi} form factors at q{sup 2} = 0 are in agreement with the experimental values. | 161,920 |
title: Renormalization of the electroweak ϱ-parameter from supersymmetric particles; abstract: Abstract We compute the renormalization of the neutral-to-charged current Fermi constant ratio, arising from the new particles required in supersymmetric schemeś. We find that ϱ is insensitive to the scale of the supersymmetry mass-splitting. For a t-quark mass mt greater than this scale, the scalar-t and scalar-b contribution increases proportionally to mt2 and it is essentially equal, in sign and magnitude, to the t-, b-quark contribution. Contributions from the gaugino-higgsino-Higgs boson sector are generally of the order of a few parts in 10−3. For a class of models under consideration these results can be traced back to an approximate SU(2) symmetry which is also useful in the classification of the new particle spectrum. | 161,921 |
title: High-Altitude Particle Acceleration and Radiation in Pulsar Slot Gaps; abstract: We explore the pulsar slot gap (SG) electrodynamics up to very high altitudes, where for most relatively rapidly rotating pulsars both the standard small-angle approximation and the assumption that the magnetic field lines are ideal streamlines break down. We address the importance of the electrodynamic conditions at the SG boundaries and the occurrence of a steady state drift of charged particles across the SG field lines at very high altitudes. These boundary conditions and the deviation of particle trajectories from streamlines determine the asymptotic behavior of the scalar potential at all radii from the polar cap (PC) to near the light cylinder. As a result, we demonstrate that the steady state accelerating electric field, E∥, must approach a small and constant value at high altitude above the PC. This E∥ is capable of maintaining electrons moving with high Lorentz factors (~few × 107) and emitting curvature γ-ray photons up to nearly the light cylinder. By numerical simulations, we show that primary electrons accelerating from the PC surface to high altitude in the SG along the outer edge of the open field region will form caustic emission patterns on the trailing dipole field lines. Acceleration and emission in such an extended SG may form the physical basis of a model that can successfully reproduce some pulsar high-energy light curves. | 161,922 |
title: Effect of Sample Thickness and Operating Voltage on the Contrast of Kossel Transmission Photographs; abstract: The photographic contrast of transmission Kossel patterns is examined in terms of the voltage and thickness variables since other parameters in the contrast equation generally cannot be controlled by the investigator; they are fixed functions of the material. It is shown that there is no single thickness yielding optimum contrast. However, manipulation of the contrast equation yields an approximation to the thickness and operating voltage relationship giving Kossel transmission photographs of nearly optimum contrast. Methods for calculating this relationship for any crystal‐radiation combination are described. It is assumed throughout that the crystal is not completely free of imperfections; however, neither is the crystal assumed to be completely mosaic. | 161,923 |
title: Effects of anisotropy and boundary plates on the critical values of a porous medium heated from below; abstract: Abstract We present a linear stability analysis of Horton–Rogers–Lapwood convection in an anisotropic porous medium bounded by finite-property plates of infinite horizontal extent. Critical values for the onset of convection are obtained using a continuation method. These values are compared with experimental data. The effects of plate diffusivity, plate diffusivity, plate thickness, and anisotropy in the diffusivity and permeability of the porous medium on these critical values are explored. We find that the predicted critical values from our stability analysis agree favorably with available precision experimental measurements. | 161,924 |
title: Diffuse-charge dynamics of ionic liquids in electrochemical systems; abstract: We employ a continuum theory of solvent-free ionic liquids accounting for both short-range electrostatic correlations and steric effects (finite ion size) [Bazant et al., Phys. Rev. Lett. 106, 046102 (2011)] to study the response of a model microelectrochemical cell to a step voltage. The model problem consists of a 1-1 symmetric ionic liquid between two parallel blocking electrodes, neglecting any transverse transport phenomena. Matched asymptotic expansions in the limit of thin double layers are applied to analyze the resulting one-dimensional equations and study the overall charge-time relation in the weakly nonlinear regime. One important conclusion is that our simple scaling analysis suggests that the length scale √(λ*(D)l*(c)) accurately characterizes the double-layer structure of ionic liquids with strong electrostatic correlations where l*(c) is the electrostatic correlation length (in contrast, the Debye screening length λ*(D) is the primary double-layer length for electrolytes) and the response time of λ(D)(*3/2)L*/(D*l(c)(1/2)) (not λ*(D)L*/D* that is the primary charging time of electrolytes) is the correct charging time scale of ionic liquids with strong electrostatic correlations where D* is the diffusivity and L* is the separation length of the cell. With these two new scales, data of both electric potential versus distance from the electrode and the total diffuse charge versus time collapse onto each individual master curve in the presence of strong electrostatic correlations. In addition, the dependance of the total diffuse charge on steric effects, short-range correlations, and driving voltages is thoroughly examined. The results from the asymptotic analysis are compared favorably with those from full numerical simulations. Finally, the absorption of excess salt by the double layer creates a depletion region outside the double layer. Such salt depletion may bring a correction to the leading order terms and break down the weakly nonlinear analysis. A criterion which justifies the weakly nonlinear analysis is verified with numerical simulations. | 161,925 |
title: Extension of photon surfaces and their area: Static and stationary spacetimes; abstract: We propose a new concept, the transversely trapping surface (TTS), as an extension of the static photon surface characterizing the strong gravity region of a static/stationary spacetime in terms of photon behavior. The TTS is defined as a static/stationary timelike surface $S$ whose spatial section is a closed two-surface, such that arbitrary photons emitted tangentially to $S$ from arbitrary points on $S$ propagate on or toward the inside of $S$. We study the properties of TTSs for static spacetimes and axisymmetric stationary spacetimes. In particular, the area $A_0$ of a TTS is proved to be bounded as $A_0\\le 4\\pi(3GM)^2$ under certain conditions, where $G$ is the Newton constant and $M$ is the total mass. The connection between the TTS and the loosely trapped surface proposed by us [arXiv:1701.00564] is also examined. | 161,926 |
title: Precision measurement of the integrated luminosity of the data taken by BESIII at center-of-mass energies between 3.810 GeV and 4.600 GeV; abstract: From December 2011 to May 2014, about 5 fb(-1) of data were taken with the BESIII detector at center-ofmass energies between 3.810 GeV and 4.600 GeV to study the charmonium-like states and higher excited charmonium states. The time-integrated luminosity of the collected data sample is measured to a precision of 1% by analyzing events produced by the large-angle Bhabha scattering process. | 161,927 |
title: Gravitational waves: search results, data analysis and parameter estimation : Amaldi 10 Parallel session C2; abstract: The Amaldi 10 Parallel Session C2 on gravitational wave (GW) search results, data analysis and parameter estimation included three lively sessions of lectures by 13 presenters, and 34 posters. The talks and posters covered a huge range of material, including results and analysis techniques for ground-based GW detectors, targeting anticipated signals from different astrophysical sources: compact binary inspiral, merger and ringdown; GW bursts from intermediate mass binary black hole mergers, cosmic string cusps, core-collapse supernovae, and other unmodeled sources; continuous waves from spinning neutron stars; and a stochastic GW background. There was considerable emphasis on Bayesian techniques for estimating the parameters of coalescing compact binary systems from the gravitational waveforms extracted from the data from the advanced detector network. This included methods to distinguish deviations of the signals from what is expected in the context of General Relativity. | 161,928 |
title: Expected impact from weak reactions with light nuclei in core-collapse supernova simulations; abstract: We study the role of light nuclear clusters in simulations of core-collapse supernovae. Expressions for the reaction rates are developed for a large selection of charged current absorption and scattering processes with light clusters. Medium modifications are taken into account at the mean-field level. We explore the possible impact on the supernova dynamics and the neutrino signal during the mass accretion phase prior to the possible explosion onset as well as during the subsequent protoneutron star deleptnoization after the explosion onset has been launched. | 161,929 |
title: $D_S$ Mesons in Asymmetric Hot and Dense Hadronic Matter; abstract: The in-medium properties of mesons are investigated within the framework of an effective hadronic model, which is a generalization of a chiral model, to , in order to study the interactions of the charmed hadrons. In the present work, the mesons are observed to experience net attractive interactions in a dense hadronic medium, hence reducing the masses of the and mesons from the vacuum values. While this conclusion holds in both nuclear and hyperonic media, the magnitude of the mass drop is observed to intensify with the inclusion of strangeness in the medium. Additionally, in hyperonic medium, the mass degeneracy of the mesons is observed to be broken, due to opposite signs of the Weinberg-Tomozawa interaction term in the Lagrangian density. Along with the magnitude of the mass drops, the mass splitting between and mesons is also observed to grow with an increase in baryonic density and strangeness content of the medium. However, all medium effects analyzed are found to be weakly dependent on isospin asymmetry and temperature. We discuss the possible implications emanating from this analysis, which are all expected to make a significant difference to observables in heavy ion collision experiments, especially the upcoming Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR), GSI, where matter at high baryonic densities is planned to be produced. | 161,930 |
title: Characterization of Cs vapor cell coated with octadecyltrichlorosilane using coherent population trapping spectroscopy; abstract: We report the realization and characterization using coherent population trapping (CPT) spectroscopy of an octadecyltrichlorosilane (OTS)-coated centimeter-scale Cs vapor cell. The dual-structure of the resonance lineshape, with presence of a narrow structure line at the top of a Doppler-broadened structure, is clearly observed. The linewidth of the narrow resonance is compared to the linewidth of an evacuated Cs cell and of a buffer gas Cs cell of similar size. The Cs-OTS adsorption energy is measured to be (0.42 ± 0.03) eV, leading to a clock frequency shift rate of 2.7 × 10−9/K in fractional unit. A hyperfine population lifetime, T1, and a microwave coherence lifetime, T2, of 1.6 and 0.5 ms are reported, corresponding to about 37 and 12 useful bounces, respectively. Atomic-motion induced Ramsey narrowing of dark resonances is observed in Cs-OTS cells by reducing the optical beam diameter. Ramsey CPT fringes are detected using a pulsed CPT interrogation scheme. Potential applications of the Cs-OTS cell ... | 161,931 |
title: The oscillating dark energy: future singularity and coincidence problem; abstract: Abstract We consider the oscillating dark energy with periodic equation of state in two equivalent formulations: ideal fluid or scalar–tensor theory. It is shown that such dark energy suggests the natural way for the unification of early-time inflation with late-time acceleration. We demonstrate how it describes the transition from deceleration to acceleration or from non-phantom to phantom era and how it solves the coincidence problem. The occurrence of finite-time future singularity for the oscillating (phantom) universe is also investigated. | 161,932 |
title: High energy variability of 3C 273 during the AGILE multiwavelength campaign of December 2007-January 2008; abstract: Context. We report the results of a 3-week multi-wavelength campaign targeting the flat spectrum radio quasar 3C 273 carried out with the AGILE gamma-ray mission, covering the 30 MeV–50 GeV and 18–60 keV, the REM observatory (covering the near-IR and optical), Swift (nearUV/Optical, 0.2–10 keV and 15–50 keV), INTEGRAL (3–200 keV) and Rossi XTE (2–12 keV). This is the first observational campaign including gamma-ray data, after the last EGRET observations, more than 8 years ago. Aims. This campaign has been organized by the AGILE team with the aim of observing, studying and modelling the broad band energy spectrum of the source, and its variability on a week timescale, testing the emission models describing the spectral energy distribution of this source. Methods. Our study was carried out using simultaneous light curves of the source flux from all the involved instruments, in the different energy ranges, to search for correlated variability. Then a time-resolved spectral energy distribution was used for a detailed physical modelling of the emission mechanisms. Results. The source was detected in gamma-rays only in the second week of our campaign, with a flux comparable to the level detected by EGRET in June 1991. We found an indication of a possible anti-correlation between the emission at gamma-rays and at soft and hard X-rays, supported by the complete set of instruments. Instead, optical data do not show short term variability, as expected for this source. Only in two preceding EGRET observations (in 1993 and 1997) 3C 273 showed intra-observation variability in gamma-rays. In the 1997 observation, flux variation in gamma-rays was associated with a synchrotron flare. The energy-density spectrum with almost simultaneous data partially covers the regions of synchrotron emission, the big blue bump, and the inverse-Compton. We adopted a leptonic model to explain the hard X/gamma-ray emissions, although from our analysis hadronic models cannot be ruled out. In the adopted model, the soft X-ray emission is consistent with combined synchrotron-self Compton and external Compton mechanisms, while hard X and gamma-ray emissions are compatible with external Compton from thermal photons of the disk. Under this model, the time evolution of the spectral energy distribution is well interpreted and modelled in terms of an acceleration episode of the electron population, leading to a shift in the inverse Compton peak towards higher energies. | 161,933 |
title: Optical and IR Photometry of Globular Clusters in NGC1399: Evidence for Color-Metallicity Nonlinearity; abstract: We combine new Wide Field Camera~3 IR Channel (WFC3/IR) F160W (H) imaging data for NGC1399, the central galaxy in the Fornax cluster, with archival F475W (g), F606W (V), F814W (I), and F850LP (z) optical data from the Advanced Camera for Surveys (ACS). The purely optical g-I, V-I, and g-z colors of NGC1399\u0027s rich globular cluster (GC) system exhibit clear bimodality, at least for magnitudes $I_814 \u003e 21.5$. The optical-IR I-H color distribution appears unimodal, and this impression is confirmed by mixture modeling analysis. The V-H colors show marginal evidence for bimodality, consistent with bimodality in V-I and unimodality in I-H. If bimodality is imposed for I-H with a double Gaussian model, the preferred blue/red split differs from that for optical colors; these \"differing bimodalities\" mean that the optical and optical-IR colors cannot both be linearly proportional to metallicity. Consistent with the differing color distributions, the dependence of I-H on g-I for the matched GC sample is significantly nonlinear, with an inflection point near the trough in the g-I color distribution; the result is similar for the I-H dependence on g-z colors taken from the ACS Fornax Cluster Survey. These g-z colors have been calibrated empirically against metallicity; applying this calibration yields a continuous, skewed, but single-peaked metallicity distribution. Taken together, these results indicate that nonlinear color-metallicity relations play an important role in shaping the observed bimodal distributions of optical colors in extragalactic GC systems. | 161,934 |
title: Are there two regimes in strongly rotating turbulence; abstract: We describe numerical experiments of freely decaying, rapidly rotating turbulence in which the Rossby number varies from Ro = O(1) down to Ro ∼ 0.02. Our central premise is that there exists two distinct dynamical regimes; one for Ro \u003e 0.3 → 0.4, which is typical of most laboratory experiments, and another corresponding to Ro 0.3 → 0.4 is reported in Baqui and Davidson [“A phenomenological theory of rotating turbulence,” Phys. Fluids 27, 025107 (2015)] and is characterised by: (i) a growth of the parallel integral scale according to l|| ∼ l⊥Ωt; (ii) a dissipation law which is quite different from that predicted by weak-turbulence theories, specifically e = βu3/l|| where the pre-factor β is a constant of order unity; and (iii) an inertial-range energy spectrum for both the parallel and perpendicular wavenumbers which scales as k−5/3, a scaling that has nothing to do with Kolmogorov’s law in non-rotating turbulence. (Here, l|| is the inte... | 161,935 |
title: NMR in solid D2 near the orientational ordering transition; abstract: A study of the NMR lineshapes in solid D2 for various concentrations C of (J = 1) molecules is presented. Below the rotational ordering temperature Tλ (C), the lineshape has two doublets. The outer one, attributed to the J = 1 molecules, has a splitting of about 75 kHz for T ⪡ Tλ. This splitting, which is proportional to the order parameter, was studied as a function of temperature. For the region 0.02 \u003c 1 - T/Tλ \u003c 0.08, the data could be fitted to a power law (1 - T/Tλ)β with β ≅ 0.33. The inner doublet was attributed to J = 0 molecules. Its splitting is proportional to Tλ (C) and is extrapolated to 8.5 kHz for C = 1 in good agreement with the prediction of Harris. | 161,936 |
title: Quantum fluctuations in second-harmonic light generation; abstract: Abstract Second-harmonic light generation (SHLG) is analyzed from the viewpoint of the photon statistics of the fundamental and generated beams versus the path traversed by the two waves in the medium. The calculations lead to an anti-bunching effect for coherent incident light. | 161,937 |
title: Critical Phenomena Near Bifurcations in Nonequilibrium Systems; abstract: The usual deterministic description of spatially-extended nonlinear dissipative systems far from equilibrium yields a sharp bifurcation point at a crtical value R=Rc of the control parameter where the system makes a transition from the spatially uniform ground state to a state with spatial variation. However, when the effect of thermal noise is considered, then even below the bifurcation there are fluctuations of the macroscopic variables away from the uniform state and the relevant fields, although they have zero mean, have a positive mean square. Here we review measurements of the properties of these fluctuations. In the case of Rayleigh–Benard convection (RBC) in common fluids, fluctuation amplitudes are small and the exponent of the powerlaw which describes their mean square has its classical (mean-field) value γMF=1/2 in experimentally accessible parameter ranges. However, for RBC of a fluid near its liquid-gas critical point fluctuation amplitudes are much larger and nonlinear interactions between them yield a first-order transition as predicted by Swift and Hohenberg. Electroconvection in nematic liquid crystals (NLC) does not belong to the same universality class as RBC, and fluctuation interactions leave the bifurcation supercritical; but the critical behavior is renormalized. | 161,938 |
title: KL − KS mass difference and quark models; abstract: Abstract The matrix element 〈 K 0 |H W | K 0 〉 is calculated in the quark MIT bag model and in several relativized versions of the quark harmonic-oscillator models for hadrons. The results of the MIT bag model depend strongly on the particular choice of parameters, while the results of the harmonic-oscillator model are relatively stable on the variation of model parameters. The harmonic-oscillator model which takes into account the c.m. motion (the RHO model) is in reasonably good agreement with the vacuum-saturation value. | 161,939 |
title: An improved phase measurement method of integrated pulse profile for pulsar; abstract: Integrated profile is one of the basic characteristic of X-ray pulsar. Gaussian function fit is used to model the components of X-ray pulsar profile, and it is combined with Poisson distribution model of X-ray pulsar to analyze Cramer-Rao low bound (CRLB) of phase, phase rate estimation and relation between CRLB and profile components. Then, a time domain method using minimum entropy is proposed for profile phase and phase rate estimation, and its effectiveness is explained using simulation examples. | 161,940 |
title: Search for stable heavy massive particles of positive integral charge; abstract: Abstract A search has been made for stable heavy massive particles of positive integral charge in deuterium samples. The concentration of such particles in the mass range 6–16 atomic mass units is estimated to be less than 3 × 10 −18 per hydrogen atom in ordinary water. | 161,941 |
title: Properties of platinum isotopes in framework of particle rotor model and IBM; abstract: Abstract We introduce a model that consists of an axially symmetric core plus two particles occupying the lowest two sublevels i 13 / 2 orbital. The exact solution of this model has been calculated by diagonalizing 4 × 4 matrices. By fitting the experimental single particle spectrum in these nuclei, a new set of Nilsson parameters and deformation parameter are proposed. Since the excitation energy spectrum of the core is very difficult to simulate through any simple energy angular momentum relationship, we use the variable moment of inertia (VMI) core formalism. The calculated kinematic moment of inertia, rotational frequency and the component of angular momentum along an axis perpendicular to the symmetry axis reproduce quite well the backbending of the yrast band in 180–192Pt. Nuclei exhibit an anomaly along the yrast line around angular momentum 10 + to 12 + . An apparent change of structure occurs when transiting from 186Pt to 188Pt. It is more appropriate to describe Pt nuclei within the IBM Hamiltonian based on the intrinsic coherent state to generate the potential energy surfaces (PES\u0027s) to identify the shape transition. The equilibrium values of shape parameter β are obtained by minimizing the PES and also the location of the critical points are obtained. The isotopic chain 180–192Pt evolves from prolate to oblate shapes between 186Pt (prolate) and 188Pt (oblate). The PES\u0027s for both 188,190Pt are γ-soft having the minimum on the oblate side. | 161,942 |
title: Flavor symmetry in two body decays of bottom mesons; abstract: Dominant decays of bottom mesons into two pseudoscalars are studied in the framework of the six-quark model of the weak interactions of Kobayashi and Maskawa. Some simpleSU (3) relations between the amplitudes are obtained without using any dynamical assumptions. | 161,943 |
title: An Explanation for the Undetection of Radio Pulsar in Supernova 1987A; abstract: Supernova 1987A is a core collapse supernova in the Large Magellanic Cloud, inside which the product is most likely a neutron star. Despite the most sensitive available detection instruments from radio to gamma-ray wavebands being exploited in the pass thirty years, there have not yet been any pulse signals detected. By considering the density of the medium plasma in the remnant of 1987A, we find that the plasma cut-off frequency is approximately 7 GHz, a value higher than the conventional observational waveband of radio pulsars. As derived, with the expansion of the supernova remnant, the radio signal will be detected in 2073 A.D. at 3 GHz. | 161,944 |
title: Rummukainen-Gottlieb's formula on two-particle system with different mass; abstract: A proposal by L\\\"uscher enables us to extract the elastic scattering phases from two-particle energy spectrum in a cubic box using lattice simulations. Rummukainen and Gottlieb further extend it to the moving frame, which is devoted to the system of two identical particles. In this work, we generalize Rummukainen-Gottlieb\u0027s formula to the generic two-particle states where two particles are explicitly distinguishable, namely, the masses of the two particles are different. Their relations with the elastic scattering phases of two-particle energy spectrum in the continuum are obtained for both ${C}_{4v}$ and ${C}_{2v}$ symmetries. Our analytical results will be very helpful for the study of some resonances, such as kappa, vector kaon, and so on. | 161,945 |
title: Multiferroic BiMnO3 thin films with double SrTiO3 buffer layers; abstract: High quality BiMnO3 thin films with double SrTiO3 buffer layers were fabricated on Pt∕Ti∕SiO2∕Si and SrTiO3 substrates, in which SrTiO3 buffer layers were used to reduce leakage current in BiMnO3 thin films. The SrTiO3 buffer layers had a thickness of about 5nm obtained from the fitting of ellipsometer data, which gave the remarkable enhancement in leakage current. BiMnO3 thin films exhibited the ferromagnetic transition with the Curie temperature of about 105K. The Pt∕SrTiO3∕BiMnO3∕SrTiO3∕Pt and SrRuO3∕SrTiO3∕BiMnO3∕SrTiO3∕SrRuO3 capacitors showed good ferroelectric properties with the remanent polarization of about 9 and 16μC∕cm2, respectively. | 161,946 |
title: Irreversible thermodynamics of the universe in \(\varvec{f}(R)\) gravity; abstract: In this study, the irreversible thermodynamics of the universe in the framework of f(R) gravity has been studied following standard Eckart theory of non-equilibrium thermodynamics. For a spatially flat universe, validity of GSLT and thermodynamic equilibrium have been examined both for apparent and event horizon as bounding horizons.The general result has been verified for exponential models of f(R) gravity and it is shown that GSLT holds on both apparent and event horizon, but thermodynamic equilibrium does not hold on event horizon. | 161,947 |
title: Probing a slepton Higgs on all frontiers; abstract: Author(s): Biggio, C; Dror, JA; Grossman, Y; Ng, WH | Abstract: © 2016, The Author(s). We study several aspects of supersymmetric models with a U(1)R symmetry where the Higgs doublet is identified with the superpartner of a lepton. We derive new, stronger bounds on the gaugino masses based on current measurements, and also propose ways to probe the model up to scales of O(10 TeV) at future e+e− colliders. Since the U(1)R symmetry cannot be exact, we analyze the effects of R-symmetry breaking on neutrino masses and proton decay. In particular, we find that getting the neutrino mixing angles to agree with experiments in a minimal model requires a UV cutoff for the theory at around 10 TeV. | 161,948 |
title: Star formation and gas in the minor merger UGC 10214; abstract: UGC 10214 is a minor merger in which a dwarf galaxy has interacted with a large spiral galaxy $\\sim$250 Myr ago and produced a perturbed disk and a giant tidal tail. We use a multiwavelength dataset in order to study the present and past star formation rate (SFR) and its relation to the gas and stellar mass at a spatial resolution down to 4 kpc. UGC 10214 is a very massive (stellar mass $M_{{\\rm \\star}}$ = $1.28\\times 10^{11}$$M_\\odot$) galaxy with a low gas fraction ($M_{{\\rm gas}}$/$M_{{\\rm \\star}}$ = 0.24), a high molecular gas fraction ($M_{{\\rm H}_2}$/$M_{\\rm HI}$ = 0.4) and a modest SFR (2-5 $M_\\odot$ yr$^{-1}$). The comparison of the molecular gas mass and current SFR gives a molecular gas depletion time of about $\\sim$ 2 Gyr (based on H$\\alpha$), comparable to those of normal spiral galaxies. Both from a comparison of the H$\\alpha$ emission, tracing the current SFR, and far-ultraviolet (FUV) emission, tracing the recent SFR during the past tens of Myr, as well as from spectral energy distribution (SED) fitting with CIGALE, we find that the SFR has increased by a factor of about 2-3 during the recent past. This increase is particularly noticeable in the centre of the galaxy. A pixel-to-pixel comparison of the SFR, molecular gas mass and stellar mass shows that the central region has had a depressed FUV-traced SFR, both compared to the molecular gas and the stellar mass, whereas the H$\\alpha$-traced SFR shows a normal level. The atomic and molecular gas distribution is asymmetric, but the position-velocity diagram along the major axis shows a pattern of regular rotation. We conclude that the minor merger has most likely caused variations in the SFR in the past resulting in a moderate increase of the SFR, but it has not perturbed the gas significantly so that the molecular depletion time remains normal. | 161,949 |
title: An infrared pyroelectric detector improved by cool isostatic pressing with cup-shaped PZT thick film on silicon substrate; abstract: Abstract In this paper, we presented a new pyroelectric detector with back to back silicon cups and micro-bridge structure. The PZT thick film shaped in the front cup was directly deposited with designed pattern by electrophoresis deposition (EPD). Pt/Ti Metal film, which was fabricated by standard photolithography and lift-off technology, was sputtered to connect the top electrode and the bonding pad. The cold isostatic press (CIP) treatment could be applied to improve the pyroelectric properties of PZT thick film. The infrared (IR) properties the CIP-optimized detector were measured. The voltage responsivity ( R V ) was 4.5 × 10 2 V/W at 5.3 Hz, the specific detectivity ( D * ) was greater than 6.34 × 10 8 cm Hz 1/2 W −1 (frequency \u003e 110 Hz), and the thermal time constant was 51 ms, respectively. | 161,950 |
title: Rotation of Giant Stars; abstract: The internal rotation of post-main sequence stars is investigated, in response to the convective pumping of angular momentum toward the stellar core, combined with a tight magnetic coupling between core and envelope. The spin evolution is calculated using model stars of initial mass 1, 1.5 and $5\\,M_\\odot$, taking into account mass loss on the giant branches. We also include the deposition of orbital angular momentum from a sub-stellar companion, as influenced by tidal drag along with the excitation of orbital eccentricity by a fluctuating gravitational quadrupole moment. A range of angular velocity profiles $\\Omega(r)$ is considered in the envelope, extending from solid rotation to constant specific angular momentum. We focus on the back reaction of the Coriolis force, and the threshold for dynamo action in the inner envelope. Quantitative agreement with measurements of core rotation in subgiants and post-He core flash stars by Kepler is obtained with a two-layer angular velocity profile: uniform specific angular momentum where the Coriolis parameter ${\\rm Co} \\equiv \\Omega \\tau_{\\rm con} \\lesssim 1$ (here $\\tau_{\\rm con}$ is the convective time); and $\\Omega(r) \\propto r^{-1}$ where ${\\rm Co} \\gtrsim 1$. The inner profile is interpreted in terms of a balance between the Coriolis force and angular pressure gradients driven by radially extended convective plumes. Inward angular momentum pumping reduces the surface rotation of subgiants, and the need for a rejuvenated magnetic wind torque. The co-evolution of internal magnetic fields and rotation is considered in Kissin \u0026 Thompson, along with the breaking of the rotational coupling between core and envelope due to heavy mass loss. | 161,951 |
title: Frequency-locking of a CW dye laser to some absorption lines of a neon discharge by a Faraday filter; abstract: Abstract Single-mode oscillations of a CW dye laser at the center of five absorption lines from the 1s states to the 2p states of neon were obtained by means of a neon discharge Faraday filter, without any other frequency-selective elements. The most striking thing observed is that saturated absorption takes place at the center of several absorption lines in a Faraday filter, in addition to optical rotation. | 161,952 |
title: Periodic soliton trains and informational code structures in an improved soliton model for biomembranes and nerves.; abstract: Many experiments have shown that the action potential propagating in a nerve fiber is an electromechanical density pulse. A mathematical model proposed by Heimburg and Jackson is an important step in explaining the propagation of electromechanical pulses in nerves. In this work, we consider the dynamics of modulated waves in an improved soliton model for nerve pulses. Application of the reductive perturbation method on the resulting generalized Boussinesq equation in the low-amplitude and weak damping limit yields a damped nonlinear Schrodinger equation that is shown to admit soliton trains. This solution contains an undershoot beneath the baseline (\"hyperpolarization\") and a \"refractory period,\" i.e., a minimum distance between pulses, and therefore it represents typical nerve profiles. Likewise, the linear stability of wave trains is analyzed. It is shown that the amplitude of the fourth-order mixed dispersive term introduced here can be used to control the amount of information transmitted along the nerve fiber. The results from the linear stability analysis show that, in addition to the main periodic wave trains observed in most nerve experiments, five other localized background modes can copropagate along the nerve. These modes could eventually be responsible for various fundamental processes in the nerve, such as phase transitions and electrical and mechanical changes. Furthermore, analytical and numerical analyses show that increasing the fourth-order mixed dispersion coefficient improves the stability of the nerve signal. | 161,953 |
title: Kaluza-Klein gravity; abstract: We review higher-dimensional unified theories from the general relativity, rather than the particle physics side. Three distinct approaches to the subject are identified and contrasted: compactified, projective and noncompactified. We discuss the cosmological and astrophysical implications of extra dimensions, and conclude that none of the three approaches can be ruled out on observational grounds at the present time. | 161,954 |
title: Twenty years of particle image velocimetry; abstract: The development of the method of particle image velocimetry (PIV) is traced by describing some of the milestones that have enabled new and/or better measurements to be made. The current status of PIV is summarized, and some goals for future advances are addressed. | 161,955 |
title: Constraining Primordial Non-Gaussianity with High-Redshift Probes; abstract: We present an analysis of the constraints on the amplitude of primordial non-Gaussianity of local type described by the dimensionless parameter fNL. These constraints are set by the auto-correlation functions (ACFs) of two large scale structure probes, the radio sources from NRAO VLA Sky Survey (NVSS) and the QSO catalogue of Sloan Digital Sky Survey Release Six (SDSS DR6 QSOs), as well as by their cross-correlation functions (CCFs) with the cosmic microwave background (CMB) temperature map (Integrated Sachs-Wolfe effect). Several systematic effects that may affect the observational estimates of the ACFs and of the CCFs are investigated and conservatively accounted for. Our approach exploits the large-scale scale-dependence of the non-Gaussian halo bias. The derived constraints on {fNL} coming from the NVSS CCF and from the QSO ACF and CCF are weaker than those previously obtained from the NVSS ACF, but still consistent with them. Finally, we obtain the constraints on fNL = 53±25 (1 σ) and fNL = 58±24 (1 σ) from NVSS data and SDSS DR6 QSO data, respectively. | 161,956 |
title: Third-order statistics and the dynamics of strongly anisotropic turbulent flows; abstract: Anisotropy is induced by body forces and/or mean large-scale gradients in turbulent flows. For flows without energy production, the dynamics of second-order velocity or second-order vorticity statistics are essentially governed by triple correlations, which are at the origin of the anisotropy that penetrates towards the inertial range, deeply altering the cascade and the eventual dissipation process, with a series of consequences on the evolution of homogeneous turbulence statistics: in the case of rotating turbulence, the anisotropic spectral transfer slaves the multiscale anisotropic energy distribution; nonlinear dynamics are responsible for the linear growth in terms of Ωt of axial integral length-scales; third-order structure functions, derived from velocity triple correlations, exhibit a significant departure from the 4/5 Kolmogorov law. We describe all these implications in detail, starting from the dynamical equations of velocity statistics in Fourier space, which yield third-order correlations at... | 161,957 |
title: Coupling functions for muon hodoscopes; abstract: The specific features of calculating the coupling functions for muon hodoscopes are considered. The results of calculating the main coupling functions for three versions of the primary spectra of cosmic rays (CR)—galactic CR, solar CR during proton events, and galactic CR variations during Forbush decreases-are presented. The calculations have been performed based on modeling CR propagation through the Earth’s atmosphere using the CORSIKA code. The mean and median CR energies, contributing to the muon detector counting rate, have been calculated for different zenith angles. It has been shown that muon detectors are sensitive to different energies of primary CRs for different directions. | 161,958 |
title: Spectral Function Analysis on Spin Dynamics in Double-Exchange Systems with Randomness; abstract: Spin excitation spectrum is studied in the double-exchange model with randomness. Applying the spin wave approximation and the spectral function analysis, we examine excitation energy and linewidth using analytical as well as numerical methods. For a small wave number q ∼0, the excitation energy is cosine-like and the linewidth shows q -linear behavior. This indicates that the spin excitation becomes incoherent or localized near q = 0. Crossover takes place to the marginally coherent regime where both the excitation energy and the linewidth are proportional to q 2 . The incoherence is due to local fluctuations of the kinetic energy of electrons. Comparison with experimental results in colossal magnetoresistance manganites suggests that spatially-correlated or mesoscopic-scale fluctuations are more important in real compounds than local or atomic-scale ones. | 161,959 |
title: Critical behavior of the in-plane weak ferromagnet Sr2IrO4; abstract: Abstract Critical behavior of the single-layered Sr2IrO4, which exhibits weak ferromagnetism in the ab plane, is investigated by the bulk magnetization study. Critical exponents β = 0.284 ± 0.008 and γ = 1.726 ± 0.004 with the critical temperature TC=230.8±0.9 are obtained by the Kouvel–Fisher method, and δ = 4.443 ± 0.008 is generated by the critical isotherm analysis at TC=231 K. The obtained critical exponents of Sr2IrO4 are close to prediction of the theoretical model with { d : n } = { 2 : 1 } (where d is the partial dimensionality and n is the spin dimensionality), which indicates one-dimensional ferromagnetic interaction in the two-dimensional layered material. On the other hand, the critical exponents lie between the prediction of long-range and short-range models, indicating that the short-range Heisenberg interaction alone cannot totally describe the critical behavior. It is suggested that the Dzialoshinsky–Moriya interaction caused by rotation of the octahedra and the symmetric anisotropy result into a lower spatial short-range interaction, which competes with the long-range interaction caused by expansion of 5d orbits. | 161,960 |
title: Incompressible lattice Boltzmann model for axisymmetric flows through porous media; abstract: In this paper, an axisymmetric LBE model for incompressible flows through porous media is proposed. In this model, the influence of density change caused by large pressure difference can be overcome by replacing density distribution function with pressure distribution function. A more simple processing format for external force is introduced so as to make the involved method in this paper more perfect. The coupling between flow velocity and pressure also can be significantly reduced when calculating the macroscopic quantities. Good agreement between the analytical solution and numerical results is also obtained based on this model and it also can provide guidance for other problem with such complicated force forms. | 161,961 |
title: The energy spectrum of anomalous X-ray pulsars and soft gamma-ray repeaters; abstract: Assuming that AXPs and SGRs accrete matter from a fallback disk, we attempt to explain both the soft and the hard X-ray emission as the result of the accretion process. We also attempt to explain their radio emission or the lack of it. We test the hypothesis that the power-law, hard X-ray spectra are produced in the accretion flow mainly by bulk-motion Comptonization of soft photons emitted at the neutron star surface. Fallback disk models invoke surface dipole magnetic fields of $10^{12} - 10^{13}$ G, which is what we assume here. Unlike normal X-ray pulsars, for which the accretion rate is highly super-Eddington, the accretion rate is approximately Eddington in AXPs and SGRs and thus the bulk-motion Comptonization operates efficiently. As an illustrative example we reproduce both the hard and the soft X-ray spectra of AXP 4U 0142+61 well using the XSPEC package compTB. Our model seems to explain both the hard and the soft X-ray spectra of AXPs and SGRs, as well as their radio emission or the lack of it, in a natural way. It might also explain the short bursts observed in these sources. On the other hand, it cannot explain the giant X-ray outbursts observed in SGRs, which may result from the conversion of magnetic energy in local multipole fields. | 161,962 |
title: Effect of a fossil magnetic field on the structure of a young Sun; abstract: We study the impact of a fossil magnetic field on the physical quantities which describe the structure of a young Sun of 500 Myr. We consider for the first time a non-force-free field composed of a mixture of poloidal and toroidal magnetic fields and propose a specific configuration to illustrate our purpose. In this paper, we estimate the relative role of the different terms which appear in the modified stellar structure equations. We note that the Lorentz tension plays a non-negligible role in addition to the magnetic pressure. This is interesting because most of the previous stellar evolution codes ignored that term and the geometry of the field. The solar structure perturbations are, as already known, small and consequently we have been able to estimate each term semi-analytically. We develop a general treatment to calculate the global modification of the structure and of the energetic balance. We also estimate the gravitational multipolar moments associated with the presence of a fossil large-scale magnetic field in radiative zone. The values given for the young Sun help the future implementation in stellar evolution codes. This work can be repeated for any other field configuration and prepares the achievement of a solar magnetohydrodynamic model where we will follow the transport of such field on secular time-scales and the associated transport of momentum and chemicals. The described method will be applied at the present Sun and the results will be compared with the coming balloon or space measurements. | 161,963 |
title: Decay laws for three-dimensional magnetohydrodynamic turbulence; abstract: Decay laws for three-dimensional magnetohydrodynamic turbulence are obtained from high-resolution numerical simulations using up to 512^3 modes.... | 161,964 |
title: BSM Higgs physics in the exclusive forward proton mode at the LHC; abstract: We investigate the prospects for Central Exclusive Diffractive (CED) production of BSM Higgs bosons at the LHC using forward proton detectors installed at 220 m and 420 m distance around ATLAS and/or CMS. We update a previous analysis for the MSSM taking into account improvements in the theoretical calculations and the most recent exclusion bounds from the Tevatron. We extend the MSSM analysis to new benchmark scenarios that are in agreement with the cold dark matter relic abundance and other precision measurements. We analyze the exclusive production of Higgs bosons in a model with a fourth generation of fermions. Finally, we comment on the determination of Higgs spin–parity and coupling structures at the LHC and show that the forward proton mode could provide crucial information on the \\(\\mathcal{CP}\\) properties of the Higgs bosons. | 161,965 |
title: Vacancy-induced enhancement of magnetic interactions in "Ca, Na…-doped lanthanum manganites; abstract: Structural, electric, and magnetic properties of the bulk polycrystalline samples with nominal composition La0.7Ca0.3−xNaxMnO3 (x=0−0.10) have been investigated in the work. As follows from the results of chemical and x-ray structural analyses, the increase in x brings about the rise in the number of structural vacancies in both lanthanum and oxygen sublattices. The influence of the variation of the vacancy number on peculiar features of the transition from ferromagnetic metallic state to paramagnetic state with activated conductivity has been studied in detail. The conclusion is made that the rise in the number of structural vacancies gives rise not only to the enhancement of magnetic inhomogeneity and broadening of the magnetic transition, but also to the increase in the temperature of magnetic transition. It is demonstrated that the changes in magnetic parameters also result in the increase of the temperatures of resistivity and magnetoresistance peaks as well as in the change of the character of the t... | 161,966 |
title: Scintillation of Radio Sources: The Role of Caustics; abstract: Scintillation of a radio source can be treated relatively simply by making the stationary phase point (SPP) approximation to the Fresnel-Kirchhoff integral, but the range of validity of the SPP approximation is not well determined. We identify three idealized models for the phase variation for which there are accurate approximations (\"exact\" results), and we compare these exact results with the SPP approximations to them. For two of the models—the coherent wave (CW) model and the single-phase pulse model—the integral can be evaluated in closed form, involving infinite sums that can be truncated without loss of accuracy, and for the third model the integral is determined accurately using fast Fourier transforms. We find that for the majority of observer positions the SPP method gives excellent results. However, near a caustic the SPP approximation breaks down and can be positively misleading. We find that for moderate screen strengths the putative caustic lines are the loci of regions where the intensity oscillates rapidly. The conventional caustic behavior is exhibited only as an envelope of rapid diffractive fluctuations for sufficiently large phase variations, with amplitude 0 103 rad. We discuss a suggested application of the single phase pulse to extreme scattering events and compare our exact results with existing models that are based on geometric optics. We also suggest that the CW model might be applied to the highly localized, anisotropic turbulence inferred for intraday variable sources and for the secondary spectra in pulsars. | 161,967 |
title: Moisture transfer by turbulent natural convection; abstract: We present an experimental and numerical study of natural convection with moist air as convecting fluid. By simplifying the system as two-component convection, an experimental method is proposed for indirectly measuring the moisture transfer rates in buoyancy-driven flows. We verify the results using direct numerical simulations. It is found that the non-dimensionalized transfer rates for both sensible heat ( $Nu_{T}$\n ) and water vapour ( $Nu_{e}$\n ) are essentially determined by a generalized Grashof number $Gr$\n (the ratio of combined buoyancy generated by the imposed temperature and vapour pressure gradients to viscous force), and are only weakly dependent on the buoyancy ratio $\\unicode[STIX]{x1D6EC}$\n (the ratio of buoyancy induced by temperature variation to that due to vapour pressure variation). Moreover, we show that the full set of control parameters $\\{Gr,\\unicode[STIX]{x1D6EC},Pr,Sc\\}$\n is more suitable than other choices for characterizing the two-component system under investigation. As a special case, the Schmidt number dependence for passive scalar transport rates in buoyancy-driven flows is also deduced. | 161,968 |
title: Nonperturbative models of quark stars in $f$(R) gravity; abstract: Abstract Quark star models with realistic equation of state in nonperturbative f ( R ) gravity are considered. The mass-radius relation for f ( R ) = R + α R 2 model is obtained. Considering scalar curvature R as an independent function, one can find out, for each value of central density, the unique value of central curvature for which one has solutions with the required asymptotic R → 0 for r → ∞ . In other words, one needs a fine-tuning for R to achieve quark stars in f ( R ) gravity. We consider also the analogue description in corresponding scalar-tensor gravity. The fine-tuning on R is equivalent to the fine-tuning on the scalar field ϕ in this description. For distant observers, the gravitational mass of the star increases with increasing α ( α \u003e 0 ) but the interpretation of this fact depends on frame where we work. Considering directly f ( R ) gravity, one can say that increasing of mass occurs by the “gravitational sphere” outside the star with some “effective mass”. On the other hand, in conformal scalar-tensor theory, we also have a dilaton sphere (or “disphere”) outside the star but its contribution to gravitational mass for distant observer is negligible. We show that it is possible to discriminate modified theories of gravity from General Relativity due to the gravitational redshift of the thermal spectrum emerging from the surface of the star. | 161,969 |
title: Neutron-induced fission cross section of Np 237 in the keV to MeV range at the CERN n_TOF facility; abstract: We experimentally determined the neutron-induced fission cross section of Np-237 at the high-resolution and high-intensity facility n_TOF, at CERN, in the energy range 100 keV to 9 MeV, using the U-235(n, f) and U-238(n, f) cross section standards below and above 2 MeV, respectively. Moreover, a fast ionization chamber was used in order to detect the fission fragments from the reactions and the targets were characterized as far as their mass and homogeneity are concerned by means of a spectroscopy and Rutherford backscattering spectroscopy respectively. Finally, theoretical calculations within the Hauser-Feshbach formalism have been performed, employing the EMPIRE code, and the model parameters were tuned in order to successfully reproduce the experimental fission cross-sectional data and simultaneously all the competing reaction channels. | 161,970 |
title: When do stars in 47 Tucanae lose their mass; abstract: By examining the diffusion of young white dwarfs through the core of the globular cluster 47 Tucanae, we estimate the time when the progenitor star lost the bulk of its mass to become a white dwarf. According to stellar evolution models of the white-dwarf progenitors in 47 Tucanae, we find this epoch to coincide approximately with the star ascending the asymptotic giant branch ($3.0 \\pm 8.1$ Myr before the tip of the AGB) and more than ninety million years after the helium flash (with ninety-percent confidence). From the diffusion of the young white dwarfs we can exclude the hypothesis that the bulk of the mass loss occurs on the red-giant branch at the four-sigma level. Furthermore, we find that the radial distribution of horizontal branch stars is consistent with that of the red-giant stars and upper-main-sequence stars and inconsistent with the loss of more than 0.2 solar masses on the red-giant branch at the six-sigma level. | 161,971 |
title: WIND BRAKING OF MAGNETARS; abstract: We explore the wind braking of magnetars considering recent observations challenging the traditional magnetar model. There is evidence for strong multipole magnetic fields in active magnetars, but the dipole field inferred from spin-down measurements may be strongly biased by particle wind. Recent observations challenging the traditional model of magnetars may be explained naturally by the wind braking scenario: (1) the supernova energies of magnetars are of normal value; (2) the non-detection in Fermi observations of magnetars; (3) the problem posed by low magnetic field soft gamma-ray repeaters; (4) the relation between magnetars and high magnetic field pulsars; and (5) a decreasing period derivative during magnetar outbursts. Transient magnetars with L-x\u003c-(E) over dot(rot) may still be magnetic dipole braking. This may explain why low luminosity magnetars are more likely to have radio emissions. A strong reduction of the dipole magnetic field is possible only when the particle wind is very collimated at the star surface. A small reduction of the dipole magnetic field may result from detailed considerations of magnetar wind luminosity. In the wind braking scenario, magnetars are neutron stars with a strong multipole field. For some sources, a strong dipole field may no longer be needed. A magnetism-powered pulsar wind nebula will be one of the consequences of wind braking. For a magnetism-powered pulsar wind nebula, we should see a correlation between the nebula luminosity and the magnetar luminosity. Under the wind braking scenario, a braking index smaller than three is expected. Future braking index measurement of a magnetar may tell us whether magnetars are wind braking or magnetic dipole braking. | 161,972 |
title: Oscillator Models of the Solar Cycle: Towards the Development of Inversion Methods; abstract: This article reviews some of the leading results obtained in solar dynamo physics by using temporal oscillator models as a tool to interpret observational data and dynamo model predictions. We discuss how solar observational data such as the sunspot number is used to infer the leading quantities responsible for the solar variability during the last few centuries. Moreover, we discuss the advantages and difficulties of using inversion methods (or backward methods) over forward methods to interpret the solar dynamo data. We argue that this approach could help us to have a better insight about the leading physical processes responsible for solar dynamo, in a similar manner as helioseismology has helped to achieve a better insight on the thermodynamic structure and flow dynamics in the Sun’s interior. | 161,973 |
title: Tuning Crystal Field Potential by Orbital Dilution in $d^4$ Oxides; abstract: We investigate the interplay between Coulomb driven orbital order and octahedral distortions in strongly correlated Mott insulators due to orbital dilution, i.e., doping by metal ions without an orbital degree of freedom. In particular, we focus on layered transition metal oxides and study the effective spin-orbital exchange due to $d^3$ substitution at $d^4$ sites. The structure of the $d^3-d^4$ spin-orbital coupling between the impurity and the host in the presence of octahedral rotations favors a distinct type of orbital polarization pointing towards the impurity and outside the impurity--host plane. This yields an effective lattice potential that generally competes with that associated with flat octahedra and, in turn, can drive an inversion of the crystal field interaction. | 161,974 |
title: Improved search for elementary particles with fractional electric charge.; abstract: The SLAC Quark Search Group has demonstrated successful operation of a low cost, high mass throughput Millikan apparatus designed to search for fractionally charged particles. About six million silicone oil drops were measured with no evidence of fractional charges. A second experiment is under construction with 100 times greater throughput which will utilize optimized search fluids. | 161,975 |
title: Thermal modification of bottomonium spectra from QCD sum rules with the maximum entropy method; abstract: Abstract The bottomonium spectral functions at finite temperature are analyzed by employing QCD sum rules with the maximum entropy method. This approach enables us to extract the spectral functions without any phenomenological parametrization, and thus to visualize deformation of the spectral functions due to temperature effects estimated from quenched lattice QCD data. As a result, it is found that ϒ and η b survive in hot matter of temperature up to at least 2.3 T c and 2.1 T c , respectively, while χ b 0 and χ b 1 will disappear at T 2.5 T c . Furthermore, a detailed analysis of the vector channel shows that the spectral function in the region of the lowest peak at T = 0 contains contributions from the excited states, ϒ ( 2 S ) and ϒ ( 3 S ) , as well as the ground states ϒ ( 1 S ) . Our results at finite T are consistent with the picture that the excited states of bottomonia dissociate at lower temperature than that of the ground state. Assuming this picture, we find that ϒ ( 2 S ) and ϒ ( 3 S ) disappear at T = 1.5 – 2.0 T c . | 161,976 |
title: Order parameters for the confinement-deconfinement phase transition in SU(N) gauge theories with quarks; abstract: Abstract In the confined phase of an SU( N ) gauge theory finite energy bound clusters of n q quarks and n q antiquarks occur only if the N -ality ( n q − n q ) mod N =0. In the deconfined phase there is no such restriction. We argue that this feature permits the construction of order parameters in the microcanomical ensemble that vanish in the confined phase and become finite in the deconfined phase. | 161,977 |
title: Domain-Wall Standard Model in non-compact 5D and LHC phenomenology.; abstract: We propose a framework to construct \"Domain-Wall Standard Model\" in a non compact 5-dimensional space-time, where all the Standard Model (SM) fields are localized in certain domains of the 5th dimension and the SM is realized as a 4-dimensional effective theory without any compactification for the 5th dimension. In this context, we investigate the collider phenomenology of the Kaluza-Klein (KK) modes of the SM gauge bosons and the current constraints from the search for a new gauge boson resonance at the LHC Run-2. The couplings of the SM fermions with the KK-mode gauge bosons depend on the configuration of the SM fermions in the 5-dimensional bulk. This \"geometry\" of the model can be tested at the future Large Hadron Collider experiment, once a KK-mode of the SM gauge boson is discovered. | 161,978 |
title: Quantum Measurement and Feedback with Atomic Hyperfine Spins; abstract: I will review our ongoing research on continuous non-demolition measurement of collective hyperfine spin in a dilute cloud of laser-cooled Cesium atoms. Connections with quantum filtering, parameter estimation and quantum information theory will be highlighted. | 161,979 |
title: First Evidence for a Charm Radial Excitation, D*'; abstract: Using D∗+ mesons exclusively reconstructed in the DELPHI detector at LEP, an excess of 66±14(stat.) events is observed in the D∗+π+π− final state with a mass of 2637±2(stat.)±6(syst.) MeV/c2 and a full width smaller than 15 MeV/c2 (95% C.L.). This signal is compatible with the expected decay of a radially excited D∗′ (JP=1−) meson. | 161,980 |
title: One-domain approach for heat transfer between a porous medium and a fluid; abstract: The purpose of this work is to investigate the extents of the local thermal equilibrium (LTE) assumption at the fluid-porous medium boundary (i.e., in a heterogeneous region). The analysis is performed in terms of the one-domain approach. Therefore, we posed and solved the associated closure problems in order to compute the spatial dependence of the effective coefficients at the fluid-porous medium boundary. Steady-state comparisons with direct numerical simulations evidence that the LTE is, in general, justifiable everywhere in the system, i.e., in both homogeneous and heterogeneous regions. | 161,981 |
title: Relativistic spectral features from X-ray-illuminated spots and the measure of the black hole mass in active galactic nuclei; abstract: Narrow spectral features in the 5-6 keV range were recently discovered in the X-ray spectra of a few active galactic nuclei. We discuss the possibility that these features are due to localized spots which occur on the surface of an accretion disc following its illumination by flares. We present detailed line profiles as a function of orbital phase of the spot and its radial distance from a central black hole. Comparison of these computed profiles with observed features can help to estimate parameters of the system. In principle, this method can provide a powerful tool to measure the mass of super-massive black holes in active galactic nuclei. By comparing our simulations with the Chandra and XMM-Newton results, we show, however, that spectra from present generation X-ray satellites are not of good enough quality to exploit the method fully and determine the black hole mass with sufficient accuracy. This task has to be deferred to future missions with high throughput and high energy resolution, such as Constellation-X and Xeus. | 161,982 |
title: Production of baryon resonances in collisions of 4He nuclei with carbon nuclei at a momentum of 4.2 GeV/c per nucleon; abstract: Under conditions of 4π geometry, Δ0-and Δ++-resonance production in collisions of 4He nuclei with carbon nuclei at a momentum of 4.2 GeV/c per nucleon was investigated for the first time. The resonance masses and widths are estimated by analyzing the experimental and background invariant-mass distributions of (pπ ±) pairs. Contributions to pion production from Δ-resonance decays, as well as from direct pion production, are determined. The results are compared with corresponding data obtained for CC collisions at the same primary momentum of 4.2 GeV/c per nucleon. By and large, the results obtained here comply with the existence of a collective mechanism of delta-isobar excitation in nuclei. | 161,983 |
title: Research frontiers in magnetic materials at soft X-ray synchrotron radiation facilities; abstract: Current and anticipated future research frontiers in magnetism and magnetic materials are discussed from a perspective of soft X-ray synchrotron utilization. Topics covered include dimensionality (including e!ects of spatial dimensions and di!ering time scales), magneto-electronics, structure/property relationships, and exploratory materials, with an emphasis on challenges that limit the understanding and advancement of these areas. Many soft X-ray spectroscopies can be used to study magnetism associated with transition and rare earth metals with element- and chemical-state speci\"city and large cross-sections associated with dipole transitions from pPd and dPf states. Established electron spectroscopies, including spin-resolved techniques, yield near-surface sensitivity in conjunction with linear and circular magnetic dichroism. Emerging photon-based scattering and Faraday and Kerr magneto-optical measurements can be used beyond the near-surface region and in applied magnetic \"elds. Microscopies based on either electron or photon spectroscopies to image the magnetization at 50 nm resolution are also emerging, as are time-resolved measurements that utilize the natural time structure of synchrotron sources. Examples of research using these techniques to impact our fundamental understanding of magnetism and magnetic materials are given, as are future opportunities. ( 1999 Elsevier Science B.V. All rights reserved. | 161,984 |
title: Measurement of magnetic field gradients using Raman spectroscopy in a fountain; abstract: In many experiments involving cold atoms, it is crucial to know the strength of the magnetic field and/or the magnetic field gradient at the precise location of a measurement. While auxiliary sensors can provide some of this information, the sensors are usually not perfectly co-located with the atoms and so can only provide an approximation to the magnetic field strength. In this article, we describe a technique to measure the magnetic field, based on Raman spectroscopy, using the same atomic fountain source that will be used in future magnetically sensitive measurements. | 161,985 |
title: Fabrication and Characterization of Cu2ZnSnS4 Powders by a Hydrothermal Method; abstract: In this study, Cu2ZnSnS4 (CZTS) powders are successfully synthesized by a simple hydrothermal method, and the concentration of thiourea, reaction time, reaction temperature, and precursor concentration ratio (Zn/Sn) are all examined in order to obtain the optimal conditions for this process. In addition, the characteristics of the resulting powder are examined using the X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Raman, transmission electron microscope (TEM) and ultraviolet–visible (UV–vis) techniques. The results indicate that the concentration of sulfur ions is 6 times of that of the copper ions, and that the production process required a reaction time of 72 h and a reaction temperature of 180 °C, and the energy gap of the CZTS powder is approximately 1.45 eV. | 161,986 |
title: A model for the Z-track phenomenon in GX 5-1 and observational evidence for the physical origins of the kHz QPO; abstract: We present the results of a combined investigation of the spectral and kHz QPO evolution around the Z-track in GX 5-1 based on high-quality Rossi-XTE data. In spectral analysis, we find that the Extended ADC emission model provides very good fits to all of the spectra, and the results point clearly to a model for the nature of the Z-track in this source, in agreement with previous results for the similar source GX 340+0. In this model, at the soft apex of the Z-track, the mass accretion rate u M is at its minimum and the neutron star has its lowest temperature; but as the source moves along the normal branch, the luminosity of the Comptonized emission increases, indicating that u M increases and the neutron star gets hotter. The measured flux f of the neutron star emission increases by a factor of ten becoming super-Eddington, and we propose that this causes disruption of the inner disk and the formation of jets. In flaring, the luminosity of the dominant Comptonized emission from the accretion disk corona is constant, while the neutron star emission increases, and we propose for the first time that flaring consists of unstable nuclear burning on the neutron star, supported by the agreement between the measured mass accretion rate per unit area u m at the onset of flaring and the theoretical critical value at which burning becomes unstable. There is a striking correlation between the frequencies of the kHz QPO and the ratio of the flux to the Eddington value: f /fEdd, suggesting an explanation of the higher frequency QPO and of its variation along the Z-track. It is well known that a Keplerian orbit in the disk at this frequency corresponds to a position some distance from the neutron star; we propose that the oscillation always occurs at the inner disk edge, which moves radially outwards on the upper normal and horizontal branches as the measured increasing radiation pressure increasingly disrupts the inner disk. | 161,987 |
title: Midwave infrared InAs/GaSb superlattice photodiode with a dopant-free p–n junction; abstract: Midwave infrared (MWIR) InAs/GaSb superlattice (SL) photodiode with a dopant-free p–n junction was fabricated by molecular beam epitaxy on GaSb substrate. Depending on the thickness ratio between InAs and GaSb layers in the SL period, the residual background carriers of this adjustable material can be either n-type or p-type. Using this flexibility in residual doping of the SL material, the p–n junction of the device is made with different non-intentionally doped (nid) SL structures. The SL photodiode processed shows a cut-off wavelength at 4.65 μm at 77 K, residual carrier concentration equal to 1.75 × 1015 cm−3, dark current density as low as 2.8 × 10−8 A/cm2 at 50 mV reverse bias and R0A product as high as 2 × 106 Ω cm2. The results obtained demonstrate the possibility to fabricate a SL pin photodiode without intentional doping the pn junction. | 161,988 |
title: Experimental study of two-proton correlated emission from S-29 excited states; abstract: An experiment of a {sup 29}S beam bombarding a {sup 197}Au target at an energy of 49.2 MeV/u has been performed to study the two-proton correlated emission from {sup 29}S excited states. Complete-kinematics measurements were carried out in the experiment. The relative momentum, opening angle, and relative energy of two protons, as well as the invariant mass of the final system, were deduced by relativistic-kinematics reconstruction. The {sup 27}Si-p-p coincident events were picked out under strict conditions and the phenomenon of p-p correlations was observed among these events. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like {sup 2}He cluster emission, three-body phase-space decay, and two-body sequential emission were taken into account. Associated with the Monte Carlo simulations, the present results show that two protons emitted from the excited states between 9.6 MeV and 10.4 MeV exhibit the features of {sup 2}He cluster decay with a branching ratio of 29{sub -11}{sup +10}%. | 161,989 |
title: Nuclear ground-state properties and self-consistent calculations with the skyrme interaction: (I). Spherical description; abstract: Abstract The parameters of the effective Skyrme interaction are determined by requiring that they accurately reproduce the total binding energies and charge radii of magic nuclei in spherical self-consistent calculations. It is shown that many parameter sets can satisfy these requirements. They differ essentially by the single-particle spectra they give. A detailed study of the influence of the force parameters on the binding energies, charge densities, radii and single-particle energies of magic nuclei is made. Extensive self-consistent calculations covering over two hundred nuclei have been performed in a spherical scheme using one of the parameter sets. The effects of pairing correlations are discussed. The magnitude of the corrections due to the deformation in the rare earth region is indicated. The good overall agreement of the results with experimental data shows that the Skyrme parametrisation of the effective interaction is adequate. The remaining discrepancies may be attributed essentially to dynamic collective effects not included in the present approach. | 161,990 |
title: Lower bounds on charged Higgs bosons from LEP and the Tevatron; abstract: Abstract We point out that charged Higgs bosons can decay into final states different from τ+ντ and c s , even when they are light enough to be produced at LEP II or at the Tevatron through top quark decays. These additional decay modes are overlooked in ongoing searches even though they alter the existing lower bounds on the mass of the charged Higgs bosons that are present in supersymmetric and two Higgs doublets models. | 161,991 |
title: Measurement of an excess of B̄→D(*) τ-ν̄τ decays and implications for charged Higgs bosons; abstract: Based on the full BABAR data sample, we report improved measurements of the ratios R(D)=B(B→Dτ-ντ)/ B(B→Dl-νl) and R(D*)=B(B→D*τ-ντ)/ B(B→D*l-νl), where l refers to either an electron or muon. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D)=0.440±0.058±0.042 and R(D*)=0.332±0. 024±0.018, which exceed the standard model expectations by 2.0σ and 2.7σ, respectively. Taken together, the results disagree with these expectations at the 3.4σ level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results. © 2013 American Physical Society. | 161,992 |
title: Improved two-wavelength demultiplexing InGaAsP photodetector; abstract: The structure of the previously reported InGaAsP two-wavelength demultiplexing photodetector has been inverted to circumvent fabrication problems associated with dissolution of the lower-bandgap quaternary layer during the LPE growth of subsequent higher bandgap layers. In addition, lower doping levels have been achieved in the LPE layers. The result of these modifications has been devices with greatly improved optical and electrical characteristics. The long-wavelength cutoff has been extended to 1.6 μm. | 161,993 |
title: Electroweak standard model: Tests at LEP; abstract: Abstract Since the coming into operation of LEP at CERN, in 1989, the Electroweak Standard Model has been tested with an unprecedented precision, both concerning the number of independent physics quantities which have been measured and the accuracy of the measurements. In this report, the most significant experimental results and their implications for the Electroweak Standard Model are reviewed. | 161,994 |
title: A Field Cancellation Signal Extraction Method for Magnetic Particle Imaging; abstract: Nowadays, magnetic particle imaging (MPI) signal detection and excitation happens at the same time. This concept, however, leads to a strong coupling of the drive (excitation) field (DF) with the receive chain. As the induced DF signal is several orders of magnitude higher, special measures have to be taken to suppress this signal portion within the receive signal to keep the required dynamic range of the subsequent analog-to-digital conversion in a technically feasible range. For frequency space MPI, high-order bandstop-filters have been successfully used to remove the DF signals, which unfortunately removes the fundamental harmonic components of the signal of the magnetic nanoparticles (MNP) as well. According to the Langevin theory, the fundamental harmonic component has a large signal contribution and is important for direct reconstruction of the particle concentration. To separate the fundamental harmonic component of the MNP from the induced DF signal, different concepts have been proposed using signal cancellation based on additional DF signals, also in combination with additional filtering. In this paper, we propose a field cancellation (FC) concept in which a receive coil (RC) consists of a series connection of a primary coil in combination with an additional cancellation coil. The geometry of the primary coil was chosen to be sensitive for the MNP signal while the cancellation coil was chosen to minimize the overall inductive coupling of the FC-RC with the DF. Sensitivity plots and mutual coupling coefficients were calculated using a thin-wire approximation. A prototype FC-RC was manufactured and the effectiveness of the reduction of the mutual inductive coupling ( ${d}$ ) was tested in an existing mouse MPI scanner. The difference between the simulations ( $d_{s}=70$ dB) and the measurements ( $d_{\\rm m}= 55$ dB) indicated the feasibility as well as the need for further investigations. | 161,995 |
title: Binary droplet collision simulations by a multiphase cascaded lattice Boltzmann method; abstract: Three-dimensional binary droplet collisions are studied using a multiphase cascaded lattice Boltzmann method (LBM). With this model it is possible to simulate collisions with a Weber number of up to 100 and a Reynolds number of up to 1000, at a liquid to gas density ratio of over 100. This is made possible by improvements to the collision operator of the LBM. The cascaded LBM in three dimensions is introduced, in which additional relaxation rates for higher order moments, defined in a co-moving reference frame, are incorporated into the collision operator. It is shown that these relaxation rates can be tuned to reduce spurious velocities around curved phase boundaries, without compromising the accuracy of the simulation results. The range of attainable Reynolds numbers is therefore increased. Different outcomes from both head-on and off-centre collisions are simulated, for both equal and unequal size droplets, including coalescence, head-on separation, and off-centre separation. For head-on collisions the critical Weber number between coalescence and separation is shown to decrease with decreasing ambient gas pressure. The variation of critical Weber number with droplet size ratio is also studied. Comparisons are made with the theoretical predictions of Tang et al. [“Bouncing, coalescence, and separation in head-on collision of unequal-size droplets,” Phys. Fluids24, 022101 and the effect of ambient gas pressure is again considered. For off-centre collisions, boundaries between different collision outcomes are accurately defined and quantitative comparisons are made with the theoretical predictions of Rabe et al. [“Experimental investigation of water droplet binary collisions and description of outcomes with a symmetric Weber number,” Phys. Fluids22, 047101 (2010)]. While general agreement between the simulated and theoretical boundaries is presented, deviations due to varying liquid viscosity are observed. Finally, the prediction of the independence of regime boundaries with varying droplet size ratio, when using the symmetric Weber number as defined by Rabe et al., is discussed. Simulation results showing qualitative agreement are presented, although some discrepancies are reported. | 161,996 |
title: Tensor forces and spin susceptibility of a Fermi liquid; abstract: Abstract We derive a formula for the spin magnetic susceptibility of a Fermi liquid with tensor quasiparticle interaction. Using theoretically calculated values of the Fermi liquid parameters we study the effect of the tensor quasiparticle interaction on the magnetic susceptibility of neutron matter and on the spin and spin-isospin symmetry energies of nuclear matter. | 161,997 |
title: An investigation of Bose-Einstein correlations in muon-nucleon interactions at 490 GeV; abstract: Abstract An investigation of Bose-Einstein correlations amongst like-charged pions produced in muon-nucleon interactions at 490 GeV is presented. On top of a broader enhancement, a steep increase in the correlations at small four-momentum differences between the two pions is observed which may be explained by the contribution from decays of resonances (ϱ-mesons). A two-dimensional analysis discriminates between two different parametrizations of the Bose-Einstein effect, strongly favoring the Lorentz-invariant parametrization over a parametrization based on a Gaussian source distribution in space and time. | 161,998 |
title: On field theory for massive and massless spin52 particles; abstract: Abstract Wave equations and actions are derived for free, massive and massless, spin - 5 2 fields, which lead to ghost-free propagators with the correct number of propagating states. The massive theory is constructed from the root method, whereas the massless theory is derived from a direct analysis of the propagator. A discontinuity exists in the description of massive and massless spin - 5 2 fields in the sense that the zero-mass limit of the massive theory does not lead to the massless theory, but contains too many propagating modes. | 161,999 |
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