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Localization for Yang-Mills Theory on the Fuzzy Sphere: We present a new model for Yang-Mills theory on the fuzzy sphere in which the
configuration space of gauge fields is given by a coadjoint orbit. In the
classical limit it reduces to ordinary Yang-Mills theory on the sphere. We find
all classical solutions of the gauge theory and use nonabelian localization
techniques to write the partition function entirely as a sum over local
contributions from critical points of the action, which are evaluated
explicitly. The partition function of ordinary Yang-Mills theory on the sphere
is recovered in the classical limit as a sum over instantons. We also apply
abelian localization techniques and the geometry of symmetric spaces to derive
an explicit combinatorial expression for the partition function, and compare
the two approaches. These extend the standard techniques for solving gauge
theory on the sphere to the fuzzy case in a rigorous framework. | hep |
Feebly coupled vector boson dark matter in effective theory: A model of dark matter (DM) that communicates with the Standard Model (SM)
exclusively through suppressed dimension five operator is discussed. The SM is
augmented with a symmetry $U(1)_X \otimes Z_2$, where $U(1)_X$ is gauged and
broken spontaneously by a very heavy decoupled scalar. The massive $U(1)_X$
vector boson ($X^\mu$) is stabilized being odd under unbroken $Z_2$ and
therefore may contribute as the DM component of the universe. Dark sector field
strength tensor $X^{\mu\nu}$ couples to the SM hypercharge tensor $B^{\mu\nu}$
via the presence of a heavier $Z_2$ odd real scalar $\Phi$, i.e. $1/\Lambda \;
X^{\mu\nu}B_{\mu\nu}\Phi$, with $\Lambda$ being a scale of new physics. The
freeze-in production of the vector boson dark matter feebly coupled to the SM
is advocated in this analysis. Limitations of the so-called UV freeze-in
mechanism that emerge when the maximum reheat temperature $T_\text{RH}$ drops
down close to the scale of DM mass are discussed. The parameter space of the
model consistent with the observed DM abundance is determined. The model easily
and naturally avoids both direct and indirect DM searches. Possibility for
detection at the Large Hadron Collider (LHC) is also considered. A Stueckelberg
formulation of the model is derived. | hep |
Reduction of One-loop Tensor Form-Factors to Scalar Integrals: A General
Scheme: A general method for reducing tensor form factors, that appear in one-loop
calculations in dimensional regularization, to scalar integrals is presented.
The method is an extension of the reduction scheme introduced by Passarino and
Veltman and is applicable in all regions of parameter space including those
where kinematic Gram determinant vanishes. New relations between the the form
factors that valid for vanishing Gram determinant play a key role in the
extended scheme. | hep |
Combined measurements of anomalous charged trilinear gauge-boson
couplings from diboson production in p-pbar collisions at sqrt(s)=1.96 TeV: We present measurements of the anomalous WWgamma and WWZ trilinear gauge
couplings from a combination of four diboson production and decay channels
using data collected by the D0 detector at the Fermilab Tevatron Collider.
These results represent the first high statistics combination of limits across
different diboson production processes at the Tevatron and use data
corresponding to an integrated luminosity of approximately 1 fb^-1. When
respecting SU(2)_L x U(1)_Y symmetry, we measure central values and 68% C.L.
allowed intervals of kappa_gamma=1.07^+0.16_-0.20, lambda =0.00^+0.05_-0.04 and
g_1^Z=1.05 +/- 0.06. We present the most stringent measurements to date for the
W boson magnetic dipole and electromagnetic quadrupole moments of
mu_W=2.02^+0.08_-0.09 (e/2M_W) and q_W=-1.00 +/- 0.09 (e/M^2_W), respectively. | hep |
Slow nucleation rates in Chain Inflation with QCD Axions or Monodromy: The previous proposal (by two of us) of chain inflation with the QCD axion is
shown to fail. The proposal involved a series of fast tunneling events, yet
here it is shown that tunneling is too slow. We calculate the bubble nucleation
rates for phase transitions in the thick wall limit, approximating the barrier
by a triangle. A similar problem arises in realization of chain inflation in
the string landscape that uses series of minima along the monodromy staircase
around the conifold point. The basic problem is that the minima of the
potential are too far apart to allow rapid enough tunneling in these two
models. We entertain the possibility of overcoming this problem by modifying
the gravity sector to a Brans-Dicke theory. However, one would need extremely
small values for the Brans-Dicke parameter. Many successful alternatives exist,
including other "axions" (with mass scales not set by QCD) or potentials with
comparable heights and widths that do not suffer from the problem of slow
tunneling and provide successful candidates for chain inflation. | hep |
Search for Lepton Flavor Violating tau Decays into Three Leptons: We search for lepton-flavor-violating tau decays into three leptons (electron
or muon) using 535 fb^{-1} of data collected with the Belle detector at the
KEKB asymmetric-energy e+e- collider. No evidence for these decays is observed
and we set 90% confidence level upper limits on the branching fractions between
2.0x10^{-8} and 4.1x10^{-8}. These results improve the best previously
published upper limits by factors from 4.9 to 7.0. | hep |
Catching p via s wave with indirect detection: For many dark matter models, the annihilation cross section to two-body final
states is difficult to probe with current experiments because the dominant
annihilation channel is velocity or helicity suppressed. The inclusion of gauge
boson radiation for three-body final states can lift the helicity suppression,
allowing a velocity-independent cross section to dominate the annihilation
process, and providing an avenue to constrain these models. Here we examine
experimental constraints on dark matter that annihilates to two leptons plus a
bremsstrahlung boson, $\bar{\ell}+\ell+\gamma/W/Z$. We consider experimental
constraints on photon final states from Fermi-LAT using both diffuse photon
data and data from dwarf spheroidal galaxies, and compare to the implied
constraints from 21 cm measurements. Diffuse photon line searches are generally
the strongest over the entire mass regime. We in particular highlight the model
in which dark matter annihilates to two neutrinos and a photon, and show that
these models are more strongly constrained through photon measurements than
through existing neutrino bounds. | hep |
Derivations and noncommutative differential calculus II: We characterize the derivation $d:A\to \Omega^1_{\der}(A)$ by a universal
property introducing a new class of bimodules. | hep |
Vacuum Energy from an Extra Dimension with UV/IR Connection: We propose a lower limit on the size of a single discrete gravitational extra
dimension in the context of an effective field theory for massive gravitons.
The limit arises in this setup from the requirement that the Casimir energy
density of quantum fields is in agreement with the observed dark energy density
of the universe. The Casimir energy densities can be exponentially suppressed
to an almost arbitrarily small value by the masses of heavy bulk fields,
thereby allowing a tiny size of the extra dimension. This suppression is only
restricted by the strong coupling scale of the theory, which is known to be
related to the compactification scale via an UV/IR connection for local
gravitational theory spaces. We thus obtain an upper limit on the
compactification scale of the discrete gravitational extra dimension in the
range 10^7 GeV...10^12 GeV, while the strong coupling scale is by a factor 10^2
larger than the compactification scale. We also comment on a possible
cancelation of the gravitational contribution to the quantum effective
potential. | hep |
Holographic RG flow dual to attractor flow in extremal black holes: We extend the discussion of the "Kerr/CFT correspondence" and its recent
developments to the more general gauge/gravity correspondence in the full
extremal black hole space-time of the bulk by using a technique of the
holographic renormalization group (RG) flow. It is conjectured that the
extremal black hole space-time is holographically dual to the chiral two
dimensional field theory. Our example is a typical four dimensional
Reissner-Nordstrom black hole, a system in which the M5-brane is wrapped on
four cycles of Calabi-Yau threefold. In five dimensional supergravity view
point this near horizon geometry is $AdS_3\times S^2$, and three dimensional
gravity coupled to moduli fields is effectively obtained after a dimensional
reduction on $S^2$. Constructing the Hamilton-Jacobi equation, we define the
holographic RG flow from the three dimensional gravity. The central charge of
the Virasoro algebra is calculable from the conformal anomaly at the point
where the beta function defined from gravity side becomes zero. In general, we
can also identify the c-function of the dual two dimensional field theory. We
show that these flow equations are completely equivalent to not only BPS but
also non-BPS attractor flow equations of the muduli fields. The attractor
mechanism by which the values of the moduli fields are fixed at the event
horizon of the extremal black hole can be understood equivalently to the fact
that the RG flows are fixed at the critical points in the dual field theory. | hep |
Neutrino oscillations as a novel probe for a minimal length: We suggest that the presence of a quantum gravity induced minimal length can
be explored using neutrino oscillation probabilities. Neutrinos seem ideally
suited for this investigation because they can propagate freely over large
distances and can therefore pile up minimal length effects beyond detectable
thresholds. We determine the modified survival probability in a scenario with a
minimal length and find deviations from the classical behaviour for high
energies. We find that for the currently available experimental statistics the
deviations from the standard oscillations do only allow for a bound of
$\ell^{-1}\gtrsim 10 \mathrm{GeV}$ from MINOS data. On the other hand,
oscillations of high-energy neutrinos emitted by galactic and extragalactic
sources are strongly suppressed, leading to a possible observation of quantum
gravity effects at neutrino telescopes such as IceCube and ANTARES. | hep |
Feasibility of the experimental study of $D_{s}^{\ast}$ ${\to}$
$φπ$ decay: The current knowledge on the $D_{s}^{\ast}$ meson are very limited. Besides
the dominant electromagnetic decays, the $D_{s}^{\ast}$ weak decays are legal
and offer the valuable opportunities to explore the wanted $D_{s}^{\ast}$
meson. In this paper, the $D_{s}^{\ast}$ ${\to}$ ${\phi}{\pi}$ decay was
studied with the factorization approach. It is found that the branching ratio
${\cal B}(D_{s}^{\ast}{\to}{\phi}{\pi})$ ${\sim}$ ${\cal O}(10^{-7})$, which
corresponds to several thousands of events at the $e^{+}e^{-}$ collider
experiments including STCF, SuperKEKB, CEPC and FCC-ee, and several millions of
events at the hadron collider experiments, such as LHCb@HL-LHC. It is feasible
to experimentally study the $D_{s}^{\ast}$ ${\to}$ ${\phi}{\pi}$ weak decay in
the future, even considering the identification efficiency. | hep |
The quark-antiquark spectrum from upside down: We argue that the spectra of quark-antiquark systems should better be studied
from higher radial excitations and, in particular, from configurations with
well-defined quantum numbers, rather than from ground states and lower radial
excitations, the most suitable system being charmonium. | hep |
The gluon/charm content of the eta' meson and instantons: Motivated by recent CLEO measurements of the B-->\eta' K decay, we evaluate
gluon/charm content of the eta' meson using the interacting instanton liquid
model of the QCD vacuum. Our result is very large due to the strong field of
small-size instantons. We show that it provides quantitative explanations of
the CLEO data on the B-->\eta' K decay rate (as well as inclusive process
B-->\eta' X), via a virtual Cabbibo-unsuppressed decay into \bar c c pair which
then becomes eta'. If so, a significant charm component should be present in
other hadrons also. In particular, we found a large contribution of the charmed
quark in the polarised deep-inelastic scattering on a proton. | hep |
Proton Decay in the Supersymmetric Grand Unified Models: In this article we review proton decay in the supersymmetric grand unified
models. | hep |
Massive spinning particle in any dimension. II. (Half-)integer spins: The general model of an arbitrary spin massive particle in any dimensional
space-time is derived on the basis of Kirillov - Kostant - Souriau approach.
Keywords: spinning particles, Poincar\'e group, orbit method, constrained
dynamics, geometric quantization. | hep |
Holography and the speed of sound at high temperatures: We show that in a general class of strongly interacting theories at high
temperatures the speed of sound approaches the conformal value c_s^2=1/3
universally from_below_. This class includes theories holographically dual to a
theory of gravity coupled to a single scalar field, representing the operator
of the scale anomaly. | hep |
Maximal Supersymmetry and B-Mode Targets: Extending the work of Ferrara and one of the authors, we present dynamical
cosmological models of $\alpha$-attractors with plateau potentials for
$3\alpha=1,2,3,4,5,6,7$. These models are motivated by geometric properties of
maximally supersymmetric theories: M-theory, superstring theory, and maximal $N
= 8$ supergravity. After a consistent truncation of maximal to minimal
supersymmetry in a seven-disk geometry, we perform a two-step procedure: 1) we
introduce a superpotential, which stabilizes the moduli of the seven-disk
geometry in a supersymmetric minimum, 2) we add a cosmological sector with a
nilpotent stabilizer, which breaks supersymmetry spontaneously and leads to a
desirable class of cosmological attractor models. These models with $n_s$
consistent with observational data, and with tensor-to-scalar ratio $r \approx
10^{-2}- 10^{-3}$, provide natural targets for future B-mode searches. We
relate the issue of stability of inflationary trajectories in these models to
tessellations of a hyperbolic geometry. | hep |
Dynamical Stability of Six-dimensional Warped Flux Compactification: We show the dynamical stability of a six-dimensional braneworld solution with
warped flux compactification recently found by the authors. We consider linear
perturbations around this background spacetime, assuming the axisymmetry in the
extra dimensions. The perturbations are expanded by scalar-, vector- and
tensor-type harmonics of the four-dimensional Minkoswki spacetime and we
analyze each type separately. It is found that there is no unstable mode in
each sector and that there are zero modes only in the tensor sector,
corresponding to the four-dimensional gravitons. We also obtain the first few
Kaluza-Klein modes in each sector. | hep |
Three point interaction of Dirac fermions with higher spin particles and
discrete symmetries: We constructed all possible kinematically allowed three-point interactions of
two massless Dirac spinors with massive higher-spin bosons. In any $D$
spacetime, the interactions have been constructed using the projections of the
massive higher spin representations of $Spin(D-1)$ over the massless complex
spinor representations of $Spin(D-2)\times Spin(D-2)$. Based on this analysis,
we have further classified the space of theories involving one massless Dirac
spinor and a single (or multiple) massive higher spins based on the discrete
symmetries: $C,\, R,$ and $ T$. We found that in any $D=2m+1/2m$, the
interacting theories of a single massive higher spin have a \enquote{$m$} mod
$2$ (or $D$ mod $4$) classification. | hep |
A Search of Low-Mass WIMPs with p-type Point Contact Germanium Detector
in the CDEX-1 Experiment: The CDEX-1 experiment conducted a search of low-mass (< 10 GeV/c2) Weakly
Interacting Massive Particles (WIMPs) dark matter at the China Jinping
Underground Laboratory using a p-type point-contact germanium detector with a
fiducial mass of 915 g at a physics analysis threshold of 475 eVee. We report
the hardware set-up, detector characterization, data acquisition and analysis
procedures of this experiment. No excess of unidentified events are observed
after subtraction of known background. Using 335.6 kg-days of data, exclusion
constraints on the WIMP-nucleon spin-independent and spin-dependent couplings
are derived. | hep |
Background to Higgs-boson searches from internal conversions of
off-shell photons associated with $Z/γ^*$-boson production at the LHC: This paper presents the studies of the background contribution to the $H
\rightarrow 4l$ searches originating from the processes of off-shell (virtual)
photon emissions and their conversions into lepton pairs accompanying the
production of $Z/ \gamma ^*$-bosons at the LHC. They extend the analyses of the
irreducible background presented in the ATLAS and CMS Higgs papers by taking
into account the emissions of off-shell photons by parton showers. Including
these effects does not change significantly the Higgs-searches background
level, provided that the transverse momentum of each of the final-state leptons
is restricted to the range of $p_{T, l} > 7$ GeV. In the kinematical region
extended towards lower lepton transverse momenta the parton-shower contribution
becomes important. A measurement method for pinning down the parton-shower
effects is proposed. | hep |
On Bound-State beta^- Decay Rate of the Free Neutron: We calculate the bound-state beta^- decay rate of the free neutron. We show
that hydrogen in the final state of the decay is produced with a probability of
about 99% in the hyperfine state with zero orbital l = 0 and atomic angular
momentum F = 0. | hep |
Where does curvaton reside? Differences between bulk and brane frames: Some classes of inflationary models naturally introduce two distinct
metrics/frames, and their equivalence in terms of observables has often been
put in question. D-brane inflation proposes candidates for an inflaton embedded
in the string theory and possesses descriptions on the brane and bulk
metrics/frames, which are connected by a conformal/disformal transformation
that depends on the inflaton and its derivatives. It has been shown that
curvature perturbations generated by the inflaton are identical in both frames,
meaning that observables such as the spectrum of cosmic microwave background
(CMB) anisotropies are independent of whether matter fields---including those
in the standard model of particle physics---minimally couple to the brane or
the bulk metric/frame. This is true despite the fact that the observables are
eventually measured by the matter fields and that the total action including
the matter fields is different in the two cases. In contrast, in curvaton
scenarios, the observables depend on the frame to which the curvaton minimally
couples. Among all inflationary scenarios, we focus on two models motivated by
the KKLMMT fine-tuning problem: a slow-roll inflation with an inflection-point
potential and a model of a rapidly rolling inflaton that conformally couples to
gravity. In the first model, the difference between the frames in which the
curvaton resides is encoded in the spectral index of the curvature
perturbations, depicting the nature of the frame transformation. In the second
model, the curvaton on the brane induces a spectral index significantly
different from that in the bulk and is even falsified by the observations. This
work thus demonstrates that two frames connected by a conformal/disformal
transformation lead to different physical observables such as CMB anisotropies
in curvaton models. | hep |
In Memoriam Nikolai Uraltsev : Uraltsev's and other Sum Rules, Theory
and Phenomenology of $D^{**}$'s: We first discuss Uraltsev's and other sum rules constraining the $B \to
D^{**}(L=1)$ weak transitions in the infinite mass limit, and compare them with
dynamical approaches in the same limit. After recalling these well established
facts, we discuss how to apply infinite mass limit to the physical situation.
We provide predictions concerning semi-leptonic decays and non-leptonic ones,
based on quark models. We then present in more detail the dynamical approaches:
the relativistic quark model \`a la Bakamjian-Thomas and lattice QCD. We
summarise lattice QCD results in the infinite mass limit and compare them to
the quark model predictions. We then present preliminary lattice QCD results
with finite $b$ and $c$ quark masses. A systematic comparison between theory
and experiment is performed. We show that some large discrepancies exist
between different experiments. Altogether the predictions at infinite mass are
in fair agreement with experiment for non-leptonic decays contrary to what
happens for semileptonic decays. We conclude by considering the prospects to
clarify both the experimental situation, the theoretical one and the comparison
between both. | hep |
Vortex waistlines and long range fluctuations: We examine the manner in which a linear potential results from fluctuations
due to vortices linked with the Wilson loop. Our discussion is based on exact
relations and inequalities between the Wilson loop and the vortex and electric
flux order parameters. We show that, contrary to the customary naive picture,
only vortex fluctuations of thickness of the order of the spatial linear size
of the loop are capable of producing a strictly linear potential. An effective
theory of these long range fluctuations emerges naturally in the form of a
strongly coupled Z(N) lattice gauge theory. We also point out that dynamical
fermions introduced in this medium undergo chiral symmetry breaking. | hep |
The bound state corrections to the semileptonic decays of the heavy
baryons: We present an investigation of the lepton energy distributions in the
inclusive semileptonic weak decays of heavy baryons performed within a
relativistic quark model formulated on the light front (LF). Using the
heavy-quark LF distribution functions related to the equal time momentum wave
functions taken from the Kalman--Tran--D'Souza model we compute the electron
energy spectra and the total semileptonic widths of the Lambda_Q and Xi_Q
(Q=c,b) baryons and confront the results with existing data. | hep |
Color-neutral heavy particle production in nucleus-nucleus collisions in
the quasi-classical approximation: We use a diagrammatic approach to study color-neutral heavy particle
production in nucleus-nucleus collisions in a quasi-classical approximation
without small-$x$ evolution. In order to treat the two nuclei symmetrically, we
use the Coulomb gauge which gives the appropriate light cone gauge for each
nucleus. The resulting cross section is factorized into a product of two
Weizs\"{a}cker-Williams gluon distributions of the two nuclei when the
transverse momentum of the produced scalar particle is around the saturation
momentum. We confirm our results in covariant gauge where the transverse
momentum broadening of hard gluons can be described as a diffusion process. The
transverse momentum factorization manifests itself in light cone gauge but not
so clearly in covariant gauge. | hep |
The spatial string tension and dimensional reduction in QCD: The spatial string tension for 3+1 dimensional QCD at finite temperature is
measured. The gauge configurations we re generated with two light and one
heavier strange quark on lattices of size $16^3 4$ and $24^3 6$. This spatial
string tension is compared with the string tension of the 3 dimensional pure
gauge theory together with the temperature dependent 2-loop running coupling.
Further comparison is made with predictions from dimensionally reduced
effective theories. | hep |
The Color Glass Condensate and Glasma: These two lectures concern the Color Glass Condensate and the Glasma. These
are forms of matter which might be studied in high energy hadronic collisions.
The Color Glass Condensate is high energy density gluonic matter. It
constitutes the part of a hadron wavefunction important for high energy
processes. The Glasma is matter produced from the collision of two high energy
hadrons. Both types of matter are associated with coherent fields. The Color
Glass Condensate is static and related to a hadron wavefunction where the
glasma is transient and evolves quickly after a collision. I present the
properties of such matter, and some aspects of what is known of their
properties. | hep |
Dynamical Gap and Cuprate-like Physics from Holography: We study the properties of fermion correlators in a boundary theory dual to
the Reissner-Nordstr\"om AdS_{d+1} background in the presence of a bulk dipole
(Pauli) interaction term with strength p. We show that by simply changing the
value of the parameter p we can tune continuously from a Fermi liquid (small
p), to a marginal Fermi liquid behavior at a critical value of p, to a generic
non-Fermi liquid at intermediate values of p, and finally to a Mott insulator
at large values of the bulk Pauli coupling. As all of these phases are seen in
the cuprate phase diagram, the holographic model we study has the key elements
of the strong coupling physics typified by Mott systems. In addition, we extend
our analysis to finite temperature and show that the Mott gap closes. Of
particular interest is that it closes when the ratio of the gap to the critical
temperature is of the order of ten. This behavior is very much similar to that
observed in the classic Mott insulator VO_2. We then analyze the
non-analyticities of the boundary theory fermion correlators for generic values
of frequency and momentum by calculating the quasi-normal modes of the bulk
fermions. Not surprisingly, we find no evidence for the dipole interaction
inducing an instability in the boundary theory. Finally, we briefly consider
the introduction of superconducting condensates, and find that in that case,
the fermion gap is driven by scalar-fermion couplings rather than by the Pauli
coupling. | hep |
ABJM at finite $N$ via 4d supergravity: We apply the conjecture of arXiv:2111.06903 for gravitational building blocks
to the effective supergravity description of M-theory on S$^7/\mathbb{Z}_k$.
Utilizing known localization results for the holographically dual ABJM theory,
we determine a complete tower of higher derivative corrections to the AdS$_4$
supergravity and a further set of quantum corrections. This uniquely fixes the
gravitational block, leading to holographic predictions for a number of exact
ABJM observables, excluding only constant and non-perturbative corrections in
the gauge group rank $N$. The predicted S$^3$ partition function is an Airy
function that reproduces previous results and generalizes them to include
arbitrary squashing and mass deformations/R-charge assignments. The
topologically twisted and superconformal indices are instead products of two
different Airy functions, in agreement with direct numeric calculations in the
unrefined limit of the former object. The general fixed-point formula for an
arbitrary supersymmetric background is similarly given as a product of Airy
functions. | hep |
Tetra-quark mesons with exotic quantum numbers: Tetra-quark mesons with exotic quantum numbers, their production rates and
decay properties are studied, because they are useful to establish existence of
tetra-quark mesons. | hep |
Light-front potential for heavy quarkonia constrained by the holographic
soft-wall model: We derive a light-front Schrodinger-type equation of motion for the
quark-antiquark wave function of heavy quarkonia imposing constraints from the
holographic soft-wall model. | hep |
Supersymmetric Dark Matter - a Review: I address the question of whether supersymmetry provides a viable candidate
for the dark matter in the Universe. I review the properties of the lightest
neutralino as a candidate for solving the dark matter problem. I discuss the
neutralino's phenomenological and cosmological properties, and constraints from
present and future experiments. In the minimal supersymmetric model, the
neutralino mass has been experimentally excluded below some $20$ GeV, and is
not expected to be significantly larger than about $150$ GeV. I identify a
gaugino-like neutralino as the most natural dark matter candidate for a
plausible range of parameters. The requirement that the lightest neutralino be
the dominant matter component in the flat Universe provides non-trivial
restrictions on other parameters of the model, in particular on the masses of
the sfermions. Next, I study the consequences of adopting further grand
unification assumptions. In both scenarios I find sfermion masses most likely
beyond the reach of LEP 200 and the Tevatron but well within the discovery
potential of the SSC and the LHC. I also comment on the effects of relaxing
grand unification assumptions. Finally, I briefly outline prospects for the
neutralino dark matter searches. | hep |
First-Order Gauge Invariant Generalization of the Quantum Rigid Rotor: A first-order gauge invariant formulation for the two-dimensional quantum
rigid rotor is long known in the theoretical physics community as an isolated
peculiar model. Parallel to that fact, the longstanding constraints
abelianization problem, aiming at the conversion from second to first class
systems for quantization purposes, has been approached a number of times in the
literature with a handful of different forms and techniques and still continues
to be a source of lively and interesting discussions. Connecting these two
points, we develop a new systematic method for converting second class systems
to first class ones, valid for a class of systems encompassing the quantum
rigid rotor as a special case. In particular the gauge invariance of the
quantum rigid rotor is fully clarified and generalized in the context of
arbitrary translations along the radial momentum direction. Our method differs
substantially from previous ones as it does not rely neither on the
introduction of new auxiliary variables nor on the a priori interpretation of
the second class constraints as coming from a gauge-fixing process. | hep |
Phenomenological Analyses on Hadronic Cross-Sections at High and
Asymptotic Energies: Quantum Chromodynamics constitutes the quantum field theory of the strong
interaction. Despite the success of this theory in the description of several
hadronic processes, the elastic scattering is still a theoretical challenge.
This process is characterized by a small transferred momentum and the
perturbative techniques are not applicable. Although nonperturbative results
have been obtained in recent years, we still do not have a full description
within QCD of the quantities related to the elastic scattering, for example,
$\sigma_{tot}$, the $\rho$ parameter and $\sigma_{el}$. In this thesis, the
main interest is in the energy dependence of the ratio
$X=\sigma_{el}/\sigma_{tot}$, $\sigma_{tot}$ and $\rho$. These topics are
divided into three different studies. In the first topic, we develop an
empirical analysis on the ratio $X$. By means of parameterizations with a small
number of free parameters, we have obtained good descriptions of the data on
$pp$ and $\bar{p}p$ scattering. We conclude that the asymptotic black-disk
scenario is not a unique solution and the results favour a grey-disk scenario.
In the second topic, we study the rise of $\sigma_{tot}$ with the energy
through parameterizations based on the Regge-Gribov formalism and we consider
two options for the leading term: a log-square and a log-raised-to-$\gamma$,
with $\gamma$ a free fit parameter. We discuss two analytic methods to connect
the real and imaginary parts of the amplitude: Derivative Dispersion Relations
(DDR) and Asymptotic Uniqueness, which lead to different parameterizations for
$\sigma_{tot}$ and $\rho$. The results favour the DDR method in both formal and
practical contexts. In the third topic, two sub-leading terms for
$\sigma_{tot}$, obtained in a nonperturbative QCD approach, are considered in
fits to $pp$ and $\bar{p}p$ data and also in fits to data from meson-baryon and
other baryon-baryon scattering. | hep |
Supersymmetry breaking in ISS coupled to gravity: We analyse the breakdown of supersymmetry in an ISS model in the presence of
gravity, under the requirement that the cosmological constant vanishes
dynamically. The gravitational backreaction is calculated in the metastable
minimum and, in conjuction with the condition V=0, this is shown to generate
non-zero F-terms for the squarks. Once the squarks are coupled to the messenger
sector, a gauge mediation scheme is realised and it leads to a distinctive soft
spectrum, with a two order of magnitude split between the gaugino and the soft
scalar masses. | hep |
Forward production of $Υ$ mesons in $pp$ collisions at
$\sqrt{s}=7$ and 8TeV: The production of $\Upsilon$ mesons in $pp$ collisions at $\sqrt=7$ and
$8\,\mathrm{TeV}$ is studied with the LHCb detector using data samples
corresponding to an integrated luminosity of $1\,\mathrm{fb}^{-1}$ and
$2\,\mathrm{fb}^{-1}$ respectively. The production cross-sections and ratios of
cross-sections are measured as functions of the meson transverse momentum $p_T$
and rapidity $y$, for $p_T<30\,\mathrm{GeV}/c$} and $2.0<y<4.5$. | hep |
QCD monopoles, abelian projections and gauge invariance: It is shown that the creation of a monopole is a gauge invariant statement,
based on topology. Creating a monopole is independent on the abelian projection
in which it is created. This is fundamental in defining an order parameter for
detecting dual superconductivity of the QCD vacuum. | hep |
Light Higgses and Dark Matter at Bottom and Charm Factories: Neither Dark Matter nor scalar particles in the Higgs sector are ruled out at
energies accessible to bottom and charm factories. In Dark Matter searches, the
error on the mass of Dark Matter is $\sim 4$ GeV in the best LHC studies. For
light Dark Matter this could represent a 100% (or more) error. In Higgs
searches, the presence of a light singlet Higgs can make the LHC Higgs search
difficult, if not impossible. If Dark Matter or a Higgs scalar is light, it
will {\it require} a low-energy machine to precisely determine the couplings.
We review the models, modes of discovery and rate expectations for these new
particle searches at bottom and charm factories. We also discuss the options
for new runs at bottom and charm factories relevant for these searches. | hep |
Some aspects of final states and QCD evolution equations: In order to study such effects like parton saturation in final states at the
LHC one of the approaches is to combine physics of the BK and the CCFM
evolution equations. We report on recently obtained resummed form of the BK
equation and nonlinear extension of the CCFM equation - the KGBJS equation. | hep |
Scattering of shock waves in QCD: The cross section of heavy-ion collisions is represented as a double
functional integral with the saddle point being the classical solution of the
Yang-Mills equations with boundary conditions/sources in the form of two shock
waves corresponding to the two colliding ions. I develop the expansion of this
classical solution in powers of the commutator of the Wilson lines describing
the colliding particles and calculate the first two terms of the expansion. | hep |
Comments on lump solutions in SFT: We analyze a recently proposed scheme to construct analytic lump solutions in
open SFT. We argue that in order for the scheme to be operative and guarantee
background independence it must be implemented in the same 2D conformal field
theory in which SFT is formulated. We outline and discuss two different
possible approaches. Next we reconsider an older proposal for analytic lump
solutions and implement a few improvements. In the course of the analysis we
formulate a distinction between regular and singular gauge transformations and
advocate the necessity of defining a topology in the space of string fields. | hep |
Very low energy matching of effective meson theories with QCD: A simple matching procedure is proposed to extract constraints on effective
meson theories. In this way, a QCD prediction for the pion decay constant is
found, F(pi)=2 m(pi)/pi, i.e. approximately 90MeV. The same procedure also
determines other mesonic observables, like the decay width of the sigma meson
to two photons. Finally, some information which can be gained about the
hadronic light-by-light contributions to the muon anomalous moment are briefly
commented. | hep |
Matrix model approach to minimal Liouville gravity revisited: Using the connection with the Frobenius manifold structure, we study the
matrix model description of minimal Liouville gravity (MLG) based on the
Douglas string equation. Our goal is to find an exact discrete formulation of
the (q,p) MLG model that intrinsically contains information about the conformal
selection rules. We discuss how to modify the Frobenius manifold structure
appropriately for this purposes. We propose a modification of the construction
for Lee-Yang series involving the $A_{p-1}$ algebra instead of the previously
used $A_1$ algebra. With the new prescription, we calculate correlators on the
sphere up to four points and find full agreement with the continuous approach
without using resonance transformations. | hep |
A Pseudoscalar Resonance That Could Resemble the Higgs: As described previously, in SU(5) gauge theory with massless left-handed $
{\bf 5 \oplus 15 \oplus 40 \oplus 45^*}$ fermions \{QUD\}, an S-Matrix is
produced by infra-red anomaly dynamics that might provide an extraordinarily
economic origin and unification for the Standard Model. All particles are
bound-states, with dynamically generated masses, and there is no Higgs sector.
In this paper, the radically different dynamical role played by the top quark
is elaborated. It does not reproduce Standard Model "$ t\bar{t} $" events but,
instead, these events are reproduced by the multiple vector boson decays of the
$\eta_6$ - the remnant pseudoscalar resonance left by color sextet electroweak
symmetry breaking. Evidence that the $\eta_6$ appears in LHC and Tevatron Z
pair cross-sections is discussed. A second pseudoscalar resonance, the
$\eta_3$, contains a $t\bar{t}$ pair and mixes with the $\eta_6$ via the
pomeron. The mixing should give the $\eta_3$ a mass between the triplet and
sextet scales. It could also have a decay mode pattern that is more consistent
with LHC and Tevatron results than the (mass spectrum determined) pattern of
the Standard Model Higgs boson that many hope has been discovered.
Unfortunately, at present, there is no possibility to calculate explicit
cross-sections. | hep |
Towards M2-brane Theories for Generic Toric Singularities: We construct several examples of (2+1) dimensional N=2 supersymmetric
Chern-Simons theories, whose moduli space is given by non-compact toric
Calabi-Yau four-folds, which are not derivable from any (3+1) dimensional CFT.
One such example is the gauge theory associated with the cone over Q^{111}. For
several examples, we explicitly confirm the matter content, superpotential
interactions and RG flows suggested by crystal models. Our results provide
additional support to the idea that crystal models are relevant for describing
the structure of these CFTs. | hep |
Flavour data constraints on new physics and SuperIso: We discuss the implications of B_s -> mu+mu- and B -> K*mu+mu- decays in the
context of indirect searches for new physics, emphasising the new LHCb results.
In particular, we derive the consequences of the MFV hypothesis and discuss the
importance of the MFV predictions. The impact of the recent LHCb measurements
in the context of the MSSM will also be addressed, and the SuperIso program
will be briefly described. | hep |
Transverse Single-Spin Asymmetries of Midrapidity Direct Photons and
Neutral Mesons at PHENIX: Results are presented for the transverse single-spin asymmetries of direct
photons, neutral pions, and eta mesons for $|\eta|<0.35$ from $p^\uparrow + p$
collisions with $\sqrt{s} = 200$ GeV at PHENIX. As hadrons, $\pi^0$ and $\eta$
mesons are sensitive to both initial- and final-state effects and at
midrapidity probe the dynamics of gluons along with a mix of quark flavors.
Because direct photon production does not include hadronization, the direct
photon TSSA is only sensitive to initial-state effects and at midrapidity
provides a clean probe of the gluon dynamics in transversely polarized protons.
All three of these results will help constrain the collinear twist-3 trigluon
correlation function as well as the gluon Sivers function, improving our
knowledge of spin-dependent gluon dynamics in QCD. | hep |
Anisotropic pressure induced by finite-size effects in SU(3) Yang-Mills
theory: We study the pressure anisotropy in anisotropic finite-size systems in SU(3)
Yang-Mills theory at nonzero temperature. Lattice simulations are performed on
lattices with anisotropic spatial volumes with periodic boundary conditions.
The energy-momentum tensor defined through the gradient flow is used for the
analysis of the stress tensor on the lattice. We find that a clear finite-size
effect in the pressure anisotropy is observed only at a significantly shorter
spatial extent compared with the free scalar theory, even when accounting for a
rather large mass in the latter. | hep |
Searches for magnetic monopoles and others stable massive particles: The Standard Model (SM) of the microcosm provides an excellent description of
the phenomena of the microcosm, with the triumph of the discovery of the Higgs
boson. There are many reasons, however, to believe that the SM is incomplete
and represents a valid theory at relatively low energies only. Of particular
interest are the models based on complete symmetries, such as those attempting
a true unification between leptons and quarks in terms of a single symmetry
group (Grand Unified Theories, GUTs) and those attempting unification between
fermions and bosons, such as the supersymmetry. This chapter is devoted to the
description of stable and massive particles not predicted within the SM, their
energy loss mechanisms and their searches in the cosmic radiation. The
stability of these particles means that if they were produced at any time in
the thermal history of the Universe, they would still be present as relic
particles. Examples of stable massive particles discussed in this chapter
include magnetic monopoles, strange quark matter and supersymmetric particles.
In particular, we focus on the status of searches for magnetic monopoles (also
inducing proton-decay processes), nuclearites and Q-balls in neutrino
telescopes. | hep |
On $d=4$ Yang-Mills instantons in a spherically symmetric background: We present arguments for the existence of self-dual Yang-Mills instantons for
several spherically symmetric backgrounds with Euclidean signature. The
time-independent Yang-Mills field has finite action and a vanishing energy
momentum tensor and does not disturb the geometry. We conjecture the existence
of similar solutions for any nonextremal SO(3)-spherically symmetric
background. | hep |
Search for axion-like dark matter with ferromagnets: Existence of dark matter indicates the presence of unknown fundamental laws
of nature. Ultralight axion-like particles are well-motivated dark matter
candidates, emerging naturally from theories of physics at ultrahigh energies.
We report the results of a direct search for the electromagnetic interaction of
axion-like dark matter in the mass range that spans three decades from 12 peV
to 12 neV. The detection scheme is based on a modification of Maxwell's
equations in the presence of axion-like dark matter, which mixes with a static
magnetic field to produce an oscillating magnetic field. The experiment makes
use of toroidal magnets with iron-nickel alloy ferromagnetic powder cores,
which enhance the static magnetic field by a factor of 24. Using SQUIDs, we
achieve a magnetic sensitivity of 150 $\text{aT}/\sqrt{\text{Hz}}$, at the
level of the most sensitive magnetic field measurements demonstrated with any
broadband sensor. We recorded 41 hours of data and improved the best limits on
the magnitude of the axion-like dark matter electromagnetic coupling constant
over part of our mass range, at 20 peV reaching $4.0 \times 10^{-11}
\text{GeV}^{-1}$ (95\% confidence level). Our measurements are starting to
explore the coupling strengths and masses of axion-like particles where mixing
with photons could explain the anomalous transparency of the universe to TeV
gamma-rays. | hep |
Electron and photon energy calibration with the ATLAS detector using
2015-2016 LHC proton-proton collision data: This paper presents the electron and photon energy calibration obtained with
the ATLAS detector using about 36 fb$^{-1}$ of LHC proton-proton collision data
recorded at $\sqrt{s}=13$ TeV in 2015 and 2016. The different calibration steps
applied to the data and the optimization of the reconstruction of electron and
photon energies are discussed. The absolute energy scale is set using a large
sample of $Z$ boson decays into electron--positron pairs. The systematic
uncertainty in the energy scale calibration varies between 0.03% to 0.2% in
most of the detector acceptance for electrons with transverse momentum close to
45 GeV. For electrons with transverse momentum of 10 GeV the typical
uncertainty is 0.3% to 0.8% and it varies between 0.25% and 1% for photons with
transverse momentum around 60 GeV. Validations of the energy calibration with
$J/\psi \rightarrow e^+e^-$ decays and radiative $Z$ boson decays are also
presented. | hep |
Twofold Transition in PT-Symmetric Coupled Oscillators: The inspiration for this theoretical paper comes from recent experiments on a
PT-symmetric system of two coupled optical whispering galleries (optical
resonators). The optical system can be modeled as a pair of coupled linear
oscillators, one with gain and the other with loss. If the coupled oscillators
have a balanced loss and gain, the system is described by a Hamiltonian and the
energy is conserved. This theoretical model exhibits two PT transitions
depending on the size of the coupling parameter \epsilon. For small \epsilon
the PT symmetry is broken and the system is not in equilibrium, but when
\epsilon becomes sufficiently large, the system undergoes a transition to an
equilibrium phase in which the PT symmetry is unbroken. For very large \epsilon
the system undergoes a second transition and is no longer in equilibrium. The
classical and the quantized versions of the system exhibit transitions at
exactly the same values of \epsilon. | hep |
Cosmological Inflation and the Quantum Measurement Problem: According to cosmological inflation, the inhomogeneities in our universe are
of quantum mechanical origin. This scenario is phenomenologically very
appealing as it solves the puzzles of the standard hot big bang model and
naturally explains why the spectrum of cosmological perturbations is almost
scale invariant. It is also an ideal playground to discuss deep questions among
which is the quantum measurement problem in a cosmological context. Although
the large squeezing of the quantum state of the perturbations and the
phenomenon of decoherence explain many aspects of the quantum to classical
transition, it remains to understand how a specific outcome can be produced in
the early universe, in the absence of any observer. The Continuous Spontaneous
Localization (CSL) approach to quantum mechanics attempts to solve the quantum
measurement question in a general context. In this framework, the wavefunction
collapse is caused by adding new non linear and stochastic terms to the
Schroedinger equation. In this paper, we apply this theory to inflation, which
amounts to solving the CSL parametric oscillator case. We choose the
wavefunction collapse to occur on an eigenstate of the Mukhanov-Sasaki variable
and discuss the corresponding modified Schroedinger equation. Then, we compute
the power spectrum of the perturbations and show that it acquires a universal
shape with two branches, one which remains scale invariant and one with nS=4, a
spectral index in obvious contradiction with the Cosmic Microwave Background
(CMB) anisotropy observations. The requirement that the non-scale invariant
part be outside the observational window puts stringent constraints on the
parameter controlling the deviations from ordinary quantum mechanics...
(Abridged). | hep |
$ψ'$ Polarization due to Color-Octet Quarkonia Production: We calculated the polarization of \psi' due to gg \to Q\bar{Q}[^3P_J^(8)]g
\to \psi^\lambda color-octet quarkonia production. We find that at low
transverse momenta the \psi' is unpolarized due to the contributions
proportional to the L=S=0 and L=S=1 color-octet matrix elements. As p_\perp
increases, the \psi' mesons become 100% polarized, as predicted by
fragmentation calculations. Polarization due to lowest order color-singlet
production is also considered, which qualitatively has a similar shape to the
color-octet production. | hep |
Horizon as Critical Phenomenon: We show that renormalization group(RG) flow can be viewed as a gradual wave
function collapse, where a quantum state associated with the action of field
theory evolves toward a final state that describes an IR fixed point. The
process of collapse is described by the radial evolution in the dual
holographic theory. If the theory is in the same phase as the assumed IR fixed
point, the initial state is smoothly projected to the final state. If in a
different phase, the initial state undergoes a phase transition which in turn
gives rise to a horizon in the bulk geometry. We demonstrate the connection
between critical behavior and horizon in an example, by deriving the bulk
metrics that emerge in various phases of the U(N) vector model in the large N
limit based on the holographic dual constructed from quantum RG. The gapped
phase exhibits a geometry that smoothly ends at a finite proper distance in the
radial direction. The geometric distance in the radial direction measures a
complexity : the depth of RG transformation that is needed to project the
generally entangled UV state to a direct product state in the IR. For gapless
states, entanglement persistently spreads out to larger length scales, and the
initial state can not be projected to the direct product state. The obstruction
to smooth projection at charge neutral point manifests itself as the long
throat in the anti-de Sitter space. The Poincare horizon at infinity marks the
critical point which exhibits a divergent length scale in the spread of
entanglement. For the gapless states with non-zero chemical potential, the bulk
space becomes the Lifshitz geometry with the dynamical critical exponent two.
The identification of horizon as critical point may provide an explanation for
the universality of horizon. We also discuss the structure of the bulk tensor
network that emerges from the quantum RG. | hep |
Physics at the Photon Linear Collider: The physics prospects of the high energy Photon Linear Collider are reviewed,
emphasizing its potential to study the symmetry breaking sector, including
Higgs searches and precision anomalous W couplings measurements. | hep |
Hard exclusive electroproduction of two pions and their resonances: We study the hard exclusive production of two pions in the virtual photon
fragmentation region with various invariant masses including the resonance
region. The amplitude is expressed in terms of two-pion light cone distribution
amplitudes ($2\pi$DA's). We derive dispersion relations for these amplitudes,
which enables us to fix them completely in terms of $\pi\pi$ scattering phases
and a few low-energy subtraction constants determind by the effective chiral
lagrangian. Quantitative estimates of the resonance as well $\pi\pi$ background
DA's at low normalization point are made. We also prove certain new soft pion
theorem relating two-pion DA's to the one-pion DA. Crossing relations between
$2\pi$DA's and parton distributions in a pion are discussed.
We demontrate that by studying the shape of the $\pi\pi$ mass spectra (not
absolute cross section!) in a diffractive electroproduction one can extract the
deviation of the meson ($\pi,\rho,$ etc.) wave functions from their asymptotic
form $6 z(1-z)$ and hence to get important information about the structure of
mesons. Also we discuss how the moments of quark distributions in a pion can be
measured in the hard diffraction. We suggest (alternative to S\"oding's)
parametrization of $\pi\pi$ spectra which is suitable for large photon
virtuality. | hep |
Boundary-to-bulk maps for AdS causal wedges and RG flow: We consider the problem of defining spacelike-supported boundary-to-bulk
propagators in AdS$_{d+1}$ down to the unitary bound $\Delta=(d-2)/2$. That is
to say, we construct the `smearing functions' $K$ of HKLL but with different
boundary conditions where both dimensions $\Delta_+$ and $\Delta_-$ are taken
into account. More precisely, we impose Robin boundary conditions, which
interpolate between Dirichlet and Neumann boundary conditions and we give
explicit expressions for the distributional kernel $K$ with spacelike support.
This flow between boundary conditions is known to be captured in the boundary
by adding a double-trace deformation to the CFT. Indeed, we explicitly show
that using $K$ there is a consistent and explicit map from a Wightman function
of the boundary QFT to a Wightman function of the bulk theory. In order to
accomplish this we have to study first the microlocal properties of the
boundary two-point function of the perturbed CFT and prove its wavefront set
satisfies the microlocal spectrum condition. This permits to assert that $K$
and the boundary two-point function can be multiplied as distributions. | hep |
Improved AdS/QCD Model with Matter: We study an improved AdS/QCD model at finite temperature and chemical
potential. An Ansatz for the beta-function for the boundary theory allows for
the derivation of a charged dilatonic black hole in bulk. The solution is
asymptotically RN-AdS in the UV and AdS2 * R3 in the IR. We discuss the
thermodynamical aspects of the solution. The fermionic susceptibilities are
shown to deviate from the free fermionic limits at asymptotic temperatures
despite the asymptotically free nature of the gauge coupling at the boundary.
The Polyakov line, the temporal and spatial string tensions dependence on both
temperature and chemical potential are also discussed. | hep |
B decays into radially excited charmed mesons: It has been recently argued that some longstanding problems in semileptonic B
decays can be solved provided the branching ratio for the $B\to
D^{\prime(\ast)}$ semileptonic decays are large enough. We have studied these
decays in a constituent quark model which has been successful in describing
semileptonic and non-leptonic B decays into orbitally excited charmed mesons.
Our results do not confirm the hypothesis of large branching ratios for the
$B\to D^{\prime(\ast)}$ semileptonic decays. In addition, we calculate the
non-leptonic $B\to D'\pi$ decays which can provide an independent test of the
form factors involved in the $B\to D^{\prime(\ast)}$ reactions. | hep |
Massive IIA Supergravity as a Non-linear Realisation: A description of the bosonic sector of massive IIA supergravity as a
non-linear realisation is given. An essential feature of this construction is
that the momentum generators have non-trivial commutation relations with the
generators associated with the gauge fields. | hep |
Neutrino oscillations in de Sitter space-time: We try to understand flavor oscillations and to develop the formulae for
describing neutrino oscillations in de Sitter space-time. First, the covariant
Dirac equation is investigated under the conformally flat coordinates of de
Sitter geometry. Then, we obtain the exact solutions of the Dirac equation and
indicate the explicit form of the phase of wave function. Next, the concise
formulae for calculating the neutrino oscillation probabilities in de Sitter
space-time are given. Finally, The difference between our formulae and the
standard result in Minkowski space-time is pointed out. | hep |
SU(2) Gauge Theory in $2+1$ Dimensions on a Plaquette Chain Obeys the
Eigenstate Thermalization Hypothesis: We test the eigenstate thermalization hypothesis (ETH) for 2+1 dimensional
SU(2) lattice gauge theory. By considering the theory on a chain of plaquettes
and truncating basis states for link variables at $j=1/2$, we can map it onto a
quantum spin chain with local interactions and numerically exactly diagonalize
the Hamiltonian for reasonably large lattice sizes. We find energy level
repulsion in momentum sectors with no remaining discrete symmetry. We study two
local observables made up of Wilson loops and calculate their matrix elements
in the energy eigenbasis, which are shown consistent with the ETH. | hep |
Neutrino Large Mixing in Universal Yukawa Coupling Model with Small
Violation: We have analyzed the possibility that the universal Yukawa coupling
(democratic mass matrix) with small violations of Dirac and Majorana neutrinos
can induce the large mixing of neutrinos through the seesaw mechanism. The
possibility can be achieved by the condition that the violation parameters of
Majorana neutrinos are sufficiently smaller than the violation parameters of
Dirac neutrinos. Allowed regions of the violation parameters producing the
observed neutrino mass hierarchy and large neutrino mixing are not so
restricted at present in contrast to the violation parameters for quark sector. | hep |
Scalar mesons within a dynamical holographic QCD model: We show that the infrared dynamics of string modes dual to $q\bar q$ states
within a Dynamical AdS/QCD model of coupled dilaton-gravity background gives
the Reggelike spectrum of $f0's$ scalars and higher spin mesons consistent with
experimental data. The pion mass and its trajectory were also described with a
scale deformation of the metric and a rescaled string mass. The available
experimental decay widths of the $S\to PP$ decays provided a complementary
check of the proposed classification scheme for$f_0(980)$, $f_0(1370)$,
$f_0(1500)$ and $f_0(1710)$ as radial excitations of $f_0(600)$. For $f_0(980)$
we estimated a mixing angle of $\pm 20^o$ with other structures. | hep |
SU(N) Skyrmions from Instantons: Atiyah and Manton have outlined a scheme to obtain approximations to the
SU(2) skyrmions from instantons in $\R^4$. In this paper we apply this scheme
to construct, in an explicit form, approximations to static spherically
symmetric SU(N) skyrmions with various baryon numbers. In particular we show
how to obtain the skyrmions from instantons using harmonic maps into complex
projective spaces. | hep |
Cost-Effective Clustering: Small Beowulf clusters can effectively serve as personal or group
supercomputers. In such an environment, a cluster can be optimally designed for
a specific problem (or a small set of codes). We discuss how theoretical
analysis of the code and benchmarking on similar hardware lead to optimal
systems. | hep |
Moduli-dependent Calabi-Yau and SU(3)-structure metrics from Machine
Learning: We use machine learning to approximate Calabi-Yau and SU(3)-structure
metrics, including for the first time complex structure moduli dependence. Our
new methods furthermore improve existing numerical approximations in terms of
accuracy and speed. Knowing these metrics has numerous applications, ranging
from computations of crucial aspects of the effective field theory of string
compactifications such as the canonical normalizations for Yukawa couplings,
and the massive string spectrum which plays a crucial role in swampland
conjectures, to mirror symmetry and the SYZ conjecture. In the case of SU(3)
structure, our machine learning approach allows us to engineer metrics with
certain torsion properties. Our methods are demonstrated for Calabi-Yau and
SU(3)-structure manifolds based on a one-parameter family of quintic
hypersurfaces in $\mathbb{P}^4.$ | hep |
Braneworld Flux Inflation: We propose a geometrical model of brane inflation where inflation is driven
by the flux generated by opposing brane charges and terminated by the collision
of the branes, with charge annihilation. We assume the collision process is
completely inelastic and the kinetic energy is transformed into the thermal
energy after collision. Thereafter the two branes coalesce together and behave
as a single brane universe with zero effective cosmological constant. In the
Einstein frame, the 4-dimensional effective theory changes abruptly at the
collision point. Therefore, our inflationary model is necessarily 5-dimensional
in nature. As the collision process has no singularity in 5-dimensional
gravity, we can follow the evolution of fluctuations during the whole history
of the universe. It turns out that the radion field fluctuations have a steeply
tilted, red spectrum, while the primordial gravitational waves have a flat
spectrum. Instead, primordial density perturbations could be generated by a
curvaton mechanism. | hep |
$CP$ violation for $B^+_{c}\rightarrow D_{(s)}^+π^+π^-$ in
Perturbative QCD: In the perturbative QCD (PQCD) approach we study the direct $CP$ violation in
$B^+_{c}\rightarrow D_{(s)}^+\rho^0(\omega) \rightarrow D_{(s)}^+\pi^+\pi^-$
via the $\rho-\omega$ mixing mechanism. We find that the $CP$ violation can be
enhanced by $\rho-\omega$ mixing when the invariant masses of the $\pi^+\pi^-$
pairs are in the vicinity of the $\omega$ resonance. For the decay process
$B^+_{c}\rightarrow D^+\rho^0(\omega) \rightarrow D^+\pi^+\pi^-$, the maximum
$CP$ violation can reach 7.5 {\%}. | hep |
Testing $Z$ boson rare decays $Z\to H_1 γ, A_1 γ$ with
$(g-2)_μ$, $δM_W$, and $BR(h_{\rm SM}\to Zγ)$ in the NMSSM: We study the rare decay process of $Z$ boson into photon, accompanied by a
CP-even or CP-odd scalar. We present the analytical delineation of the
processes through the model-independent parametrizations of the new physics
couplings and, finally, consider the Next-to-Minimal Supersymmetric Standard
Model to mark out the parameter space where the branching fraction can have the
maximum value. As a part of the necessary phenomenological and experimental
cross-checks, we aim to fit the anomalous magnetic moment of the muon and $W$
boson mass anomaly through the supersymmetric contributions. We also find that
the decays $Z\to H_1 \gamma, A_1 \gamma$ can serve as an excellent
complementary test to $BR(h_{\rm SM}\to Z\gamma)$. In fact, to facilitate
future searches, we unveil a few benchmark points that additionally satisfy the
deviation of $BR(h_{\rm SM}\to Z\gamma)$ from the SM value based on the recent
measurements of ATLAS and CMS. Future proposals such as ILC, CEPC, and FCC-ee
are anticipated to operate for multiple years, focusing on center-of-mass
energy near the $Z$ pole. Consequently, these projects will be capable of
conducting experiments at the Giga-$Z$ ($10^{9}$ of $Z$ bosons) and Tera-$Z$
($10^{12}$ of $Z$ bosons) phases, which may probe the aforesaid rare decay
processes, thus the model as well. These unconventional yet complementary
searches offer different routes to explore the supersymmetric models with
extended Higgs sectors like NMSSM. | hep |
Emergent Time and the M5-Brane: We consider the maximal super-Yang-Mills theory in 5 Euclidean dimensions
with SO(5) R-symmetry and 16 supersymmetries. We argue that the strong coupling
limit of this theory (with a possible UV completion) has an emergent time
dimension and gives a description of the 5+1 dimensional Lorentz invariant
(2,0) theory of the M5-brane, compactified on a timelike circle with radius
R=g^2/4\pi^2 . Our discussion involves issues of quantization of Euclidean
theories without time. | hep |
Non-perturbative bottom PDF and its possible impact on new physics
searches: Heavy quark parton distribution functions (PDFs) play an important role in
several Standard Model and New Physics processes. Most PDF analyses rely on the
assumption that the charm and bottom PDFs are generated perturbatively by gluon
splitting and do not include any non-perturbative degrees of freedom. However,
a non-perturbative, intrinsic heavy quark PDFs have been predicted in the
literature. We demonstrate that to a very good approximation the
scale-evolution of the intrinsic heavy quark content of the nucleon is governed
by non-singlet evolution equations, and use this approximation to model the
intrinsic bottom distribution and its impact on parton-parton luminosities at
the LHC. | hep |
Generalized W-algebras and Integrable Hierarchies: We report on generalizations of the KdV-type integrable hierarchies of
Drinfel'd and Sokolov. These hierarchies lead to the existence of new classical
$W$-algebras, which arise as the second Hamiltonian structure of the
hierarchies. In particular, we present a construction of the $W_n^{(l)}$
algebras. | hep |
Effects of quark GPDs in meson electroproduction: We analyze light meson electroproduction in the intermediate energy range
where the quark contributions are essential. Our calculations are carried out
on the basis of the handbag approach. We study cross sections and spin
asymmetries for various vector and pseudoscalar mesons. Our results are in good
agrement with COMPASS and HERMES experiments. | hep |
Search for $C=+$ charmonium states in $e^+e^-\to γ+~X$ at
BEPCII/BESIII: We extend our original study in Ref. [1] on the production of $C=+$
charmonium states $X=\eta_c(1S/2S)$ and $\chi_{cJ}(1P/2P)$ in
$e^+e^-\to\gamma~+~X$ at B factories to the BEPCII/BESIII energy region with
$\sqrt{s}=4.0\mbox{-}5.0$ GeV. In the framework of nonrelativistic QCD
factorization, the cross sections are estimated to be as large as
$0.1\mbox{-}0.9$ pb. The results could be used to search for the missing $2P$
charmonium states or to estimate the continuum backgrounds in the resonance
region. | hep |
QCD Isospin Breaking in Meson Masses, Decay Constants and Quark Mass
Ratios: The procedure to calculate masses and matrix-elements in the presence of
mixing of the basis states is explained in detail. We then apply this procedure
to the two-loop calculation in Chiral Perturbation Theory of pseudoscalar
masses and decay constants including quark mass isospin breaking. These results
are used to update our analysis of $K_{\ell4}$ done previously and obtain a
value of $m_u/m_d$ in addition to values for the low-energy-constants $L_i^r$. | hep |
Bosonization approach for "atomic collapse" in graphene: We study quantum electrodynamics with 2+1 dimensional massless Dirac fermion
around a Coulomb impurity. Around a large charge with atomic number Z > 137,
the QED vacuum is expected to collapse due to the strong Coulombic force. While
the relativistic quantum mechanics fails to make reliable predictions for the
fate of the vacuum, the heavy ion collision experiment also does not give clear
understanding of this system. Recently, the "atomic collapse" resonances were
observed on graphene where an artificial nuclei can be made. In this paper, we
present our nonperturbative study of the vacuum structure of the quasiparticles
in graphene with a charge impurity which contains multi-body effect using
bosonization method. | hep |
Spectral probes of the holographic Fermi groundstate: dialing between
the electron star and AdS Dirac hair: We argue that the electron star and the AdS Dirac hair solution are two
limits of the free charged Fermi gas in AdS. Spectral functions of holographic
duals to probe fermions in the background of electron stars have a free
parameter that quantifies the number of constituent fermions that make up the
charge and energy density characterizing the electron star solution. The strict
electron star limit takes this number to be infinite. The Dirac hair solution
is the limit where this number is unity. This is evident in the behavior of the
distribution of holographically dual Fermi surfaces. As we decrease the number
of constituents in a fixed electron star background the number of Fermi
surfaces also decreases. An improved holographic Fermi groundstate should be a
configuration that shares the qualitative properties of both limits. | hep |
Duality and Canonical Transformations: We present a brief review on the canonical transformation description of some
duality symmetries in string and gauge theories. In particular, we consider
abelian and non-abelian T-dualities in closed and open string theories as well
as S-duality in abelian and non-abelian non-supersymmetric gauge theories. | hep |
Center vortex model for the infrared sector of SU(3) Yang-Mills theory:
Topological susceptibility: The topological susceptibility of the SU(3) random vortex world-surface
ensemble, an effective model of infrared Yang-Mills dynamics, is investigated.
The model is implemented by composing vortex world-surfaces of elementary
squares on a hypercubic lattice, supplemented by an appropriate specification
of vortex color structure on the world-surfaces. Topological charge is
generated in this picture by writhe and self-intersection of the vortex
world-surfaces. Systematic uncertainties in the evaluation of the topological
charge, engendered by the hypercubic construction, are discussed. Results for
the topological susceptibility are reported as a function of temperature and
compared to corresponding measurements in SU(3) lattice Yang-Mills theory. In
the confined phase, the topological susceptibility of the random vortex
world-surface ensemble appears quantitatively consistent with Yang-Mills
theory. As the temperature is raised into the deconfined regime, the
topological susceptibility falls off rapidly, but significantly less so than in
SU(3) lattice Yang-Mills theory. Possible causes of this deviation, ranging
from artefacts of the hypercubic description to more physical sources, such as
the adopted vortex dynamics, are discussed. | hep |
Search for Long-Lived Massive Charged Particles in 1.96 TeV $\bar{p}p}$
Collisions: We performed a signature-based search for long-lived charged massive
particles (CHAMPs) produced in 1.0 $\rm{fb}^{-1}$ of $\bar{p}p$ collisions at
$\sqrt{s}=1.96$ TeV, collected with the CDF II detector using a high
transverse-momentum ($p_T$) muon trigger. The search used time-of-flight to
isolate slowly moving, high-$p_T$ particles. One event passed our selection
cuts with an expected background of $1.9 \pm 0.2$ events. We set an upper bound
on the production cross section, and, interpreting this result within the
context of a stable scalar top quark model, set a lower limit on the particle
mass of 249 GeV/$c^2$ at 95% C.L. | hep |
A New Scale-Dependent Cosmology with the Generalized Robertson--Walker
Metric and Einstein Equation: Based on the observed increase of $\Omega _0$ as a function of cosmic scale,
the Robertson--Walker metric and the Einstein equation are generalized so that
$ \Omega_0$, $H_0$, and the age of the Universe, $t_0$, all become functions of
cosmic scales at which we observe them. The calculated local (within our
galaxy) age of the Universe is about 18 Gyr, consistent with the ages of the
oldest stars and globular clusters in our galaxy, while the ages at distant
scales are shorter than the local age, solving the age puzzle. It is also shown
that $H_0$ increases as scale increases, qualitatively consistent with the
recent observations. | hep |
SU(4) Preonic Interpretation of the HERA Positron-Jet Events: We show that our recent SU(4) generalized ``rishon'' composite model for
quarks and leptons, augmented either by the hypothesis of breaking of color
SU(3) to ``glow'' SO(3), or by the hypothesis of incomplete color
neutralization in very hard processes, leads to an interpretation of the HERA
positron-jet events as the production by color gluon exchange, followed by the
decay by color gluon emission, of the positron member of a heavy family partner
of the positron. | hep |
Holographic Fermionic Fixed Points in d=3: We present a top-down string theory holographic model of strongly interacting
relativistic 2+1-dimensional fermions, paying careful attention to the discrete
symmetries of parity and time reversal invariance. Our construction is based on
probe $D7$-branes in $AdS_5 \times S^5$, stabilized by internal fluxes. We find
three solutions, a parity and time reversal invariant conformal field theory
which can be viewed as a particular deformation of Coulomb interacting
graphene, a parity and time reversal violating but gapless field theory and a
system with a parity and time reversal violating charge gap. We show that the
Chern-Simons-like electric response function, which is generated perturbatively
at one-loop order by parity violating fermions and which is protected by a
no-renormalization theorem at orders beyond one loop, indeed appears with the
correctly quantized coefficient in the charge gapped theory. In the gapless
parity violating solution, the Chern-Simons response function obtains quantum
corrections which we compute in the holographic theory. | hep |
Local charges in involution and hierarchies in integrable sigma-models: Integrable $\sigma$-models, such as the principal chiral model,
${\mathbb{Z}}_T$-coset models for $T \in {\mathbb{Z}}_{\geq 2}$ and their
various integrable deformations, are examples of non-ultralocal integrable
field theories described by (cyclotomic) $r/s$-systems with twist function. In
this general setting, and when the Lie algebra ${\mathfrak{g}}$ underlying the
$r/s$-system is of classical type, we construct an infinite algebra of local
conserved charges in involution, extending the approach of Evans, Hassan,
MacKay and Mountain developed for the principal chiral model and symmetric
space $\sigma$-model. In the present context, the local charges are attached to
certain `regular' zeros of the twist function and have increasing degrees
related to the exponents of the untwisted affine Kac-Moody algebra
$\widehat{{\mathfrak{g}}}$ associated with ${\mathfrak{g}}$. The Hamiltonian
flows of these charges are shown to generate an infinite hierarchy of
compatible integrable equations. | hep |
Horava-Lifshitz gravity with detailed balance: Horava-Lifshitz gravity with "detailed balance" but without the
projectability assumption is discussed. It is shown that detailed balance is
quite efficient in limiting the proliferation of couplings in Horava-Lifshitz
gravity, and that its implementation without the projectability assumption
leads to a theory with sensible dynamics. However, the (bare) cosmological
constant is restricted to be large and negative. | hep |
Recurrence relations for toric N=1 superconformal blocks: General 1-point toric blocks in all sectors of N=1 superconformal field
theories are analyzed. The recurrence relations for blocks coefficients are
derived by calculating their residues and large $\Delta$ asymptotics. | hep |
Determining Heavy Mass Parameters in Supersymmetric SO(10) Models: Extrapolations of soft scalar mass parameters in supersymmetric theories can
be used to explore elements of the physics scenario near the grand unification
scale. We investigate the potential of this method in the lepton sector of
SO(10) which incorporates right-handed neutrino superfields. The method is
exemplified in two models by exploring limits on the precision that can be
expected from coherent LHC and e+e- collider analyses in the reconstruction of
the fundamental scalar mass parameters at the unification scale and of the
D-terms related to the breaking of grand unification symmetries. In addition,
the mass of the third-generation right-handed neutrino can be estimated in
seesaw scenarios. Even though the models are simplified and not intended to
account for all aspects of a final comprehensive SO(10) theory, they provide
nevertheless a valid base for identifying essential elements that can be
inferred on the fundamental high-scale theory from high-energy experiments. | hep |
A Phenomenological Approach to Multi-Higgs Production at High Energy: We tackle the issue of the factorial growth in the amplitudes of multi-Higgs
production at high energy by developing a phenomenological approach based on
the Higgs splitting functions and Sudakov factors. We utilize the method of
generating functionals to define several jet observables for the Higgs sector.
Our results suggest that pure Higgs splittings should retain a good UV behavior
in contrast to the common picture represented by the breakdown of perturbation
theory and violation of unitarity due to the high multiplicity of particles
produced at or near threshold, which is found in scalar theories. We thus argue
that the issue of the factorial growth in the amplitude of multi-Higgs
production is probably associated with applying perturbation theory in a regime
where it is no longer valid, as opposed to being a sign of new physics. | hep |
Omega-deformed SYM on a Gibbons-Hawking Space: We study an $\mathcal{N}=2$, pure $U(1)$ SYM theory on a Gibbons-Hawking
space $\Omega$-deformed using the $U(1)$ isometry. The resultant 3D theory,
after an appropriate "Nekrasov-Witten" change of variables, is asymptotically
equivalent to the undeformed theory at spatial infinity but differs from it as
one approaches the NUT centers which are fixed points under the $U(1)$ action.
The 3D theory may be recast in the form of a generalized hyperk\"ahler sigma
model introduced in \cite{Dey:2014lja} where the target space is a
one-parameter family of hyperk\"ahler spaces. The hyperk\"ahler fibers have a
preferred complex structure which for the deformed theory depends on the
parameter of $\Omega$-deformation. The metric on the hyperk\"ahler fiber can be
reduced to a standard metric on $\mathbb{C} \times T^2$ with the modular
parameter of the torus depending explicitly on the $\Omega$-deformation
parameter. The contribution of the NUT center to the sigma model path integral,
expected to be a holomorphic section of a holomorphic line bundle over the
target space on grounds of supersymmetry, turns out to be a Jacobi theta
function in terms of certain "deformed" variables. | hep |
On Infrared Universality in Massive Theories. Another Example: The infrared behaviour of the ${\phi}^3$-theory is discussed stressing
analogies with the Witten-Seiberg story about $N=2$ $QCD$. Though the
microscopic theory is apparently not integrable, the effective theory is shown
to be integrable at classical level, and a general solution of it in terms of
hypergeometric functions is obtained. An effective theory for the multiparticle
soft scattering is sketched. | hep |
Neutrinos at high energy accelerators: PREAMBLE, BRIEF HISTORY AND PRELIMINARIES, QUICK REVIEW OF BASIC NEUTRINO
PROPERTIES, CHARGED CURRENT NEUTRINO PROCESSES, NEUTRAL CURRENT NEUTRINO
PROCESSES, VERY HEAVY NEUTRINOS, CONCLUDING SUMMARY | hep |
Exact potential and scattering amplitudes from the tachyon non-linear
$β$-function: We compute, on the disk, the non-linear tachyon $\beta$-function, $\beta^T$,
of the open bosonic string theory. $\beta^T$ is determined both in an expansion
to the third power of the field and to all orders in derivatives and in an
expansion to any power of the tachyon field in the leading order in
derivatives. We construct the Witten-Shatashvili (WS) space-time effective
action $S$ and prove that it has a very simple universal form in terms of the
renormalized tachyon field and $\beta^T$. The expression for $S$ is well suited
to studying both processes that are far off-shell, such as tachyon
condensation, and close to the mass-shell, such as perturbative on-shell
amplitudes. We evaluate $S$ in a small derivative expansion, providing the
exact tachyon potential. The normalization of $S$ is fixed by requiring that
the field redefinition that maps $S$ into the tachyon effective action derived
from the cubic string field theory is regular on-shell. The normalization
factor is in precise agreement with the one required for verifying all the
conjectures on tachyon condensation. The coordinates in the space of couplings
in which the tachyon $\beta$-function is non linear are the most appropriate to
study RG fixed points that can be interpreted as solitons of $S$, $i.e.$
D-branes. | hep |
The Toric SO(10) F-Theory Landscape: Supergravity theories in more than four dimensions with grand unified gauge
symmetries are an important intermediate step towards the ultraviolet
completion of the Standard Model in string theory. Using toric geometry, we
classify and analyze six-dimensional F-theory vacua with gauge group SO(10)
taking into account Mordell-Weil U(1) and discrete gauge factors. We determine
the full matter spectrum of these models, including charged and neutral SO(10)
singlets. Based solely on the geometry, we compute all matter multiplicities
and confirm the cancellation of gauge and gravitational anomalies independent
of the base space. Particular emphasis is put on symmetry enhancements at the
loci of matter fields and to the frequent appearance of superconformal points.
They are linked to non-toric K\"ahler deformations which contribute to the
counting of degrees of freedom. We compute the anomaly coefficients for these
theories as well by using a base-independent blow-up procedure and
superconformal matter transitions. Finally, we identify six-dimensional
supergravity models which can yield the Standard Model with high-scale
supersymmetry by further compactification to four dimensions in an Abelian flux
background. | hep |
Gauge Invariances and Phases of Massive Higher Spins in (A)dS: The (m^2,\Lambda) plane of spin s>1 massive fields in (A)dS backgrounds is
shown to consist of separate phases, divided by lines of novel ``partially
massless'' gauge theories that successively remove helicities, starting from
the lowest, 0 or +/-(1/2). The norms of the excluded states flip as the gauge
lines are crossed and only the region containing the massive Minkowski theory
is unitary. The partially massless gauge theories are unitary or not, depending
on the ordering of the gauge lines. This ``level splitting'' of massless
Minkowski gauge theories is specific to non-zero \Lambda. | hep |
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