text
stringlengths 6
128k
|
|---|
The present work is devoted to develop a computational model using the Gate
Monte Carlo software for the simulation of a 6MV photon beam given by Elekta
Synergy Platform medical linear accelerator treatment head. The model includes
the major components of the multileaf accelerator head and a homogeneous water
phantom. Calculations were performed for a photon beam with several treatment
fields size ranging from 5*5 cm2 to 30*30 cm2 at 100 cm distance from source.
The simulation is successfully validated by comparison with experimental
distributions measured at the Regional Hassan II Oncology Center. Good
agreement between simulations and measurements was observed, with dose
differences of about 1.6% and 1.8% for depth doses and lateral dose profiles,
respectively. The gamma index comparisons were also performed where more than
98% of the points for all simulations passed the standard quality assurance
criteria of 3mm/3%.
|
Persistent homology provides a new approach for the topological
simplification of big data via measuring the life time of intrinsic topological
features in a filtration process and has found its success in scientific and
engineering applications. However, such a success is essentially limited to
qualitative data characterization, identification and analysis (CIA). In this
work, we outline a general protocol to construct objective-oriented persistent
homology methods. The minimization of the objective functional leads to a
Laplace-Beltrami operator which generates a multiscale representation of the
initial data and offers an objective oriented filtration process. The resulting
differential geometry based objective-oriented persistent homology is able to
preserve desirable geometric features in the evolutionary filtration and
enhances the corresponding topological persistence. The consistence between
Laplace-Beltrami flow based filtration and Euclidean distance based filtration
is confirmed on the Vietoris-Rips complex for a large amount of numerical
tests. The convergence and reliability of the present Laplace-Beltrami flow
based cubical complex filtration approach are analyzed over various spatial and
temporal mesh sizes. The efficiency and robustness of the present method are
verified by more than 500 fullerene molecules. It is shown that the proposed
persistent homology based quantitative model offers good predictions of total
curvature energies for ten types of fullerene isomers. The present work offers
the first example to design objective-oriented persistent homology to enhance
or preserve desirable features in the original data during the filtration
process and then automatically detect or extract the corresponding topological
traits from the data.
|
We systematically analyze the radiative corrections to the $S_3$ symmetric
neutrino mass matrix at high energy scale, say the GUT scale, in the charged
lepton basis. There are significant corrections to the neutrino parameters both
in the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM)
with large tan$\beta$, when the renormalization group evolution (RGE) and
seesaw threshold effects are taken into consideration. We find that in the SM
all three mixing angles and atmospheric mass squared difference are
simultaneously obtained in their current 3$\sigma$ ranges at the electroweak
scale. However, the solar mass squared difference is found to be larger than
its allowed 3$\sigma$ range at the low scale in this case. There are
significant contributions to neutrino masses and mixing angles in the MSSM with
large tan$\beta$ from the RGEs even in the absence of seesaw threshold
corrections. However, we find that the mass squared differences and the mixing
angles are obtained in their current 3$\sigma$ ranges at low energy when the
seesaw threshold effects are also taken into account in the MSSM with large
tan$\beta$.
|
Runtime monitoring is generally considered a light-weight alternative to
formal verification. In safety-critical systems, however, the monitor itself is
a critical component. For example, if the monitor is responsible for initiating
emergency protocols, as proposed in a recent aviation standard, then the safety
of the entire system critically depends on guarantees of the correctness of the
monitor. In this paper, we present a verification extension to the Lola
monitoring language that integrates the efficient specification of the monitor
with Hoare-style annotations that guarantee the correctness of the monitor
specification. We add two new operators, assume and assert, which specify
assumptions of the monitor and expectations on its output, respectively. The
validity of the annotations is established by an integrated SMT solver. We
report on experience in applying the approach to specifications from the
avionics domain, where the annotation with assumptions and assertions has lead
to the discovery of safety-critical errors in the specifications. The errors
range from incorrect default values in offset computations to complex
algorithmic errors that result in unexpected temporal patterns.
|
By generalizing Bo Gao's approach [Phys. Rev. A 58, 1728 (1998)] for solving
the Schr\"{o}dinger equation for an isotropic van der Waals (vdW) potential to
the systems with a multi-scale anisotropic long-range interaction, we derive
the solutions for the Schr\"{o}dinger equation for an anisotropic dipole-dipole
interaction plus an isotropic attractive vdW potential, i.e.,
${C_d(1-3\cos^2\theta)}/{r^3}-{C_6}/{r^6}$, which is projected to the subspace
with angular momentum $l\leq l_{\rm cut}$, with $l_{\rm cut}$ being an
arbitrary angular-momentum cutoff. Here $\theta$ is the polar angle of the
coordinate $\boldsymbol{r}$ and $r=|\boldsymbol{r}|$. The asymptotic behaviors
of these solutions for $r\rightarrow 0$ and $r\rightarrow \infty$ are obtained.
These results can be used in the research of collisions and chemical reactions
between ultra-cold polar molecules in a static electric field. Our approach to
derive the solutions can be applied to the systems with a general long-range
potential $\sum_{\lambda= 2}^{\lambda_{\rm max}}
{V_\lambda(\theta,\varphi)}/{r^\lambda}$, with $\varphi$ being the azimuthal
angle of $\boldsymbol{r}$, and thus can be used in various problems on
molecule-molecule interaction.
|
We study the influence of nonlocality in the interaction on two spin one
pairing patterns of two-flavor quark matter: the anisotropic blue color paring
besides the usual two color superconducting matter (2SCb), in which red and
green colors are paired, and the color spin locking phase (CSL). The effect of
nonlocality on the gaps is rather large and the pairings exhibit a strong
dependence on the form factor of the interaction, especially in the low density
region. The application of these small spin-one condensates for compact stars
is analyzed: the early onset of quark matter in the nonlocal models may help to
stabilize hybrid star configurations. While the anisotropic blue quark pairing
does not survive a big asymmetry in flavor space as imposed by the charge
neutrality condition, the CSL phase as a flavor independent pairing can be
realized as neutral matter in compact star cores. However, smooth form factors
and the missmatch between the flavor chemical potential in neutral matter make
the effective gaps of the order of magnitude $\simeq 10$ keV, and a more
systematic analysis is needed to decide whether such small gaps could be
consistent with the cooling phenomenology.
|
We present a summary of an asteroseismic signature of helium ionization
reported by Houdek & Gough (2007, 2008, 2009) for low-degree p modes in
solar-type stars, and illustrate its applications for asteroseismic diagnoses.
|
In this paper we first investigate for what positive integers $a,b,c$ every
nonnegative integer $n$ can be represented as $x(ax+1)+y(by+1)+z(cz+1)$ with
$x,y,z$ integers. We show that $(a,b,c)$ can be either of the following seven
triples: $$(1,2,3),\ (1,2,4),\ (1,2,5),\ (2,2,4),\ (2,2,5),\ (2,3,3),\
(2,3,4),$$ and conjecture that any triple $(a,b,c)$ among $$(2,2,6),\ (2,3,5),\
(2,3,7),\ (2,3,8),\ (2,3,9),\ (2,3,10)$$ also has the desired property. For
integers $0\le b\le c\le d\le a$ with $a>2$, we prove that any nonnegative
integer can be represented as $x(ax+b)+y(ay+c)+z(az+d)$ with $x,y,z$ integers,
if and only if the quadruple $(a,b,c,d)$ is among $$(3,0,1,2),\ (3,1,1,2),\
(3,1,2,2),\ (3,1,2,3),\ (4,1,2,3).$$
|
While deep learning methods have shown great success in medical image
analysis, they require a number of medical images to train. Due to data privacy
concerns and unavailability of medical annotators, it is oftentimes very
difficult to obtain a lot of labeled medical images for model training. In this
paper, we study cross-modality data augmentation to mitigate the data
deficiency issue in the medical imaging domain. We propose a discriminative
unpaired image-to-image translation model which translates images in source
modality into images in target modality where the translation task is conducted
jointly with the downstream prediction task and the translation is guided by
the prediction. Experiments on two applications demonstrate the effectiveness
of our method.
|
Starting from an effective action for quantum gravity, we calculate the
quantum gravitational corrections to the Wald entropy of a four dimensional
non-extremal Reissner-Nordstr\"om (RN) black hole in the limit of small
electric charge, generalising a previous calculation carried out by Calmet and
Kuipers [1] for a Schwarzschild black hole. We show that, at second order in
the Ricci curvature, the RN metric receives quantum corrections which shift the
classical position of the event horizon. We apply the Wald entropy formula by
integrating over the perimeter of the quantum corrected event horizon. We then
compute the quantum gravitational corrections to the temperature and the
pressure of the black hole.
|
Sound event detection (SED) has gained increasing attention with its wide
application in surveillance, video indexing, etc. Existing models in SED mainly
generate frame-level prediction, converting it into a sequence multi-label
classification problem. A critical issue with the frame-based model is that it
pursues the best frame-level prediction rather than the best event-level
prediction. Besides, it needs post-processing and cannot be trained in an
end-to-end way. This paper firstly presents the one-dimensional Detection
Transformer (1D-DETR), inspired by Detection Transformer for image object
detection. Furthermore, given the characteristics of SED, the audio query
branch and a one-to-many matching strategy for fine-tuning the model are added
to 1D-DETR to form Sound Event Detection Transformer (SEDT). To our knowledge,
SEDT is the first event-based and end-to-end SED model. Experiments are
conducted on the URBAN-SED dataset and the DCASE2019 Task4 dataset, and both
show that SEDT can achieve competitive performance.
|
Let X be a Hermitian locally symmetric space. We prove that every Chern class
of X has a canonical lift to the cohomology of the Baily- Borel-Satake
compactification X* of X and that the resulting Chern numbers satisfy the
Hirzebruch proportionality formula with respect to the compact dual X^ of X.
The same result holds for any automorphic vector bundle over X in place of the
tangent bundle. As a consequence there is a surjection of the subalgebra of
H*(X*) generated by these lifted classes onto H*(X^). The method of proof is to
construct fiberwise flat connections on these bundles near the singular strata
of X*, where one then finds de Rham representatives of the Chern classes which
are pulled back from the strata.
|
The purpose of this note is to offer some partition implications of a
$q$-series that is connected to the second Atkin-Garvan moment. Inequalities
and relationships among the number of divisors and partitions are provided as
consequences.
|
The physical analysis of condensed matter systems can be difficult due to
strong coupling, but the mathematical context of the AdS/CFT correspondence
enables non-perturbative descriptions in terms of dual weakly coupled systems.
This brief review explores the holographic condensed matter applications of
AdS/CFT, particularly through the lens of a high-$T_c$ superconductor outside a
Schwarzchild black hole in Anti-de Sitter space. A simple two-dimensional
electron condensate Lagrangian is examined first, as employed by G. T.
Horowitz, later used to calculate a frequency-dependent conductivity and a free
energy analysis; the asymptotics of both in this procedure, as examined by P.
S\"aterskog, are also reviewed. An extended Lagrangian with a higher order
Maxwell term is assessed thereafter, with a conductivity peak obtained at low
frequencies described well by the Drude model in certain limits. The behavior
of Drude model parameters in these limits is also investigated.
|
LSH (locality sensitive hashing) had emerged as a powerful technique in
nearest-neighbor search in high dimensions [IM98, HIM12]. Given a point set $P$
in a metric space, and given parameters $r$ and $\varepsilon > 0$, the task is
to preprocess the point set, such that given a query point $q$, one can quickly
decide if $q$ is in distance at most $\leq r$ or $\geq (1+\varepsilon)r$ from
the point set $P$. Once such a near-neighbor data-structure is available, one
can reduce the general nearest-neighbor search to logarithmic number of queries
in such structures [IM98, Har01, HIM12].
In this note, we revisit the most basic settings, where $P$ is a set of
points in the binary hypercube $\{0,1\}^d$, under the $L_1$/Hamming metric, and
present a short description of the LSH scheme in this case. We emphasize that
there is no new contribution in this note, except (maybe) the presentation
itself, which is inspired by the authors recent work [HM17].
|
Recombination of H3+ with electrons was studied in a low temperature plasma
in helium. The plasma recombination rate is driven by two body, H3+ + e, and
three-body, H3+ + e + He, processes with the rate coefficients 7.5x10^{-8}cm3/s
and 2.8x10^{-25}cm6/s correspondingly at 260K. The two-body rate coefficient is
in excellent agreement with results from storage ring experiments and
theoretical calculations. We suggest that the three-body recombination involves
formation of highly excited Rydberg neutral H3 followed by an l- or m- changing
collision with He. Plasma electron spectroscopy indicates the presence of H3.
|
Inverted-gap GaSb/InAs quantum wells have long been predicted to show quantum
spin Hall insulator (QSHI) behavior. The experimental characterization of the
QSHI phase in these systems has relied on the presence of quantized edge
transport near charge neutrality. However, experimental data showing the
presence of edge conductance in the \emph{trivial} regime suggest that
additional experimental signatures are needed to characterize the QSHI phase.
Here we show that electric field- induced gap oscillations can be used as an
indicator of the presence of helical edge states in system. By studying a
realistic low-energy model GaSb/InAs quantum wells derived from $k \cdot p$
band theory, we show that such oscillations are bound to appear in narrow
samples as the system is driven to the the the topological phase by the
electric field. Our results can serve as a guide for the search of additional
experimental signatures of the presence of topologically-protected helical edge
states in GaSb/InAs systems.
|
The resonator-induced phase gate is a multi-qubit controlled-phase gate for
fixed-frequency superconducting qubits. Through off-resonant driving of a bus
resonator, statically coupled qubits acquire a state-dependent phase. However,
photon loss leads to dephasing during the gate, and any residual entanglement
between the resonator and qubits after the gate leads to decoherence. Here we
consider how to shape the drive pulse to minimize these unwanted effects.
First, we review how the gate's entangling and dephasing rates depend on the
system parameters and validate closed-form solutions against direct numerical
solution of a master equation. Next, we propose spline pulse shapes that reduce
residual qubit-bus entanglement, are robust to imprecise knowledge of the
resonator shift, and can be shortened by using higher-degree polynomials.
Finally, we present a procedure that optimizes over the subspace of pulses that
leave the resonator unpopulated. This finds shaped drive pulses that further
reduce the gate duration. Assuming realistic parameters, we exhibit shaped
pulses that have the potential to realize ~212 ns spline pulse gates and ~120
ns optimized gates with ~6e-4 average gate infidelity. These examples do not
represent fundamental limits of the gate and in principle even shorter gates
may be achievable.
|
In this paper first we survey the Tur\'an type inequalities and related
problems for the Bessel functions of the first kind. Then we extend the known
higher order Tur\'an type inequalities for Bessel functions of the first kind
to real parameters and we deduce new closed integral representation formulae
for the second kind Neumann type series of Bessel functions of the first kind
occurring in the study of Tur\'an determinants of Bessel functions of the first
kind. At the end of the paper we prove a Tur\'an type inequality for the Bessel
functions of the second kind.
|
We consider the electronic transport in bounded semiconductors in the
presence of an external magnetic field. Taking into account appropriate
boundary conditions for the current density at the contacts, a change in the
magnetoresistance of bulk semiconductors is found as compared with the usual
theory of galvanomagnetic effects in boundless media. New mechanism in
magnetoresistance connected with the boundary conditions arises. In particular,
even when the relaxation time is independent of the electron energy,
magnetoresistance is not vanish.
|
This paper introduces EvoCraft, a framework for Minecraft designed to study
open-ended algorithms. We introduce an API that provides an open-source Python
interface for communicating with Minecraft to place and track blocks. In
contrast to previous work in Minecraft that focused on learning to play the
game, the grand challenge we pose here is to automatically search for
increasingly complex artifacts in an open-ended fashion. Compared to other
environments used to study open-endedness, Minecraft allows the construction of
almost any kind of structure, including actuated machines with circuits and
mechanical components. We present initial baseline results in evolving simple
Minecraft creations through both interactive and automated evolution. While
evolution succeeds when tasked to grow a structure towards a specific target,
it is unable to find a solution when rewarded for creating a simple machine
that moves. Thus, EvoCraft offers a challenging new environment for automated
search methods (such as evolution) to find complex artifacts that we hope will
spur the development of more open-ended algorithms. A Python implementation of
the EvoCraft framework is available at:
https://github.com/real-itu/Evocraft-py.
|
String theory compactification involves manifolds with multiple warp factors.
For cosmological applications, one often introduces a short, high-energy
inflationary throat, and a long,low-energy Standard Model throat. It is assumed
that at the end of inflation,the excited Kaluza-Klein modes from the
Inflationary throat tunnel to the SM throat and reheat Standard Model degrees
of freedom, which are attached to probe brane(s). However, the huge hierarchy
of energy scales can result in a highly dynamic transition of the throat
geometry. We point out that in such a cosmological scenario the Standard Model
throat (together with SM brane) will be cloaked by a Schwarzschild horizon,
produced by the Kaluza-Klein modes tunneling from the short throat. The Black
Brane formation is dual to the first order chiral phase transition of the
cascading gauge theory. We calculate the critical energy density corresponding
the formation of the the BH horizon in the long throat. We discuss the duality
between "Black Universe" cosmology and an expanding universe driven by the hot
gauge theory radiation. We address the new problem of the hierarchical
multiple-throat scenarios: SM brane disappearance after the decay of the BH
horizon.
|
Consider the sample path of a one-dimensional diffusion for which the
diffusion coefficient is given and where the drift may take on one of two
values: $\mu_0$ or $\mu_1$. Suppose that the signal-to-noise ratio (defined as
the difference between the two possible drifts divided by the diffusion
coefficient) is non-constant. Given an initial state for the observed process,
we consider a minimax formulation of the Wiener sequential testing problem for
detecting the correct drift coefficient as soon as possible and with minimal
probabilities of incorrect terminal decisions. We solve the problem in the
Bayesian formulation, under any prior probabilities of the process having drift
$\mu_0$ or $\mu_1$, when the passage of time is penalized linearly. In the case
where the signal-to-noise ratio is assumed constant, we obtain an explicit
formula for the least favorable distribution.
|
We provide sharp two-sided estimates of the Fourier-Bessel heat kernel and we
give sharp two-sided estimates of the transition probability density for the
Bessel process in (0,1) killed at 1 and killed or reflected at 0.
|
The surface Hamiltonian for a spin zero particle that is pinned to a surface
by letting the thickness of a layer surrounding the surface go to zero --
assuming a strong normal force -- is constructed. The new approach we follow to
achieve this is to start with an expression for the 3D momentum operators whose
components along the surface and the normal to the surface are separately
Hermitian. The normal part of the kinetic energy operator is a Hermitian
operator in this case. When this operator is dropped and the thickness of the
layer is set to zero, one automatically gets the Hermitian surface Hamiltonian
that contains the geometric potential term as expected. Hamiltonians for both a
neutral and a charged particle in an electromagnetic field are constructed. We
show that a Hermitian surface and normal momenta emerge automatically once one
symmetrizes the usual normal and surface momentum operators. The present
approach makes it manifest that the geometrical potential originates from the
term that is added to the surface momentum operator to render it Hermitian;
this term itself emerges from symmetrization/ordering of differential momentum
operators in curvilinear coordinates. We investigate the connection between
this approach and the similar approach of Jenssen and Koppe and Costa ( the so
called Thin-Layer Quantization (TLQ)). We note that the critical transformation
of the wavefunction introduced there before taking the thickness of the layer
to zero actually -- while not noted explicitly stated by the authors -- renders
each of the surface and normal kinetic energy operators Hermitian by itself,
which is just what our approach does from the onset.
|
This paper puts forward a possible new indicator for the presence of
moderately advanced civilizations on transiting exoplanets. The idea is to
examine the region of space around a planet where potential geostationary or
geosynchronous satellites would orbit (herafter, the Clarke exobelt).
Civilizations with a high density of devices and/or space junk in that region,
but otherwise similar to ours in terms of space technology (our working
definition of "moderately advanced"), may leave a noticeable imprint on the
light curve of the parent star. The main contribution to such signature comes
from the exobelt edge, where its opacity is maximum due to geometrical
projection. Numerical simulations have been conducted for a variety of possible
scenarios. In some cases, a Clarke exobelt with a fractional face-on opacity of
~1E-4 would be easily observable with existing instrumentation. Simulations of
Clarke exobelts and natural rings are used to quantify how they can be
distinguished by their light curve.
|
Error and erasure exponents for the broadcast channel with degraded message
sets are analyzed. The focus of our error probability analysis is on the main
receiver where, nominally, both messages are to be decoded. A two-step decoding
algorithm is proposed and analyzed. This receiver first attempts to decode both
messages, failing which, it attempts to decode only the message representing
the coarser information, i.e., the cloud center. This algorithm reflects the
intuition that we should decode both messages only if we have confidence in the
estimates; otherwise one should only decode the coarser information. The
resulting error and erasure exponents, derived using the method of types, are
expressed in terms of a penalized form of the modified random coding error
exponent.
|
A simple graph $G=(V,E)$ on $n$ vertices is said to be recursively
partitionable (RP) if $G \simeq K_1$, or if $G$ is connected and satisfies the
following recursive property: for every integer partition $a_1, a_2, \dots,
a_k$ of $n$, there is a partition $\{A_1, A_2, \dots, A_k\}$ of $V$ such that
each $|A_i|=a_i$, and each induced subgraph $G[A_i]$ is RP ($1\leq i \leq k$).
We show that if $S$ is a vertex cut of an RP graph $G$ with $|S|\geq 2$, then
$G-S$ has at most $3|S|-1$ components. Moreover, this bound is sharp for
$|S|=3$. We present two methods for constructing new RP graphs from old. We use
these methods to show that for all positive integers $s$, there exist
infinitely many RP graphs with an $s$-vertex cut whose removal leaves $2s+1$
components. Additionally, we prove a simple necessary condition for a graph to
have an RP spanning tree, and we characterise a class of minimal 2-connected RP
graphs.
|
Echocardiography video is a primary modality for diagnosing heart diseases,
but the limited data poses challenges for both clinical teaching and machine
learning training. Recently, video generative models have emerged as a
promising strategy to alleviate this issue. However, previous methods often
relied on holistic conditions during generation, hindering the flexible
movement control over specific cardiac structures. In this context, we propose
an explainable and controllable method for echocardiography video generation,
taking an initial frame and a motion curve as guidance. Our contributions are
three-fold. First, we extract motion information from each heart substructure
to construct motion curves, enabling the diffusion model to synthesize
customized echocardiography videos by modifying these curves. Second, we
propose the structure-to-motion alignment module, which can map semantic
features onto motion curves across cardiac structures. Third, The
position-aware attention mechanism is designed to enhance video consistency
utilizing Gaussian masks with structural position information. Extensive
experiments on three echocardiography datasets show that our method outperforms
others regarding fidelity and consistency. The full code will be released at
https://github.com/mlmi-2024-72/ECM.
|
The development of Urdu scene text detection, recognition, and Visual
Question Answering (VQA) technologies is crucial for advancing accessibility,
information retrieval, and linguistic diversity in digital content,
facilitating better understanding and interaction with Urdu-language visual
data. This initiative seeks to bridge the gap between textual and visual
comprehension. We propose a new multi-task Urdu scene text dataset comprising
over 1000 natural scene images, which can be used for text detection,
recognition, and VQA tasks. We provide fine-grained annotations for text
instances, addressing the limitations of previous datasets for facing
arbitrary-shaped texts. By incorporating additional annotation points, this
dataset facilitates the development and assessment of methods that can handle
diverse text layouts, intricate shapes, and non-standard orientations commonly
encountered in real-world scenarios. Besides, the VQA annotations make it the
first benchmark for the Urdu Text VQA method, which can prompt the development
of Urdu scene text understanding. The proposed dataset is available at:
https://github.com/Hiba-MeiRuan/Urdu-VQA-Dataset-/tree/main
|
We propose a detuned Fabry-Perot cavity, pumped through both the mirrors, as
\textit{a toy model} of the gravitational-wave (GW) detector partially free
from displacement noise of the test masses. It is demonstrated that the noise
of cavity mirrors can be eliminated, but the one of lasers and detectors
cannot. The isolation of the GW signal from displacement noise of the mirrors
is achieved in a proper linear combination of the cavity output signals. The
construction of such a linear combination is possible due to the difference
between the reflected and transmitted output signals of detuned cavity. We
demonstrate that in low-frequency region the obtained displacement-noise-free
response signal is much stronger than the $f^3_{\textrm{gw}}$-limited
sensitivity of displacement-noise-free interferometers recently proposed by S.
Kawamura and Y. Chen. However, the loss of the resonant gain in the noise
cancelation procedure results is the sensitivity limitation of our toy model by
displacement noise of lasers and detectors.
|
We present an analysis of the merging cluster MACS J1149.5+2223 using
archival imaging from Subaru/Suprime-Cam and multi-object spectroscopy from
Keck/DEIMOS and Gemini/GMOS. We employ two and three dimensional substructure
tests and determine that MACS J1149.5+2223 is composed of two separate mergers
between three subclusters occurring $\sim$1 Gyr apart. The primary merger gives
rise to elongated X-ray morphology and a radio relic in the southeast. The
brightest cluster galaxy is a member of the northern subcluster of the primary
merger. This subcluster is very massive
(16.7$^{+\text{1.25}}_{-\text{1.60}}\times\text{10}^{\text{14}}$ M$_{\odot}$).
The southern subcluster is also very massive
(10.8$^{+\text{3.37}}_{-\text{3.54}}\times\text{10}^{\text{14}}$ M$_{\odot}$),
yet it lacks an associated X-ray surface brightness peak, and it has been
unidentified previously despite the detailed study of this \emph{Frontier
Field} cluster. A secondary merger is occurring in the north along the line of
sight with a third, less massive, subcluster
(1.20$^{+\text{0.19}}_{-\text{0.34}}\times\text{10}^{\text{14}}$ M$_{\odot}$).
We perform a Monte Carlo dynamical analysis on the main merger and estimate a
collision speed at pericenter of 2770$^{+\text{610}}_{-\text{310}}$ km
s$^{-\text{1}}$. We show the merger to be returning from apocenter with core
passage occurring 1.16$^{+\text{0.50}}_{-\text{0.25}}$ Gyr before the observed
state. We identify the line of sight merging subcluster in a strong lensing
analysis in the literature and show that it is likely bound to MACS J1149
despite having reached an extreme collision velocity of $\sim$4000 km
s$^{-\text{1}}$.
|
Engineered quantum systems allow us to observe phenomena that are not easily
accessible naturally. The LEGO-like nature of superconducting circuits makes
them particularly suited for building and coupling artificial atoms. Here, we
introduce an artificial molecule, composed of two strongly coupled fluxonium
atoms, which possesses a tunable magnetic moment. Using an applied external
flux, one can tune the molecule between two regimes: one in which the
ground-excited state manifold has a magnetic dipole moment and one in which the
ground-excited state manifold has only a magnetic quadrupole moment. By varying
the applied external flux, we find the coherence of the molecule to be limited
by local flux noise. The ability to engineer and control artificial molecules
paves the way for building more complex circuits for protected qubits and
quantum simulation.
|
Virtual screening (VS) is widely used during computational drug discovery to
reduce costs. Chemogenomics-based virtual screening (CGBVS) can be used to
predict new compound-protein interactions (CPIs) from known CPI network data
using several methods, including machine learning and data mining. Although
CGBVS facilitates highly efficient and accurate CPI prediction, it has poor
performance for prediction of new compounds for which CPIs are unknown. The
pairwise kernel method (PKM) is a state-of-the-art CGBVS method and shows high
accuracy for prediction of new compounds. In this study, on the basis of link
mining, we improved the PKM by combining link indicator kernel (LIK) and
chemical similarity and evaluated the accuracy of these methods. The proposed
method obtained an average area under the precision-recall curve (AUPR) value
of 0.562, which was higher than that achieved by the conventional Gaussian
interaction profile (GIP) method (0.425), and the calculation time was only
increased by a few percent.
|
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.
|
One key difference in current energy loss models lies in the treatment of the
Altarelli-Parisi, AP, splitting functions. It has been shown that the shared
momentum fraction, henceforth called Jet Splitting Function $z_g$ as determined
by the SoftDrop grooming process can be made a Sudakov-safe measurement of the
symmetrized AP functions in p+p collisions. The STAR collaboration presents the
first $z_g$ measurements at $\sqrt{s_{NN}}=200$ GeV in p+p and Au+Au
collisions, where in Au+Au we use the specific di-jet selection introduced in
our previous momentum imbalance measurement. For a jet resolution parameter of
$R=0.4$, these di-jet pairs were found to be significantly imbalanced with
respect to p+p, yet regained balance when all soft constituents were included.
We find that within uncertainties there are no signs of a modified Jet
Splitting Function on trigger or recoil side of this di-jet selection.
|
Many AI applications rely on knowledge encoded in a locigal knowledge base
(KB). The most essential benefit of such logical KBs is the opportunity to
perform automatic reasoning which however requires a KB to meet some minimal
quality criteria such as consistency. Without adequate tool assistance, the
task of resolving such violated quality criteria in a KB can be extremely hard,
especially when the problematic KB is large and complex. To this end,
interactive KB debuggers have been introduced which ask a user queries whether
certain statements must or must not hold in the intended domain. The given
answers help to gradually restrict the search space for KB repairs.
Existing interactive debuggers often rely on a pool-based strategy for query
computation. A pool of query candidates is precomputed, from which the best
candidate according to some query quality criterion is selected to be shown to
the user. This often leads to the generation of many unnecessary query
candidates and thus to a high number of expensive calls to logical reasoning
services. We tackle this issue by an in-depth mathematical analysis of diverse
real-valued active learning query selection measures in order to determine
qualitative criteria that make a query favorable. These criteria are the key to
devising efficient heuristic query search methods. The proposed methods enable
for the first time a completely reasoner-free query generation for interactive
KB debugging while at the same time guaranteeing optimality conditions, e.g.
minimal cardinality or best understandability for the user, of the generated
query that existing methods cannot realize.
Further, we study different relations between active learning measures. The
obtained picture gives a hint about which measures are more favorable in which
situation or which measures always lead to the same outcomes, based on given
types of queries.
|
Swift discovered GRB 050713A and slewed promptly to begin observing with its
narrow field instruments 72.6 seconds after the burst onset, while the prompt
gamma-ray emission was still detectable in the BAT. Simultaneous emission from
two flares is detected in the BAT and XRT. This burst marks just the second
time that the BAT and XRT have simultaneously detected emission from a burst
and the first time that both instruments have produced a well sampled,
simultaneous dataset covering multiple X-ray flares. The temporal rise and
decay parameters of the flares are consistent with the internal shock
mechanism. In addition to the Swift coverage of GRB 050713A, we report on the
Konus-Wind (K-W) detection of the prompt emission in the energy range 18-1150
keV, an upper limiting GeV measurement of the prompt emission made by the MAGIC
imaging atmospheric Cherenkov telescope and XMM-Newton observations of the
afterglow. Simultaneous observation between Swift XRT and XMM-Newton produce
consistent results, showing a break in the lightcurve at T+~15ks. Together,
these four observatories provide unusually broad spectral coverage of the
prompt emission and detailed X-ray follow-up of the afterglow for two weeks
after the burst trigger. Simultaneous spectral fits of K-W with BAT and BAT
with XRT data indicate that an absorbed broken powerlaw is often a better fit
to GRB flares than a simple absorbed powerlaw. These spectral results together
with the rapid temporal rise and decay of the flares suggest that flares are
produced in internal shocks due to late time central engine activity.
|
A new framework for analyzing Fejer convergent algorithms is presented. Using
this framework we define a very general class of Fejer convergent algorithms
and establish its convergence properties. We also introduce a new definition of
approximations of resolvents which preserve some useful features of the exact
resolvent, and use this concept to present an unifying view of the
Forward-Backward splitting method, Tseng's Modified Forward-Backward splitting
method and Korpelevich's method. We show that methods based on families of
approximate resolvents fall within the aforementioned class of Fejer convergent
methods. We prove that such approximate resolvents are the iteration maps of
the Hybrid Proximal-Extragradient method.
|
In this paper we prove some new Stone-type duality theorems for some
subcategories of the category $\ZLC$ of locally compact zero-dimensional
Hausdorff spaces and continuous maps. These theorems are new even in the
compact case. They concern the cofull subcategories $\SkeZLC$, $\QPZLC$,
$\OZLC$ and $\OPZLC$ of the category $\ZLC$ determined, respectively, by the
skeletal maps, by the quasi-open perfect maps, by the open maps and by the open
perfect maps. In this way, the zero-dimensional analogues of Fedorchuk Duality
Theorem and its generalization are obtained. Further, we characterize the
injective and surjective morphisms of the category $\HLC$ of locally compact
Hausdorff spaces and continuous maps, as well as of the category $\ZLC$, and of
some their subcategories, by means of some properties of their dual morphisms.
This generalizes some well-known results of M. Stone and de Vries. An analogous
problem is investigated for the homeomorphic embeddings, dense embeddings,
LCA-embeddings etc., and a generalization of a theorem of Fedorchuk is
obtained. Finally, in analogue to some well-known results of M. Stone, the dual
objects of the open, regular open, clopen, closed, regular closed etc. subsets
of a space $X\in\card{\HLC}$ or $X\in\card{\ZLC}$ are described by means of the
dual objects of $X$; some of these results (e.g., for regular closed sets) are
new even in the compact case.
|
We consider spin relaxation of finite-size spin chains exchanged coupled with
a one dimensional (1D) electron gas at the edge of a Quantum Spin Hall (QSH)
insulator. Spin lifetimes can be enhanced due to two independent mechanisms.
First, the suppression of spin-flip forward scattering inherent in the spin
momentum locking of the QSH edges. Second, the reduction of spin-flip backward
scattering due to destructive interference of the quasiparticle exchange,
modulated by $k_F d$, where $d$ is the inter-spin distance and $k_F$ is the
Fermi wavenumber of the electron gas. We show that the spin lifetime of the
$S=1/2$ ground state of odd-numbered chains of antiferromagnetically (AFM)
coupled $S=1/2$ spins can be increased more than 4 orders of magnitude by
properly tuning the product $k_Fd$ and the spin size $N$, in strong contrast
with the 1D case. Possible physical realizations together with some potential
issues are also discussed.
|
A potassium alumina borosilicate glass with the composition
13K2O*13Al2O3*16B2O3*43SiO2*15Fe2O3-x was melted using Fe2O3 as raw material.
The melt was dumped from a Pt-crucible with a downpipe in water which resulted
in the formation of phase separated droplets with a size of around 100 - 150
nm. In this droplets, magnetite crystals with a size of around 10-20 nm were
observed. These magnetite nanoparticles with superparamagnetic behaviour are
arranged to larger aggregates. This leads to a higher effective magnetic
radius. According to magnetisation measurements the particles show hysteresis.
The ratio of remanent vs. saturation magnetisation is not as high as it is
necessary for uniaxial anisotropy. It is possible to elude the phase
separations by cooking the pulverized glass in concentrated sodium hydroxide.
Additional temperature dependent magnetorelaxometry (TMRX) measurements show in
the distribution of the relaxation of magnetic moments over the course of
temperature two peaks at 13 and 39 K. According to an interparticle distance
smaller than 5 dC (the core diameter) could that be a result of strong magnetic
interactions. Other magnetic relaxation processes also explain this measured
effect.
|
The second-order correlation function of light $g^{(2)}(\tau)$ constitutes a
pivotal tool to quantify the quantum behavior of an emitter and in turn its
potential for quantum information applications. The experimentally accessible
time resolution of $g^{(2)}(\tau)$ is usually limited by the jitter of
available single photon detectors. Here, we present a versatile technique
allowing to measure $g^{(2)}(\tau)$ from a large variety of light signals with
a time resolution given by the pulse length of a mode-locked laser. The
technique is based on frequency upconversion in a nonlinear waveguide, and we
analyze its properties and limitations by modeling the pulse propagation and
the frequency conversion process .We measure $g^{(2)}(\tau)$ from various
signals including light from a quantum emitter - a confined exciton-polariton
structure - revealing its quantum signatures at a scale of a few picoseconds
and demonstrating the capability of the technique.
|
In a recent paper on a study of the Sylow 2-subgroups of the symmetric group
with 2^n elements it has been show that the growth of the first (n-2)
consecutive indices of a certain normalizer chain is linked to the sequence of
partitions of integers into distinct parts. Unrefinable partitions into
distinct parts are those in which no part x can be replaced with integers whose
sum is x obtaining a new partition into distinct parts. We prove here that the
(n-1)-th index of the previously mentioned chain is related to the number of
unrefinable partitions into distinct parts satisfying a condition on the
minimal excludant.
|
This paper investigates the structural changes in the parameters of
first-order autoregressive models by analyzing the edge eigenvalues of the
precision matrices. Specifically, edge eigenvalues in the precision matrix are
observed if and only if there is a structural change in the autoregressive
coefficients. We demonstrate that these edge eigenvalues correspond to the
zeros of some determinantal equation. Additionally, we propose a consistent
estimator for detecting outliers within the panel time series framework,
supported by numerical experiments.
|
Model error covariances play a central role in the performance of data
assimilation methods applied to nonlinear state-space models. However, these
covariances are largely unknown in most of the applications. A misspecification
of the model error covariance has a strong impact on the computation of the
posterior probability density function, leading to unreliable estimations and
even to a total failure of the assimilation procedure. In this work, we propose
the combination of the Expectation-Maximization algorithm (EM) with an
efficient particle filter to estimate the model error covariance, using a batch
of observations. Based on the EM algorithm principles, the proposed method
encompasses two stages: the expectation stage, in which a particle filter is
used with the present estimate of the model error covariance as given to find
the probability density function that maximizes the likelihood, followed by a
maximization stage in which the expectation under the probability density
function found in the expectation step is maximized as a function of the
elements of the model error covariance. This novel algorithm here presented
combines the EM with a fixed point algorithm and does not require a particle
smoother to approximate the posterior densities. We demonstrate that the new
method accurately and efficiently solves the linear model problem. Furthermore,
for the chaotic nonlinear Lorenz-96 model the method is stable even for
observation error covariance 10 times larger than the estimated model error
covariance matrix, and also that it is successful in high-dimensional
situations where the dimension of the estimated matrix is 1600.
|
We give conditions under which the demand function of a strictly convex
preference relation can be constructed.
|
Recently, \citet{SuttonMW15} introduced the emphatic temporal differences
(ETD) algorithm for off-policy evaluation in Markov decision processes. In this
short note, we show that the projected fixed-point equation that underlies ETD
involves a contraction operator, with a $\sqrt{\gamma}$-contraction modulus
(where $\gamma$ is the discount factor). This allows us to provide error bounds
on the approximation error of ETD. To our knowledge, these are the first error
bounds for an off-policy evaluation algorithm under general target and behavior
policies.
|
The unprecedented precision of experimental measurements at the Large Hadron
Collider (LHC) and the increased statistics that will be reached in the
High-Luminosity phase of the LHC (HL-LHC) are pushing the phenomenology
community to a new precision frontier, in which new challenges present
themselves and new questions arise. A key ingredients of theoretical
predictions at hadron colliders are the Parton Distribution Functions (PDFs) of
the proton. This contribution highlights some of the new developments in the
determination of PDFs from a global set of experimental data, from approximate
N3LO PDFs and the inclusion of theory uncertainties in PDF fits, to the
realisation of the non trivial interplay between parton densities at large-x
and possible signals of New Physics in high energy tails of the distributions,
which highlights the synergy between high energy and low energy experimental
programs.
|
The rapidly increasing capabilities of large language models (LLMs) raise an
urgent need to align AI systems with diverse human preferences to
simultaneously enhance their usefulness and safety, despite the often
conflicting nature of these goals. To address this important problem, a
promising approach is to enforce a safety constraint at the fine-tuning stage
through a constrained Reinforcement Learning from Human Feedback (RLHF)
framework. This approach, however, is computationally expensive and often
unstable. In this work, we introduce Constrained DPO (C-DPO), a novel extension
of the recently proposed Direct Preference Optimization (DPO) approach for
fine-tuning LLMs that is both efficient and lightweight. By integrating dual
gradient descent and DPO, our method identifies a nearly optimal trade-off
between helpfulness and harmlessness without using reinforcement learning.
Empirically, our approach provides a safety guarantee to LLMs that is missing
in DPO while achieving significantly higher rewards under the same safety
constraint compared to a recently proposed safe RLHF approach.
Warning: This paper contains example data that may be offensive or harmful.
|
We study the phase diagram of the BCSOS model with an extended interaction
range using transfer matrix techniques, pertaining to the (100) surface of
single component fcc and bcc crystals. The model shows a 2x2 reconstructed
phase and a disordered flat phase. The deconstruction transition between these
phases merges with a Kosterlitz-Thouless line, showing an interplay of Ising
and Gaussian degrees of freedom. As in studies of the fully frustrated XY
model, exponents deviating from Ising are found. We conjecture that
tri-critical Ising behavior may be a possible explanation for the non-Ising
exponents found in those models.
|
This paper implements a traffic signal control system by using real-time
traffic flow feedback. This system is designed to deal with two-lane
intersections. We construct an experiment field similar to the roads and
drivers in Taiwan using an autonomous simulation software called Virtual Test
Drive (VTD) released by MSC Software. We erect four cameras on the side of the
roads to get the image of the intersection, then transfer the image information
into traffic flow information. Analyze the traffic information in each lane by
using Greenshields traffic flow model. Control the traffic signals by using
Webster's method to increase the performance and soothe the traffic.
|
We are concerned with the construction of global-in-time strong solutions for
the incompressible Vlasov-Navier-Stokes systemin the whole three-dimensional
space. One of our goals is to establish that small initial velocities with
critical Sobolev regularity and sufficiently well localized initial kinetic
distribution functions give rise to global and unique solutions. This
constitutes an extension of the celebrated result for the
incompressibleNavier-Stokes equations (NS) that has been established in 1964 by
Fujita and Kato. If in addition the initial velocity is integrable, we
establish that the total energy of the system decays to 0 with the optimal rate
t^{-3/2}, like for the weak solutions of (NS). Our results partly rely on the
use of a higher order energy functional that controls the regularity $H^1$ of
the velocityand seems to have been first introduced by Li, Shou and Zhang in
the contextof nonhomogeneous Vlasov-Navier-Stokes system. In the small data
case, we show that this energy functional decays with the rate t^{-5/2}.
|
Strong interactions between surface plasmons in ultra-compact nanocavities
and excitons in two dimensional materials have attracted wide interests for its
prospective realization of polariton devices at room temperature. Here, we
propose a continuous transition from weak coupling to strong coupling between
excitons in MoS2 monolayer and highly localized plasmons in ultra-compact
nanoantenna. The nanoantenna is assembled by a silver nanocube positioned over
a gold film and separated by a dielectric spacer layer. We observed a 1570-fold
enhancement in the photoluminescence at weak coupling regime in hybrid
nanocavities with thick spacer layers. The interaction between excitons and
plasmons is then directly prompted to strong coupling regime by shrinking down
the thickness of spacer layer. Room temperature formation of polaritons with
Rabi splitting up to 190 meV was observed, which is the largest plasmon-exciton
Rabi splitting reported in two dimensional materials. Numerical calculations
quantified the relation between coupling strength, local density of states and
spacer thickness, and revealed the transition between weak coupling and strong
coupling in nanocavities. The findings in this work offer a guideline for
feasible designs of plasmon-exciton interaction systems with gap plasmonic
cavities.
|
It is well known that the equation $x'(t)=Ax(t)+f(t)$, where $A$ is a square
matrix, has a unique bounded solution $x$ for any bounded continuous free term
$f$, provided the coefficient $A$ has no eigenvalues on the imaginary axis.
This solution can be represented in the form \begin{equation*}
x(t)=\int_{-\infty}^{\infty}\mathcal G(t-s)x(s)\,ds. \end{equation*} The kernel
$\mathcal G$ is called Green's function. In the paper, a representation of
Green's function in the form of the Newton interpolating polynomial is used for
approximate calculation of $\mathcal G$. An estimate of the sensitivity of the
problem is given.
|
Explaining the formation and evolution of galaxies is one of the most
challenging problems in observational cosmology. Many observations suggest that
galaxies we see today could have evolved from the merging of smaller
subsystems. Evolution of galaxies tells us how the mass or number density of
the lens varies with cosmic time. Merging between the galaxies and the infall
of surrounding mass into galaxies are two possible processes that can change
the comoving number density of galaxies and/or their mass. We consider five
different evolutionary models of galaxies .These models are: Non evolutionary
model, Guiderdoni and Volmerange model, fast merging, slow merging and mass
accretion model. We study the gravitational lens image separation distribution
function for these models of evolving galaxies. A comparison with data for
lensed quasars taken from the HST Snapshot Survey rules out the fast merging
model completely as this model produces a large number of small-separation
lenses. It is possible that the mass accretion model and the non evolutionary
model of galaxies may be able to explain the small angle separations.
|
For a general class of priors based on random series basis expansion, we
develop the Bayes Lepski's method to estimate unknown regression function. In
this approach, the series truncation point is determined based on a stopping
rule that balances the posterior mean bias and the posterior standard
deviation. Equipped with this mechanism, we present a method to construct
adaptive Bayesian credible bands, where this statistical task is reformulated
into a problem in geometry, and the band's radius is computed based on finding
the volume of certain tubular neighborhood embedded on a unit sphere. We
consider two special cases involving B-splines and wavelets, and discuss some
interesting consequences such as the uncertainty principle and self-similarity.
Lastly, we show how to program the Bayes Lepski stopping rule on a computer,
and numerical simulations in conjunction with our theoretical investigations
concur that this is a promising Bayesian uncertainty quantification procedure.
|
We study non-linear sigma models on target manifolds with constant (positive
or negative) curvature using the functional renormalization group and the
background field method. We pay particular attention to the splitting Ward
identities associated to the invariance under reparametrization of the
background field. Implementing these Ward identities imposes to use the
curvature as a formal expansion parameter, which allows us to close the flow
equation of the (scale-dependent) effective action consistently to first order
in the curvature. We shed new light on previous work using the background field
method.
|
Using extensive numerical studies we demonstrate that absolute negative
mobility of a Brownian particle (i.e. the net motion into the direction
opposite to a constant biasing force acting around zero bias) does coexist with
anomalous diffusion. The latter is characterized in terms of a nonlinear
scaling with time of the mean-square deviation of the particle position. Such
anomalous diffusion covers "coherent" motion (i.e. the position dynamics x(t)
approaches in evolving time a constant dispersion), ballistic diffusion,
subdiffusion, superdiffusion and hyperdiffusion. In providing evidence for this
coexistence we consider a paradigmatic model of an inertial Brownian particle
moving in a one-dimensional symmetric periodic potential being driven by both
an unbiased time-periodic force and a constant bias. This very setup allows for
various sorts of different physical realizations.
|
Over the past two decades, there has been a growing interest in control
systems research to transition from model-based methods to data-driven
approaches. In this study, we aim to bridge a divide between conventional
model-based control and emerging data-driven paradigms grounded in Willem's
fundamental lemma. Specifically, we study how input/output data from two
separate systems can be manipulated to represent the behavior of interconnected
systems, either connected in series or through feedback. Using these results,
this paper introduces the Internal Behavior Control (IBC), a new control
strategy based on the well-known Internal Model Control (IMC) but viewed under
the lens of Behavioral System Theory. Similar to IMC, the IBC is easy to tune
and results in perfect tracking and disturbance rejection but, unlike IMC, does
not require a parametric model of the dynamics. We present two approaches for
IBC implementation: a component-by-component one and a unified one. We compare
the two approaches in terms of filter design, computations, and memory
requirements.
|
Object detection from images captured by Unmanned Aerial Vehicles (UAVs) is
becoming increasingly useful. Despite the great success of the generic object
detection methods trained on ground-to-ground images, a huge performance drop
is observed when they are directly applied to images captured by UAVs. The
unsatisfactory performance is owing to many UAV-specific nuisances, such as
varying flying altitudes, adverse weather conditions, dynamically changing
viewing angles, etc. Those nuisances constitute a large number of fine-grained
domains, across which the detection model has to stay robust. Fortunately, UAVs
will record meta-data that depict those varying attributes, which are either
freely available along with the UAV images, or can be easily obtained. We
propose to utilize those free meta-data in conjunction with associated UAV
images to learn domain-robust features via an adversarial training framework
dubbed Nuisance Disentangled Feature Transform (NDFT), for the specific
challenging problem of object detection in UAV images, achieving a substantial
gain in robustness to those nuisances. We demonstrate the effectiveness of our
proposed algorithm, by showing state-of-the-art performance (single model) on
two existing UAV-based object detection benchmarks. The code is available at
https://github.com/TAMU-VITA/UAV-NDFT.
|
We consider the radial Dirac operator with compactly supported potentials. We
study resonances as the poles of scattering matrix or equivalently as the zeros
of modified Fredholm determinant. We obtain the following properties of the
resonances: 1) asymptotics of counting function, 2) in the massless case we get
the trace formula in terms of resonances.
|
We investigate possible signatures of feedback from galactic superwinds on
the metallicity of the Lyman alpha forest, using a set of high resolution
hydrodynamic simulations of a Lambda cold dark matter model. Simulations
produce metals self-consistently, based on one single parameter, the metal
yield, which in turn is constrained by metallicity in the intra-cluster gas. We
follow metals as a separate density species. For the metallicity of Lyman alpha
clouds with column density of N_{HI}~10^{14.5}-10^{15.5}/cm^2 at z=2-4 we find
reasonable agreement between simulations, both with and without GSW, and
observations (Schaye et al). A unique signature and sensitive test of GSW is,
however, provided by lower density regions with gas density of \rho/<\rho> =
0.01-1.0 and a corresponding column density of 10^{12}-10^{14}/cm^2. Without
GSW we predict that both the mean and median metallicity of \lya clouds in this
column density range at z=2-4 should have Z<10^{3}Zsun, since these small
systems support little star formation. GSW contaminate these regions, however,
and also there is a significant fraction (~25%) of Lyman alpha clouds in this
column density range which have a high metallicity excess of 10^{-2}Zsun,
resulting in a mean metallicity of ~10^{-2}Zsun. In addition, we find that
there is a minimum in the median metallicity for clouds of
N_{HI}~10^{13}-10^{14}/cm^2 in the case with GSW, whereas without GSW the
metallicity decreases monotonically and rapidly with decreasing column density.
Finally, we predict that the ratio of secondary (e.g., N) to primary metals
(e.g., O,C) is expected to be smaller by a factor of 10 in clouds of
N_{HI}~10^{14.5}/cm^2 compared to that in large galaxies; this factor increases
to >50 for N_{HI}< 10^{13.5}/cm^2.
|
We show from general principles that there must be a center of mass energy,
$\sqrt s_0$, where the polarization asymmetry $A=\Delta \sigma({\gamma e \to W
\nu })/ \sigma({\gamma e \to W \nu })$ for circularly-polarized photon and
electron beams vanishes. In the case of the Standard Model, the crossing point
where the asymmetry changes sign occurs in Born approximation at $\sqrt
s_{\gamma e} = 3.1583\ldots M_W \simeq 254$ GeV. We demonstrate the sensitivity
of the position of the polarization asymmetry zero to modifications of the SM
trilinear $\gamma W W$ coupling. Given reasonable assumptions for the
luminosity and energy range for the Next Linear Collider(NLC) with a
backscattered laser beam, we show that the zero point, $\sqrt s_0$, of the
polarization asymmetry may be determined with sufficient precision to constrain
the anomalous couplings of the $W$ to better than the 1\% level at $95\%$ CL.
In addition to the fact that only a limited range of energy is required, the
polarization asymmetry measurements have the important advantage that many of
the systematic errors cancel in taking cross section ratios. The position of
the zero thus provides an additional weapon in the arsenal used to probe
anomalous trilinear gauge couplings.
|
WE trace the beginning of symbolic dynamics--the study of the shift dynamical
system--as it arose from the use of coding to study recurrence and transitivity
properties of geodesics. The normal citations for the first appearance of
symbolic dynamics, Hadamard's 1898 paper and the 1938 and 1940 papers of Morse
and Hedlund, don't truly represent the abstract point of view associated with
the subject today. Based in part on the evidence of a 1941 letter from Hedlund
to Morse, we place the beginning of symbolic dynamics in a 1944 paper by
Hedlund.
|
The low frequency oscillatory relaxation of zonal potential perturbations is
studied numerically in the TJ-II stellarator (where it was experimentally
detected for the first time). It is studied in full global gyrokinetic
simulations of multi-species plasmas. The oscillation frequency obtained is
compared with predictions based on single-species simulations using simplified
analytical relations. It is shown that the frequency of this oscillation for a
multi-species plasma can be accurately obtained from single-species
calculations using extrapolation formulas. The damping of the oscillation and
the influence of the different inter-species collisions is studied in detail.
It is concluded that taking into account multiple kinetic ions and electrons
with impurity concentrations realistic for TJ-II plasmas allows to account for
the values of frequency and damping rate in zonal flows relaxations observed
experimentally.
|
We describe the asymptotic behavior of Palais-Smale sequences associated to
certain Yamabe-type equations on manifolds with boundary. We prove that each of
those sequences converges to a solution of the limit equation plus a finite
number of "bubbles" which are obtained by rescaling fundamental solutions of
the corresponding Euclidean equations.
|
Consider a linear regression model and suppose that our aim is to find a
confidence interval for a specified linear combination of the regression
parameters. In practice, it is common to perform a Durbin-Watson pretest of the
null hypothesis of zero first-order autocorrelation of the random errors
against the alternative hypothesis of positive first-order autocorrelation. If
this null hypothesis is accepted then the confidence interval centred on the
Ordinary Least Squares estimator is used; otherwise the confidence interval
centred on the Feasible Generalized Least Squares estimator is used. We provide
new tools for the computation, for any given design matrix and parameter of
interest, of graphs of the coverage probability functions of the confidence
interval resulting from this two-stage procedure and the confidence interval
that is always centred on the Feasible Generalized Least Squares estimator.
These graphs are used to choose the better confidence interval, prior to any
examination of the observed response vector.
|
We give the supersymmetric extension of exceptional field theory for
E$_{7(7)}$, which is based on a $(4+56)$-dimensional generalized spacetime
subject to a covariant constraint. The fermions are tensors under the local
Lorentz group ${\rm SO}(1,3)\times {\rm SU}(8)$ and transform as scalar
densities under the E$_{7(7)}$ (internal) generalized diffeomorphisms. The
supersymmetry transformations are manifestly covariant under these symmetries
and close, in particular, into the generalized diffeomorphisms of the
56-dimensional space. We give the fermionic field equations and prove
supersymmetric invariance. We establish the consistency of these results with
the recently constructed generalized geometric formulation of $D=11$
supergravity.
|
The purpose of this paper is to fill the gap between the classical treatment
of brittle fracture mechanics and the new idea of considering the crack
evolution as a free discontinuity problem. Griffith and Irwin criterions of
crack propagation are studied and transformed in order to be no longer
dependent on any prescription of the geometry of the crack during its
evolution. The inequality contained in theorem 6.1. represents the link between
generalized Irwin and Griffith criterions of brittle crack propagation. The
physical meaning of this inequality is explained in the last section.
Further information available at http://irmi.epfl.ch/cag/buliga_bfrac.html .
|
We develop a fast method for computing the electrostatic energy and forces
for a collection of charges in doubly-periodic slabs with jumps in the
dielectric permittivity at the slab boundaries. Our method achieves spectral
accuracy by using Ewald splitting to replace the original Poisson equation for
nearly-singular sources with a smooth far-field Poisson equation, combined with
a localized near-field correction. Unlike existing spectral Ewald methods,
which make use of the Fourier transform in the aperiodic direction, we recast
the problem as a two-point boundary value problem in the aperiodic direction
for each transverse Fourier mode, for which exact analytic boundary conditions
are available. We solve each of these boundary value problems using a fast,
well-conditioned Chebyshev method. In the presence of dielectric jumps,
combining Ewald splitting with the classical method of images results in
smoothed charge distributions which overlap the dielectric boundaries
themselves. We show how to preserve spectral accuracy in this case through the
use of a harmonic correction which involves solving a simple Laplace equation
with smooth boundary data. We implement our method on Graphical Processing
Units, and combine our doubly-periodic Poisson solver with Brownian Dynamics to
study the equilibrium structure of double layers in binary electrolytes
confined by dielectric boundaries. Consistent with prior studies, we find
strong charge depletion near the interfaces due to repulsive interactions with
image charges, which points to the need for incorporating polarization effects
in understanding confined electrolytes, both theoretically and computationally.
|
Yang-Mills theories undergo a deconfining phase transition at a critical
temperature. In lattice calculations the temporal Wilson loop and Z_3 order
parameter show above this temperature a behavior typical of deconfinement. A
quantity of interest in the study of this transition is the gluon propagator
and its evolution with temperature. This contribution describes the current
status of an investigation of the finite temperature gluon propagator in Landau
gauge. It analyzes the high temperature case. The resulting equations are
compared to the corresponding ones of three-dimensional Yang-Mills theory.
Under certain assumptions it is found that a kind of spatial "confinement" is
still present, even at very high temperatures.
|
The $\eta-\eta^{\prime}$ mixture is discussed in the chiral bag model to
calculate the pseudoscalar octet-singlet mixing angle consistent with the
experimental data. The color anomaly is taken into account with the modified
boundary conditions, which shows the relation between the $\eta^{\prime}$ mass
and the gluon condensate inside the chiral bag. We show, however, that
$\eta-\eta^{\prime}$ mixing angle can follow the Cheshire Cat Principle, i.e.,
insensitivity to the bag radius.
|
It has been noticed that the k-string observables can be expressed in terms
of the fundamental string ones. We identify a sufficient condition for a
generic gravity dual background which when satisfied the mapping can be done.
The condition is naturally related to a preserved quantity under the
T-dualities acting on the Dp-brane describing the high representation Wilson
loops. We also find the explicit relation between the observables of the heavy
k-quark and the single quark states. As an application to our generic study and
motivated by the fact that the anisotropic theories satisfy our condition, we
compute the width of the k-string in these theories to find that the
logarithmic broadening is still present, but the total result is affected by
the anisotropy of the space.
|
This paper presents a convergence analysis of a Krylov subspace spectral
(KSS) method applied to a 1-D wave equation in an inhomogeneous medium. It will
be shown that for sufficiently regular initial data, this KSS method yields
unconditional stability, spectral accuracy in space, and second-order accuracy
in time, in the case of constant wave speed and a bandlimited reaction term
coefficient. Numerical experiments that corroborate the established theory are
included, along with an investigation of generalizations, such as to higher
space dimensions and nonlinear PDEs, that features performance comparisons with
other Krylov subspace-based time-stepping methods. This paper also includes the
first stability analysis of a KSS method that does not assume a bandlimited
reaction term coefficient.
|
The experimental status is reviewed on the search for the chiral magnetic
effect (CME) in relativistic heavy-ion collisions. Emphasis is put on
background contributions to the CME-sensitive charge correlation measurements
and their effects on data interpretation.
|
We establish two exact sequences for the lattice cohomology associated with
non-degenerate plumbing graphs. The first is the analogue of the surgery exact
triangle proved by Ozsvath and Szabo for the Heegaard-Floer invariant HF^+; for
the lattice cohomology over Z_2-coefficients it was proved by J. Greene. Here
we prove it over the integers, and we supplement it by some additional
properties valid for negative definite graphs. The second exact sequence is an
adapted version which does not mix the classes of the characteristic elements
(spin^c-structures); it was partially motivated by the surgery formula for the
Seiberg-Witten invariant obtained by Braun and the author. For this we define
the `relative lattice cohomology' and we also determine its Euler
characteristic in terms of Seiberg-Witten invariants.
|
The Coronavirus, also known as the COVID-19 virus, has emerged in Wuhan China
since late November 2019. Since that time, it has been spreading at large-scale
until today all around the world. It is currently recognized as the world's
most viral and severe epidemic spread in the last twenty years, as compared to
Ebola 2014, MERS 2012, and SARS 2003. Despite being still in the middle of the
outbreak, there is an urgent need to understand the impact of COVID-19. The
objective is to clarify how it was spread so fast in a short time worldwide in
unprecedented fashion. This paper represents a first initiative to achieve this
goal, and it provides a comprehensive analytical study about the Coronavirus.
The contribution of this paper consists in providing descriptive and predictive
models that give insights into COVID-19 impact through the analysis of
extensive data updated daily for the outbreak in all countries. We aim at
answering several open questions: How does COVID-19 spread around the world?
What is its impact in terms of confirmed and death cases at the continent,
region, and country levels? How does its severity compare with other epidemic
outbreaks, including Ebola 2014, MERS 2012, and SARS 2003? Is there a
correlation between the number of confirmed cases and death cases? We present a
comprehensive analytics visualization to address the questions mentioned above.
To the best of our knowledge, this is the first systematic analytical papers
that pave the way towards a better understanding of COVID-19. The analytical
dashboards and collected data of this study are available online [1].
|
We consider new Abelian twists of Poincare algebra describing non-symmetric
generalization of the ones given in [1], which lead to the class of
Lie-deformed quantum Minkowski spaces. We apply corresponding twist
quantization in two ways: as generating quantum Poincare-Hopf algebra providing
quantum Poincare symmetries, and by considering the quantization which provides
Hopf algebroid describing the class of quantum relativistic phase spaces with
built-in quantum Poincare covariance. If we assume that Lorentz generators are
orbital i.e.do not describe spin degrees of freedom, one can embed the
considered generalized phase spaces into the ones describing the
quantum-deformed Heisenberg algebras.
|
Kinesin-8 motor proteins destabilize microtubules. Their absence during cell
division is associated with disorganized mitotic chromosome movements and
chromosome loss. Despite recent work studying effects of kinesin 8s on
microtubule dynamics, it remains unclear whether the kinesin-8 mitotic
phenotypes are consequences of their effect on microtubule dynamics, their
well-established motor activity, or additional unknown functions. To better
understand the role of kinesin-8 proteins in mitosis, we have studied the
effects of deletion of the fission-yeast kinesin-8 proteins Klp5 and Klp6 on
chromosome movements and spindle length dynamics. Aberrant microtubule-driven
kinetochore pushing movements and tripolar mitotic spindles occurred in cells
lacking Klp5 but not Klp6. Kinesin-8 deletion strains showed large fluctuations
in metaphase spindle length, suggesting a disruption of spindle length
stabilization. Comparison of our results from light microscopy with a
mathematical model suggests that kinesin-8 induced effects on microtubule
dynamics, kinetochore attachment stability, and sliding force in the spindle
can explain the aberrant chromosome movements and spindle length fluctuations
seen.
|
Facebook and other advertising platforms exploit users data for marketing
purposes by allowing advertisers to select specific users and target them (the
practice is being called micro-targeting). However, advertisers such as
Cambridge Analytica have maliciously used these targeting features to
manipulate users in the context of elections. The European Commission plans to
restrict or ban some targeting functionalities in the new European Democracy
Action Plan act to protect users from such harms. The difficulty is that we do
not know the economic impact of these restrictions on regular advertisers. In
this paper, to inform the debate, we take a first step by understanding who is
advertising on Facebook and how they use the targeting functionalities. For
this, we asked 890 U.S. users to install a monitoring tool on their browsers to
collect the ads they receive on Facebook and information about how these ads
were targeted. By matching advertisers on Facebook with their LinkedIn
profiles, we could see that 71% of advertisers are small and medium-sized
businesses with 200 employees or less, and they are responsible for 61% of ads
and 57% of ad impressions. Regarding micro-targeting, we found that only 32% of
small and medium-sized businesses and 30% of large-sized businesses
micro-target at least one of their ads. These results should not be interpreted
as micro-targeting not being useful as a marketing strategy, but rather that
advertisers prefer to outsource the micro-targeting task to ad platforms.
Indeed, Facebook is employing optimization algorithms that exploit user data to
decide which users should see what ads; which means ad platforms are performing
an algorithmic-driven micro-targeting. Hence, when setting restrictions,
legislators should take into account both the traditional advertiser-driven
micro-targeting as well as algorithmic-driven micro-targeting performed by ad
platforms.
|
Vectorization process focus on grouping pixels of a raster image into raw
line segments, and forming lines, polylines or poligons. To vectorize massive
raster images regarding resource and performane problems, weuse a distributed
HIPI image processing interface based on MapReduce approach. Apache Hadoop is
placed at the core of the framework. To realize such a system, we first define
mapper function, and then its input and output formats. In this paper, mappers
convert raster mosaics into vector counterparts. Reduc functions are not needed
for vectorization. Vector representations of raster images is expected to give
better performance in distributed computations by reducing the negative effects
of bandwidth problem and horizontal scalability analysis is done.
|
We compute the homotopy type of the space of T^n-equivariant symplectic
embeddings from the standard 2n-dimensional ball of some fixed radius into a
2n-dimensional symplectic-toric manifold M, and use this computation to define
a Z-valued step function on the positive real line which is an invariant of the
symplectic-toric type of M. We conclude with a discussion of the partially
equivariant case of this result.
|
The QCD vacuum is populated by instantons that correspond to the tunneling
processes in the vacuum. This mechanism creates the strong vacuum gluon fields.
As result, the QCD vacuum instantons induce very strong interactions between
light quarks, initially almost massless. Such a strong interactions bring a
large dynamical mass M of the light quarks and bound them to produce almost
massless pions in accordance with the spontaneous breaking of the chiral
symmetry (SBCS). On the other hand, the QCD vacuum instantons also interact
with heavy quarks and responsible for the generation of the heavy-heavy and
heavy-light quarks interactions, with a traces of the SBCS. If we take the
average instanton size \rho=0.33 fm, and the average inter-instanton distance
R=1 fm we obtain the dynamical light quark mass to be M = 365 MeV and the
instanton media contribution to the heavy quark mass \Delta M=70 MeV. These
factors define the coupling between heavy-light and heavy-heavy quarks induced
by the QCD vacuum instantons. We consider first the instanton effects on the
heavy-heavy quarks potential, including its spin-dependent part. We also
discuss those effects on the masses of the charmonia and their hyperfine mass
splittings. At the second part we discuss the interaction between a heavy and
light quarks generated by instantons and it's effects.
|
Dynamical histories of planetary systems, as well as atmospheric evolution of
highly irradiated planets, can be studied by characterizing the
ultra-short-period planet population, which the TESS mission is particularly
well suited to discover. Here, we report on the follow-up of a transit signal
detected in the TESS sector 19 photometric time series of the M3.0 V star
TOI-1685 (2MASS J04342248+4302148). We confirm the planetary nature of the
transit signal, which has a period of P_b=0.6691403+0.0000023-0.0000021 d,
using precise radial velocity measurements taken with the CARMENES
spectrograph. From the joint photometry and radial velocity analysis, we
estimate the following parameters for TOI-1685 b: a mass of M_b=3.78+/-0.63
M_Earth, a radius of R_b=1.70+/-0.07 R_Earth, which together result in a bulk
density of rho_b=4.21+0.95-0.82 g/cm3, and an equilibrium temperature of
Teq_b=1069+/-16 K. TOI-1685 b is the least dense ultra-short period planet
around an M dwarf known to date. TOI-1685 b is also one of the hottest
transiting Earth-size planets with accurate dynamical mass measurements, which
makes it a particularly attractive target for thermal emission spectroscopy.
Additionally, we report a further non-transiting planet candidate in the
system, TOI-1685[c], with an orbital period of P_[c]=9.02+0.10-0.12 d.
|
We study the gerbal representations of a finite group $G$ or, equivalently,
module categories over Ostrik's category $Vec_G^\alpha$ for a 3-cocycle
$\alpha$. We adapt Bartlett's string diagram formalism to this situation to
prove that the categorical character of a gerbal representation is a module
over the twisted Drinfeld double $D^\alpha(G)$. We interpret this twisted
Drinfeld double in terms of the inertia groupoid of a categorical group.
|
In this paper we characterize the Gorenstein $t$-spread Veronese algebras.
|
We summarize here recent results from the STAR collaboration focusing on
processes involving large momentum transfers. Measurements of angular
correlations of di-hadrons are explored in both the pseudorapidity (eta) and
azimuthal (phi) projections. In central Au+Au, an elongated structure is found
in the eta projection which persists up to the highest measured pT. After
quantifying the particle yield in this structure and subtracting it from the
near-side yield, we observe that the remainder exhibits a behavior strikingly
similar to that of the near-side yield in d+Au. For heavy flavor production,
using electron-hadron correlations in p+p collisions, we obtain an estimate of
the b-quark contribution to the non-photonic electrons in the pT region 3-6
GeV/c, and find it consistent with FONLL calculations. Together with the
observed suppression of non-photonic electrons in Au+Au, this strongly suggests
suppression of b-quark production in Au+Au collisions. We discuss results on
the mid-rapidity Upsilon cross-section in p+p collisions. Finally, we present a
proof-of-principle measurement of photon-hadron correlations in p+p collisions,
paving the way for the tomographic study of the matter produced in central
Au+Au via gamma-jet measurements.
|
Longitudinal confinement of dark solitons in quasi-one-dimensional
Bose-Einstein condensates leads to sound emission and reabsorption. We perform
quantitative studies of the dynamics of a soliton oscillating in a tight dimple
trap, embedded in a weaker harmonic trap. The dimple depth provides a sensitive
handle to control the soliton-sound interaction. In the limit of no
reabsorption, the power radiated is found to be proportional to the soliton
acceleration squared. An experiment is proposed to detect sound emission as a
change in amplitude and frequency of soliton oscillations.
|
We consider the dynamics of a single shock in a partially asymmetric simple
exclusion process (PASEP) on a finite lattice with open boundaries in the
sublattice-parallel updating scheme. We then construct the steady state of the
system by considering a linear superposition of these shocks. It is shown that
this steady state can also be written in terms of a product of four non-
commuting matrices. One of the main results obtained here is that these
matrices have exactly the same generic structure as the matrices first
introduced in Jafarpour and Masharian (2009 Phys. Rev. E 79 051124) indicating
that the steady state of a one-dimensional driven-diffusive system can be
written as a linear superposition of product shock measures. It is now easy to
explain the two-dimensional matrix representation of the PASEP with parallel
dynamics introduced in Essler and Rittenberg (1996 J. Phys. A: Math. Gen. 29
3375) and Honecker and Peschel (1997 J. Stat. Phys. 88 319).
|
We present spectro-polarimetric observations of Inter-Network magnetic fields
at the solar disk center. A Fabry-Perot spectrometer was used to scan the two
Fe I lines at 6301.5 A and 6302.5 A. High spatial resolution (0.5")
magnetograms were obtained after speckle reconstruction. The patches with
magnetic fields above noise cover approximately 45% of the observed area. Such
large coverage renders a mean unsigned magnetic flux density of some 20 G (or
20 Mx/cm^2), which exceeds all previous measurements. Magnetic signals occur
predominantly in intergranular spaces. The systematic difference between the
flux densities measured in the two iron lines leads to the conclusion that,
typically, we detect structures with intrinsic field strengths larger than 1kG
occupying only 2% of the surface.
|
We extend existing results that characterize isometries on the Tsirelson-type
spaces $T\big[\frac{1}{n}, \mathcal{S}_1\big]$ ($n\in \mathbb{N}, n\geq 2$) to
the class $T[\theta, \mathcal{S}_{\alpha}]$ ($\theta \in \big(0,
\frac{1}{2}\big]$, $1\leqslant \alpha < \omega_1$), where
$\mathcal{S}_{\alpha}$ denote the Schreier families of order $\alpha$.
We prove that every isometry on $T[\theta, \mathcal{S}_1]$ ($\theta \in
\big(0, \frac{1}{2}\big]$) is determined by a permutation of the first $\lceil
{\theta}^{-1} \rceil$ elements of the canonical unit basis followed by a
possible sign-change of the corresponding coordinates together with a
sign-change of the remaining coordinates. Moreover, we show that for the spaces
$T[\theta, \mathcal{S}_{\alpha}]$ ($\theta \in \big(0, \frac{1}{2}\big]$,
$2\leqslant \alpha < \omega_1$) the isometries exhibit a more rigid character,
namely, they are all implemented by a sign-change operation of the vector
coordinates.
|
We design a randomised parallel version of Adaboost based on previous studies
on parallel coordinate descent. The algorithm uses the fact that the logarithm
of the exponential loss is a function with coordinate-wise Lipschitz continuous
gradient, in order to define the step lengths. We provide the proof of
convergence for this randomised Adaboost algorithm and a theoretical
parallelisation speedup factor. We finally provide numerical examples on
learning problems of various sizes that show that the algorithm is competitive
with concurrent approaches, especially for large scale problems.
|
This work explores the large-scale multi-agent communication mechanism under
a multi-agent reinforcement learning (MARL) setting. We summarize the general
categories of topology for communication structures in MARL literature, which
are often manually specified. Then we propose a novel framework termed as
Learning Structured Communication (LSC) by using a more flexible and efficient
communication topology. Our framework allows for adaptive agent grouping to
form different hierarchical formations over episodes, which is generated by an
auxiliary task combined with a hierarchical routing protocol. Given each formed
topology, a hierarchical graph neural network is learned to enable effective
message information generation and propagation among inter- and intra-group
communications. In contrast to existing communication mechanisms, our method
has an explicit while learnable design for hierarchical communication.
Experiments on challenging tasks show the proposed LSC enjoys high
communication efficiency, scalability, and global cooperation capability.
|
The exotic decay modes of non-Standard Model Higgses can serve as powerful
search channels to explore the parameter space of extended Higgs sectors. In
this Snowmass contribution, we illustrate this using the Two-Higgs Doublet
Model (2HDM) as an example. We first review the current experimental
constraints on the parameter space of a Type-II 2HDM arising from existing
searches for the exotic Higgs decay mode $A/H\rightarrow HZ/AZ$. We then
present the sensitivity of future colliders to discover addition Higgs bosons
using the exotic decay channels $A\rightarrow HZ$, $A\rightarrow H^\pm W^\mp$
and $H^\pm\rightarrow H W^\pm$. We find that a 100 TeV collider can probe
almost the entire region of the Type-II 2HDM parameter space that survives
current theoretical and experimental constraints and would therefore be an
ideal machine to search for heavier Higgses in hierarchical scalar sectors.
|
In this work, we present the analytical solution of the effective mass Pauli
equation, with Rashba and linear Dresselhaus interactions, for an electron gas
moving through a semiconductor quantum dot under a longitudinal electric field,
which is defined along the $x$-direction. We study the relative influence of
the Rashba and Dresselhaus terms on the spin-Hall effect for the first
propagating and edge channels, by analyzing the mixing between spin-up and
-down states and the zero-field spin splitting along the transverse directions.
When the spin rotation depends only on the $y$-coordinate, the spin orientation
and the spin density vary along this transverse coordinate and, in this case,
we show that the spin-Hall effect is only due to the Dresselhaus term, for
depolarized electrons. On the other hand, if the spin rotation depends on the
$z$-coordinate, the spin-Hall effect is provoked only by the Rashba
interaction.
|
In this paper we consider the set of all bounded subsets of totally ordered
Dedekind complete Riesz spaces, equipped with the order topology. We show the
existence of bounded linear functions on this set, that are invariant under
group actions of the symmetric group of it.
|
A cylindrical model for the dark matter halo of disk galaxies is developed.
At the center of the cylinder, in the plane perpendicular to the long axis, the
rotation curve is constant for distances much less than the cylinder length and
Keplerian at much greater distances. The rotation curve is equivalent to the
spherical truncated flat (TF) profile, a model derived empirically from the
radial velocity dispersion of the Milky Way dark halo. It is shown that an
isothermal, self-gravitating cylinder of length 89 kpc can account for the
observed radial velocity dispersion of the Milky Way dark halo with less mass
than the NFW profile. Moreover, a cylindrical model of the Milky Way dark halo
is consistent with free-streaming neutrinos of mass 1.1 eV.
|
We characterise the integrability of any co-CR quaternionic structure in
terms of the curvature and a generalized torsion of the connection. Also, we
apply this result to obtain, for example, the following. (1) New co-CR
quaternionic structures built on vector bundles over a quaternionic manifold M,
whose twistor spaces are holomorphic vector bundles over the twistor space Z of
M. Moreover, all the holomorphic vector bundles over Z, which are positive and
isotypic when restricted to the twistor lines, are obtained this way. (2) Under
generic dimensional conditions, any manifold endowed with an almost
f-quaternionic structure and a compatible torsion free connection is, locally,
a product of a hypercomplex manifold with some power of the space of imaginary
quaternions.
|
It is proposed a dimensional Lattice Boltzmann Method (LBM) of wide
application for simulating fluid flow and heat transfer problems. The proposed
LBM consists in the numerical solution of the discrete lattice Boltzmann
equation (LBE) using directly the variables in physical units, without the
necessity of employing any particular unit conversion system. This includes the
integration of LBE in the discrete physical domain using the spatial and time
intervals and all the involved quantities in physical units. The dimensional
LBM is proposed for both the single and multiple relaxation time schemes,
considering the BGK and MRT collision operators, respectively. Several simple
tests problems treating different physical phenomena such as one dimensional
heat diffusion with source term, two dimensional forced convection with
developed and developing flow in a channel under an oscillating and constant
heat flux, two-phase stationary bubble in a liquid phase and two-phase dynamic
layered Poiseuille flow, both under very high density and viscosity ratios, are
simulated. All the numerical solutions were compared with analytical solutions,
when available, or with finite difference solutions, otherwise, showing a very
good agreement. The proposed method was also compared with the traditional LBM
for the treated problems, showing the same accuracy. Besides the simulation of
the applied problems employing physical units directly, the proposed LBM
allowed the solution of transport phenomena for more severe operational
conditions. This includes the simulation of the two multiphase problems with
liquid/gas density and gas/liquid kinematic viscosity ratios of about 43300 and
470 respectively, employing the Allen-Canh phase field model. With base on the
obtained results it is estimated that the proposed method could enhance the LBM
use as simulation tool.
|
Subsets and Splits