text
stringlengths 73
2.82k
| category
stringclasses 21
values |
|---|---|
The decay of the X(3872) into χ_{cJ} and the Operator Product
Expansion in XEFT: XEFT is a low energy effective theory for the X(3872) that can be used to
systematically analyze the decay and production of the X(3872) meson, assuming
that it is a weakly bound state of charmed mesons. In a previous paper, we
calculated the decays of X(3872) into \chi_{cJ} plus pions using a two-step
procedure in which Heavy Hadron Chiral Perturbation Theory (HH\chiPT)
amplitudes are matched onto XEFT operators and then X(3872) decay rates are
then calculated using these operators. The procedure leads to IR divergences in
the three-body decay X(3872) \to \chi_{cJ} \pi \pi when virtual D mesons can go
on-shell in tree level HH\chiPT diagrams. In previous work, we regulated these
IR divergences with the $D^{*0}$ width. In this work, we carefully analyze
X(3872) \to \chi_{cJ} \pi^0 and X(3872) \to \chi_{cJ} \pi \pi using the
operator product expansion (OPE) in XEFT. Forward scattering amplitudes in
HH\chiPT are matched onto local operators in XEFT, the imaginary parts of which
are responsible for the decay of the X(3872). Here we show that the IR
divergences are regulated by the binding momentum of the X(3872) rather than
the width of the D^{*0} meson. In the OPE, these IR divergences cancel in the
calculation of the matching coefficients so the correct predictions for the
X(3872) \to \chi_{c1} \pi \pi do not receive enhancements due to the width of
the D^{*0}. We give updated predictions for the decay X(3872) \to \chi_{c1} \pi
\pi at leading order in XEFT. | hep |
Gravity-Yang-Mills-Higgs unification by enlarging the gauge group: We revisit an old idea that gravity can be unified with Yang-Mills theory by
enlarging the gauge group of gravity formulated as gauge theory. Our starting
point is an action that describes a generally covariant gauge theory for a
group G. The Minkowski background breaks the gauge group by selecting in it a
preferred gravitational SU(2) subgroup. We expand the action around this
background and find the spectrum of linearized theory to consist of the usual
gravitons plus Yang-Mills fields charged under the centralizer of the SU(2) in
G. In addition, there is a set of Higgs fields that are charged both under the
gravitational and Yang-Mills subgroups. These fields are generically massive
and interact with both gravity and Yang-Mills sector in the standard way. The
arising interaction of the Yang-Mills sector with gravity is also standard.
Parameters such as the Yang-Mills coupling constant and Higgs mass arise from
the potential function defining the theory. Both are realistic in the sense
explained in the paper. | hep |
Shear Viscosity from AdS Born-Infeld Black Holes: We calculate the shear viscosity in the frame of AdS/CFT correspondence for
the field theory with a gravity dual of Einstein-Born-Infeld gravity. We find
that the ratio of $\eta/s$ is still the conjectured universal value $1/4\pi$ at
least up to the first order of the Born-Infeld parameter $1/b^2$. | hep |
Effect of small cosmological constant on electromagnetic memory effect: We consider a generic scattering process that takes place in a region of size
R inside the static patch of the de Sitter spacetime such that R is smaller
than the curvature length scale of the background. The effect of curvature can
thus be studied perturbatively. We obtain the asymptotic electromagnetic field
generated by the scattering process including the leading order correction due
to the presence of de Sitter background and discuss its universal aspects. We
finally caculate the resultant first order corrections to the flat spacetime
velocity memory effect. | hep |
Magnetic Moment of $Ξ_b(6227)$ as Molecular Pentaquark State: Motivated by the observation of $\Xi_b(6227)$ state, in this study
considering $\Xi_b(6227)$ has a molecular structure, we calculate magnetic
moment of this state in quark model. The magnetic moment of a hadron gives
valuable information about the internal structure and shape deformations. We
observe that orbital excitation of $\Xi_b(6227)$ molecular state change the
results of magnetic moment significantly. We also observe that light quarks in
$\Xi_b(6227)$ molecular state determine magnetic moment. Measurement of the
magnetic moment of $\Xi_b(6227)$ can clarify the nature of this state and be
useful to identify the quantum numbers. | hep |
Double spin azimuthal asymmetries A_{LT} and A_{LL} in semi-inclusive
DIS: Within the LO QCD parton model of SIDIS with unintegrated quark distribution
and fragmentation functions we study the transverse momentum and azimuthal
dependencies of the double spin asymmetries $A_{LT}$ and $A_{LL}$. For later we
include ${\cal O}(k_{\perp}/Q)$ kinematic corrections, which induce an
azimuthal modulation of the asymmetry, analogous to the Cahn effect in
unpolarized SIDIS. We show that a study of these asymmetries allows to extract
the transverse momentum dependence of the unintegrated helicity distribution
function $g_{1L}^q(x,k_\perp)$ and $g_{1T}^q(x,k_\perp)$.
This report is based on research published in [1] and [2], where predictions
are given for ongoing COMPASS, HERMES and JLab experiments. | hep |
Quantum stabilization of Z-strings in the electroweak model: We study the quantum energy of the Z-string in 2+1 dimensions using the phase
shift formalism. Our main interest is the question of stability of a Z-string
carrying a finite fermion number. | hep |
Synergies of Drell-Yan, beauty, top, and Z observables in MFV-SMEFT: The Standard Model Effective Field Theory (SMEFT) is a powerful tool to
search for new physics in a model-independent way. We explore the synergies
arising from different types of observables in a combined, global SMEFT fit.
Specifically, we investigate the combination of top-quark measurements, $b\to
s$ flavor changing neutral current transitions, $Z\to b \bar b$ and $Z\to c
\bar c$, as well as Drell-Yan data from the LHC. We also examine the impact of
Minimal Flavor Violation (MFV) as a flavor pattern in the global fit. We find
that the combination of high-p$_T$ with flavor physics observables provides
powerful synergies that significantly improve the fit and enable more precise
tests of various SMEFT operators. By incorporating different observables, we
are able to remove flat directions in the parameter space and infer on the
flavor structure based on the MFV parameterization. In particular, we find that
MFV significantly strengthens the constraints in comparison to a
flavor-specific approach. Furthermore, our analysis yields a prediction for the
dineutrino branching ratios ${\cal{B}}(B \to K^{(*)} \nu \bar \nu)$ within MFV,
which can be tested experimentally at Belle II. | hep |
II. The mass gap and solution of the quark confinement problem in QCD: We have investigated a closed system of equations for the quark propagator,
obtained earlier within our general approach to QCD at low energies. It implies
quark confinement (the quark propagator has no pole, indeed), as well as the
dynamical breakdown of chiral symmetry (a chiral symmetry preserving solution
is forbidded). This system can be solved exactly in the chiral limit. We have
established the space of the smooth test functions (consisting of the Green's
functions for the quark propagator and the corresponding quark-gluon vertex) in
which our generalized function (the confining gluon propagator) becomes a
continuous linear functional. It is a linear topological space $K(c)$ of the
infinitely differentiable functions (with respect to the dimensionless momentum
variable $x$), having compact support in the region $x \leq c$. We develop an
analytical formalism, the so-called chiral perturbtion theory at the
fundamental quark level, which allows one to find explicit solution for the
quark propagator in powers of the light quark masses. We also develop an
analytical formalism, which allows one to find the solution for the quark
propagator in the inverse powers of the heavy quark masses. It justifies the
use for the heavy quark propagator its free counterpart up to terms of the
order $1/m_Q^3$, where $m_Q$ is the heavy quark mass. So this solution
automatically possesses the heavy quark spin-flavor symmetry. | hep |
Higgs boson compositeness: from $e^+e^-\to ZH$ to $e^+e^-\to Z_L,W_L
+anything $: We assume that the Higgs doublet has a composite structure, respecting the
main standard model properties, and therefore called Composite Standard Model
(CSM), but leading (through Goldstone equivalence) to $Z_L$ and $W_L$ form
factors. We illustrate how such a form factor affecting the $ZZ_LH$ coupling
will be directly observable in $e^+e^-\to ZH$. We then show the spectacular
consequences which would appear in the inclusive processes $e^+e^-\to
Z_L+anything $. Such a form factor could also affect the $\gamma W^+_LW^-_L$
and $Z W^+_LW^-_L$ vertices and we show what effects this would generate in
$e^+e^-\to W^+W^-$ (especially in $e^+e^-_R\to W^+_LW^-_L$) and in $e^+e^-\to
W_L+anything $. We finally mention the $\gamma\gamma\to W^+W^-$ process and
several other processes in hadronic collisions which could be similarly
affected. | hep |
Hadron interaction with heavy quarkonia: Dynamics of hadro-quarkonium system is formulated, based on the channel
coupling of a light hadron (h) and heavy quarkonium (Q\bar{Q}) to intermediate
open-flavor heavy-light mesons (Q\bar{q}, \bar{Q}q). The resulting effective
interaction is defined by overlap integrals of meson wavefunctions and (hq\bar
q) coupling, where h is pi, rho, omega, phi, without fitting parameters.
Equations for hadro-quarkonium amplitudes and resonance positions are written
explicitly, and numerically calculated for the special case of pi Upsilon(nS)
(n=1,2,3). It is also shown, that the recently observed by Belle two peaks
Z_b(10610) and Z_b(10650) are in agreement with the proposed theory. It is
demonstrated, that theory predicts peaks at the BB*, B*B* thresholds in all
available pi Upsilon(nS) channels. Analytic nature of these peaks is
investigated, and shown to be due to a common multichannel resonance poles
close to the BB*, B*B* thresholds. The general mechanism of these
hadro-quarkonium resonances does not assume any molecular or four-quark
(tetraquark) dynamics. | hep |
Recent KLOE results on radiative kaon decays: While measuring the ratio R_K = \Gamma(K+e2(\gamma))/\Gamma(K+\mu2(\gamma)),
the KLOE Collaboration has studied the radiative process Ke2\gamma. The ratio
of the width for the Ke2\gamma decay with a positively polarized photon from
structure-dependent radiation to the inclusive K\mu2(\gamma) width is found to
be 1.484(68) 10-5. The observed radiation spectrum agrees with predictions from
chiral perturbation theory and is in contrast with predictions based on the
light front quark model. This result reduces the contribution to systematic
uncertainties on measurements of R_K. In a separate study, KLOE has measured
the ratio of the radiative Ke3\gamma decay width to the inclusive Ke3(\gamma)
width to be 924(28) 10-5. The distribution in energy and angle of the radiative
photon has been analyzed in an attempt to isolate the signature from
interference of the inner-bremsstrahlung and structure-dependent amplitudes. | hep |
Minimal warm inflation with a heavy QCD axion: We propose the first model of warm inflation in which the particle production
emerges directly from coupling the inflaton to Standard Model particles. Warm
inflation, an early epoch of sustained accelerated expansion at finite
temperature, is a compelling alternative to cold inflation, with distinct
predictions for inflationary observables such as the amplitude of fluctuations,
the spectral tilt, the tensor-to-scalar ratio, and non-gaussianities. In our
model a heavy QCD axion acts as the warm inflaton whose coupling to Standard
Model gluons sources the thermal bath during warm inflation. Axion-like
couplings to non-Abelian gauge bosons have been considered before as a
successful microphysical theory with emerging thermal friction that can
maintain finite temperature during inflation via sphaleron heating. However,
the presence of light fermions charged under the non- Abelian group suppresses
particle production, hindering a realization of warm inflation by coupling to
QCD. We point out that the Standard Model quarks can be heavy during warm
inflation if the Higgs field resides in a high-energy second minimum which
restores efficient sphaleron heating. A subsequent large reheating temperature
is required to allow the Higgs field to relax to its electroweak minimum.
Exploring a scenario in which hybrid inflation provides the large reheating
temperature, we show that future collider and beam dump experiments have
discovery potential for a heavy QCD axion taking the role of the minimal warm
inflaton. | hep |
Neutralino Dark Matter from Heavy Gravitino Decay: We propose a new scenario of non-thermal production of neutralino cold dark
matter, in which the overproduction problem of lightest supersymmetric
particles (LSPs) in the standard thermal history is naturally solved. The
mechanism requires a heavy modulus field which decays mainly to ordinary
particles releasing large entropy to dilute gravitinos produced just after
inflation and thermal relics of LSPs. Significant amount of gravitinos are also
pair-produced at the decay, which subsequently decay into the neutralinos. We
identify the regions of the parameter space in which the requisite abundance of
the neutralino dark matter is obtained without spoiling the big-bang
nucleosynthesis by injection of hadronic showers from gravitino decay. The
neutralino abundance obtained in this mechanism is insensitive to the details
of the superparticle mass spectrum, unlike the standard thermal abundance. We
also briefly mention the testability of the scenario in future experiments. | hep |
The Quantum Group Structure of 2D Gravity and Minimal Models II: The
Genus-Zero Chiral Bootstrap: The F and B matrices associated with Virasoro null vectors are derived in
closed form by making use of the operator-approach suggested by the Liouville
theory, where the quantum-group symmetry is explicit. It is found that the
entries of the fusing and braiding matrices are not simply equal to
quantum-group symbols, but involve additional coupling constants whose
derivation is one aim of the present work. Our explicit formulae are new, to
our knowledge, in spite of the numerous studies of this problem. The
relationship between the quantum-group-invariant (of IRF type) and
quantum-group-covariant (of vertex type) chiral operator-algebras is fully
clarified, and connected with the transition to the shadow world for
quantum-group symbols. The corresponding 3-j-symbol dressing is shown to reduce
to the simpler transformation of Babelon and one of the author (J.-L. G.) in a
suitable infinite limit defined by analytic continuation. The above two types
of operators are found to coincide when applied to states with Liouville
momenta going to $\infty$ in a suitable way. The introduction of
quantum-group-covariant operators in the three dimensional picture gives a
generalisation of the quantum-group version of discrete three-dimensional
gravity that includes tetrahedra associated with 3-j symbols and universal
R-matrix elements. Altogether the present work gives the concrete realization
of Moore and Seiberg's scheme that describes the chiral operator-algebra of
two-dimensional gravity and minimal models. | hep |
Complexity for Charged Thermofield Double States: We study Nielsen's circuit complexity for a charged thermofield double state
(cTFD) of free complex scalar quantum field theory in the presence of
background electric field. We show that the ratio of the complexity of
formation for cTFD state to the thermodynamic entropy is finite and it depends
just on the temperature and chemical potential. Moreover, this ratio smoothly
approaches the value for real scalar theory. We compare our field theory
calculations with holographic complexity of charged black holes and confirm
that the same cost function which is used for neutral case continues to work in
presence of $U(1)$ background field. For $t>0$, the complexity of cTFD state
evolves in time and contrasts with holographic results, it saturates after a
time of the order of inverse temperature. This discrepancy can be understood by
the fact that holographic QFTs are actually strong interacting theories, not
free ones. | hep |
An Elementary Derivation of the Black-Hole Area-Entropy Relation in Any
Dimension: A straightforward two-line derivation of the Bekenstein-Hawking Area-Entropy
relation for Black-Holes in {\bf any} dimension is shown based on Shannon's
information theory and Clifford algebras required by the New Relativity
Principle. | hep |
Hidden-charm Hexaquarks from Lattice QCD: We present a lattice QCD study of hidden-charm hexaquarks with quark content
$usc\bar{d}\bar{s}\bar{c}$ based on four ensembles of gauge configurations
generated by CLQCD Collaboration with pion mass in the range of 220-300MeV.
Four operators with quantum numbers $0^{++}, 0^{-+}, 1^{++}$ and $1^{--}$
respectively are constructed to interpolate the hexaquarks. After validating
the spectrum and the dispersion relation for ordinary hadrons, we calculate the
masses of the hexaquarks and extrapolate the results to the physical pion mass
and the continuum limit. We find that the masses of the four hexaquarks are all
below the $\Xi_c \bar \Xi_c$ threshold, while the $0^{-+}$ hexaquark lies
around the $\eta_c K^+K^-$ threshold. These results will be helpful for
experimental searches in future and for a deep understanding of the nature of
multiquark states. | hep |
The fate of horizons under quantum corrections: We have studied a lagrangian in which the Einstein-Hilbert term is deformed
by the Weyl cube operator, which is the lowest-dimension operator that is
non-vanishing on shell and appears as a two-loop counterterm. There is a
tension between the Schwarzschild de Sitter (SdS) spacetime and this operator,
which we study in some detail. | hep |
Stop Lepton Associated Production at Hadron Colliders: At hadron colliders, the search for R-parity violating supersymmetry can
probe scalar masses beyond what is covered by pair production processes. We
evaluate the next-to-leading order SUSY-QCD corrections to the associated stop
or sbottom production with a lepton through R-parity violating interactions. We
show that higher order corrections render the theoretical predictions more
stable with respect to variations of the renormalization and factorization
scales and that the total cross section is enhanced by a factor up to 70% at
the Tevatron and 50% at the LHC. We investigate in detail how the heavy
supersymmetric states decouple from the next-to-leading order process, which
gives rise to a theory with an additional scalar leptoquark. In this scenario
the inclusion of higher order QCD corrections increases the Tevatron reach on
leptoquark masses by up to 40 GeV and the LHC reach by up to 200 GeV. | hep |
Entropic f(R) Gravity: In this short paper we follow the entropic gravity approach and demonstrate
how \(f(R)\) theories of gravity can be emergent. This is done by introducing
an effective gravitational constant which is naturally arising from the
\(f(R)\)'s equations of motion. | hep |
Aspects of self-dual Yang-Mills and self-dual gravity: In this thesis, we study the all same helicity loop amplitudes in self-dual
Yang-Mills and self-dual gravity. These amplitudes have long been conjectured
to be interpreted as an anomaly and are recently linked to the UV divergence of
two-loop quantum gravity. In the first part of the thesis, we study the loop
amplitudes in self-dual Yang-Mills. We show that the four point one-loop
amplitude can be reduced to a computation of shifts, which strongly suggests a
case for an anomaly interpretation. We next propose a new formula for the
one-loop amplitudes at all multiplicity, in terms of the Berends-Giele currents
connected by an effective propagator. We prove the formula by observing that it
readily implies the correct collinear properties. To demonstrate the validity
of our formula, we do an explicit computation at 3, 4 and 5 points and
reproduce the known results. The region momenta variables play an important
role in our formula and thus it points to both the worldsheet and the momentum
twistor interpretations. In the second part of the thesis, we study the one
loop behaviour of chiral Einstein-Cartan gravity and the one-loop amplitudes in
self-dual gravity. | hep |
Perspectives in Neutrino Physics: This is a Concluding Talk, not a Summary of the Conference. I will discuss
some of the highlights that particularly impressed me (a subjective choice) and
make some comments on the status and the prospects of neutrino mass and mixing. | hep |
Comment on 'Gravitating magnetic monopole in the global monopole
spacetime': We point out a problem with the stability of composite (global-magnetic)
monopoles recently proposed by J. Spinelly, U. de Freitas and E.R. Bezerra de
Mello [Phys. Rev. D66, 024018 (2002)]. | hep |
Leading neutron production at the EIC and LHeC: estimating the impact of
the absorptive corrections: Leading neutron (LN) production in $ep$ collisions at high energies is
investigated using the color dipole formalism and taking into account
saturation effects. We update the treatment of absorptive effects and estimate
the impact of these effects on LN spectra in the kinematical range that will be
probed by the Electron Ion Collider (EIC) and by the Large Hadron electron
Collider (LHeC). We demonstrate that Feynman scaling, associated to saturation,
is not violated by the inclusion of absorptive effects. Moreover, our results
indicate that the LN spectrum is strongly suppressed at small photon
virtualities. These results suggest that absorptive effects cannot be
disregarded in future measurements of the $\gamma \pi$ cross section to be
extracted from data on leading neutron production. | hep |
Higher Derivative Supergravities in Diverse Dimensions: We survey on-shell and off-shell higher derivative supergravities in
dimensions $1\le D\le 11$. Various approaches to their construction, including
the Noether procedure, (harmonic) superspace, superform method, superconformal
tensor calculus, $S$-matrix and dimensional reduction, are summarized.
Primarily the bosonic parts of the invariants and the supertransformations of
the fermionic fields are provided. The process of going on-shell, solutions to
the Killing spinor equations, typical supersymmetric solutions, and the role of
duality symmetries in the context of $R^4, D^4 R^4$ and $D^6 R^4$ invariants
are reviewed. | hep |
Line Shapes of the Z(4430): The Belle Collaboration recently discovered the first manifestly exotic
meson: Z^+(4430), which decays into psi' pi^+ and therefore has quark content c
c-bar u d-bar. The proximity of its mass to the D_1 D-bar^* threshold has
motivated the interpretation of the Z^+ as a charm meson molecule whose
constituents are an S-wave superposition of D_1^+ D-bar^{*0}$ and D^{*+}
D-bar_1^0$. If this interpretation is correct, the small ratio of the binding
energy of the Z^+ to the width Gamma_1 of its constituent D_1 can be exploited
to predict properties of its line shapes. Its full width at half maximum in the
channel psi' pi^+ should be approximately sqrt{3} Gamma_1 = 35 MeV, which is
consistent with the measured width of the Z^+. The Z^+ should also decay into
D^* D-bar^* pi through decay of its constituent D_1. The peak in the line shape
for D^* D-bar^* pi should be at a higher energy than the peak in the line shape
for psi' pi^+ by about Gamma_1/sqrt{12} = 6 MeV. The line shape in D^* D-bar^*
pi should also be broader and asymmetric, with a shoulder on the high energy
side that can be attributed to a threshold enhancement in the production of D_1
D-bar^*. | hep |
Brane singularities and their avoidance in a fluid bulk: Using the method of asymptotic splittings, the possible singularity
structures and the corresponding asymptotic behavior of a 3-brane in a
five-dimensional bulk are classified, in the case where the bulk field content
is parametrized by an analog of perfect fluid with an arbitrary equation of
state $P=\gamma\rho$ between the `pressure' $P$ and the `density' $\rho$. In
this analogy with homogeneous cosmologies, the time is replaced by the extra
coordinate transverse to the 3-brane, whose world-volume can have an arbitrary
constant curvature. The results depend crucially on the constant parameter
$\gamma$: (i) For $\gamma>-1/2$, the flat brane solution suffers from a
collapse singularity at finite distance, that disappears in the curved case.
(ii) For $\gamma<-1$, the singularity cannot be avoided and it becomes of the
type big rip for a flat brane. (iii) For $-1<\gamma\le -1/2$, the surprising
result is found that while the curved brane solution is singular, the flat
brane is not, opening the possibility for a revival of the self-tuning
proposal. | hep |
Pion and Kaon box contribution to $a_μ^{\text{HLbL}}$: We present an evaluation of the $\pi^\pm$ and $K^\pm$ box contributions to
the hadronic light-by-light piece of the muon's anomalous magnetic moment,
$a_\mu$. The calculation of the corresponding electromagnetic form factors
(EFFs) is performed within a Dyson-Schwinger equations (DSE) approach to
quantum chromodynamics. These form factors are calculated in the so-called
rainbow-ladder (RL) truncation, following two different evaluation methods and,
subsequently, in a further improved approximation scheme which incorporates
meson cloud effects. The results are mutually consistent, indicating that in
the domain of relevance for $a_\mu$ the obtained EFFs are practically
equivalent. Our analysis yields the combined estimates of
$a_\mu^{\pi^\pm-box}=-(15.6\pm 0.2)\times 10^{-11}$ and
$a_\mu^{K^\pm-\text{box}}=-(0.48\pm 0.02)\times 10^{-11}$, in full agreement
with results previously obtained within the DSE formalism and other
contemporary estimates. | hep |
Study of RPC gas mixtures for the ARGO-YBJ experiment: The ARGO-YBJ experiment consists of a RPC carpet to be operated at the
Yangbajing laboratory (Tibet, P.R. China), 4300 m a.s.l., and devoted to the
detection of showers initiated by photon primaries in the energy range 100 GeV
- 20 TeV. The measurement technique, namely the timing on the shower front with
a few tens of particles, requires RPC operation with 1 ns time resolution, low
strip multiplicity, high efficiency and low single counting rate. We have
tested RPCs with many gas mixtures, at sea level, in order to optimize these
parameters. The results of this study are reported. | hep |
Dynamical Dark Matter and the Positron Excess in Light of AMS: The AMS-02 experiment has recently released data which confirms a rise in the
cosmic-ray positron fraction as a function of energy up to approximately 350
GeV. Over the past decade, attempts to interpret this positron excess in terms
of dark-matter decays have become increasingly complex and have led to a number
of general expectations about the decaying dark-matter particles: such
particles cannot undergo simple two-body decays to leptons, for example, and
they must have rather heavy TeV-scale masses. In this paper, by contrast, we
show that Dynamical Dark Matter (DDM) can not only match existing AMS-02 data
on the positron excess, but also accomplish this feat with significantly
lighter dark-matter constituents undergoing simple two-body decays to leptons.
Moreover, we demonstrate that this can be done without running afoul of
numerous other competing constraints from FERMI and Planck on decaying dark
matter. Finally, we demonstrate that the Dynamical Dark Matter framework makes
a fairly robust prediction that the positron fraction should level off and then
remain roughly constant out to approximately 1 TeV, without experiencing any
sharp downturns. Indeed, if we interpret the positron excess in terms of
decaying dark matter, we find that the existence of a plateau in the positron
fraction at energies less than 1 TeV may be taken as a "smoking gun" of
Dynamical Dark Matter. | hep |
Solutions of D=4 Gauged Pseudo-Supergravity: The techniques of spinorial geometry are used to classify solutions admitting
Killing spinors in the theory of minimal anti-de Sitter $N=2$, $D=4$
supergravity, where the gauge kinetic term comes with the opposite sign. There
are four classes of solutions. One class is described by metrics corresponding
to gravitational waves propagating on $AdS_2\times H^2$. The second class of
solution is a new solution corresponding to a special limiting case of the
Killing spinor. The third class of solution corresponds to fibrations over a
Lorentzian three dimensional manifold which has a Lorentzian Gauduchon-Tod
structure. The fourth class of solution is a cosmological extension of a
Majumdar-Papapetrou type solution, described by a function satisfying the wave
equation on $\mathbb{R}^{2,1}$ . | hep |
Higgs Bosons in Warped Space, from the Bulk to the Brane: In the context of warped extra-dimensional models with all fields propagating
in the bulk, we address the phenomenology of a bulk scalar Higgs boson, and
calculate its production cross section at the LHC as well as its tree-level
effects on mediating flavor changing neutral currents. We perform the
calculations based on two different approaches. First, we compute our
predictions analytically by considering all the degrees of freedom emerging
from the dimensional reduction (the infinite tower of Kaluza Klein modes (KK)).
In the second approach, we perform our calculations numerically by considering
only the effects caused by the first few KK modes, present in the 4-dimensional
effective theory. In the case of a Higgs leaking far from the brane, both
approaches give the same predictions as the effects of the heavier KK modes
decouple. However, as the Higgs boson is pushed towards the TeV brane, the two
approaches seem to be equivalent only when one includes heavier and heavier
degrees of freedom (which do not seem to decouple). To reconcile these results
it is necessary to introduce a type of higher derivative operator which
essentially encodes the effects of integrating out the heavy KK modes and
dresses the brane Higgs so that it looks just like a bulk Higgs. | hep |
Non-linear Breit-Wheeler pair production in collisions of bremsstrahlung
$γ-$quanta and a tightly focussed laser pulse: Experimental efforts toward the detection of the nonperturbative strong-field
regime of the Breit-Wheeler pair creation process plan to combine incoherent
sources of GeV $\gamma$ quanta and the coherent fields of tightly focussed
optical laser pulses. This endeavour calls for a theoretical understanding of
how the pair yields depend on the applied laser field profile. We provide
estimates for the number of produced pairs in a setup where the high-energy
radiation is generated via bremsstrahlung. Attention is paid to the role of the
transversal and longitudinal focussing of the laser field, along with the
incorporation of a Gaussian pulse envelope. We compare our corresponding
results with predictions from plane-wave models and determine the parameters of
focused laser pulses which maximize the pair yield at fixed pulse energy.
Besides, the impact of various super-Gaussian profiles for the laser pulse
envelope and its transverse shape is discussed. | hep |
The forward particle production in the energy range of 1 PeV as seen
with the Tibet hybrid experiment: We are now operating the 500 m2 Yangbajing air-shower core (YAC-II) array
near the center of the Tibet air-shower array (Tibet-III) to observe cosmic-ray
chemical composition at the knee energy region since February 2011. The first
step of YAC, called YAC-I, containing 16 detector units, was operated from May,
2009 to February, 2010. In this paper, we used the YAC-I and Tibet-III
coincident data set obtained from May, 2009 through January, 2010 to present
the electromagnetic spectrum of air shower cores at around 1015 eV energy
region. The effective live time is calculated as 100.5 days. We would like to
report the comparison of our experimental data with MC model prediction in this
paper. | hep |
Yukawa Hierarchy Transfer from Superconformal Sector and Degenerate
Sfermion Masses: We propose a new type of supersymmetric models coupled to superconformal
field theories (SCFT's), leading simultaneously to hierarchical Yukawa
couplings and completely degenerate sfermion masses. We consider models with an
extra Abelian gauge symmetry to generate hierarchical structure for couplings
between the SM sector and the SC sector. Interestingly, this hierarchy is
inversely transferred to the Yukawa couplings in the SM sector. In this type of
models, flavor-independent structure of the superconformal fixed point
guarantees that the sfermion masses of the first and the second generations are
completely degenerate at low energy. | hep |
The $N_f \,C_F^3$ contribution to the non-singlet splitting function at
four-loop order: We report a new result for the $N_f \,C_F^3$ contribution to the four-loop
anomalous dimensions of non-singlet, twist-two operators in Quantum
Chromodynamics. This result is obtained through computations of off-shell
operator matrix elements. Employing integration-by-parts reductions and
differential equations with respect to a tracing parameter allowed us to derive
analytic results valid for arbitrary Mellin moment $n$. | hep |
Experimental observation of a Rindler horizon: In this manuscript we confirm the presence of a Rindler horizon at CERN-NA63
by exploring its thermodynamics induced by the Unruh effect in their high
energy channeling radiation experiments. By linking the entropy of the emitted
radiation to the photon number, we find the measured spectrum to be a simple
manifestation of the second law of Rindler horizon thermodynamics and thus a
direct measurement of the recoil Fulling-Davies-Unruh (FDU) temperature.
Moreover, since the experiment is born out of an ultra-relativistic positron,
and the FDU temperature is defined in the proper frame, we find that
temperature boosts as a length and thus fast objects appear colder. The
spectrum also provides us with a simple setting to measure fundamental
constants, and we employ it to measure the positron mass. | hep |
Constructing the off-diagonal part of active-neutrino mass matrix from
annihilation and creation matrices in neutrino-generation space: The off-diagonal part of the active-neutrino mass matrix is constructed from
two $3\times 3$ matrices playing the role of annihilation and creation matrices
acting in the neutrino-generation space of $\nu_e, \nu_\mu, \nu_\tau$. The
construction leads to a new relation, $M_{\mu \tau} = 4\sqrt{3} M_{e \mu} $,
which predicts in the case of tribimaximal neutrino mixing that $m_3 - m_1 =
\eta (m_2 - m_1)$ with $\eta = 5.28547$. Then, the maximal possible value of
${\Delta m^2_{32}}/{\Delta m^2_{21}}$ is equal to $\eta^2 -1 = 26.9362$ and
gives $m_1 = 0$. With the experimental estimate ${\Delta m^2_{21}}\sim
8.0\times 10^{-5} {\rm eV}^2$, this maximal value, if realized, predicts
$\Delta m^2_{32} \sim 2.2\times 10^{-3} {\rm eV}^2$, near to the popular
experimental estimation $\Delta m^2_{32} \sim 2.4\times 10^{-3} {\rm eV}^2$. | hep |
Down Type Isosinglet Quarks in ATLAS: We evaluate the discovery reach of the ATLAS experiment for down type
isosinglet quarks, $D$, using both their neutral and charged decay channels,
namely the process $pp\to D\bar{D}+X$ with subsequent decays resulting in
$2\ell+2j+E^{miss}_{T}$, $3\ell+2j+E^{miss}_{T}$ and $2\ell+4j$ final states.
The integrated luminosity required for observation of a heavy quark is
estimated for a mass range between 600 and 1000 GeV using the combination of
results from different search channels. | hep |
A guide to two-dimensional conformal field theory: This is a review of two-dimensional conformal field theory including some of
the relations to integrable models. An effort is made to develop the basic
formalism in a way which is as elementary and flexible as possible at the same
time. Some advanced topics like conformal field theory on higher genus surfaces
and relations to the isomonodromic deformation problem are discussed, for other
topics we offer a first guide to the literature. | hep |
On the IR Divergences in de Sitter Space: loops, resummation and the
semi-classical wavefunction: In this paper, we revisit the infrared (IR) divergences in de Sitter (dS)
space using the wavefunction method, and explicitly explore how the resummation
of higher-order loops leads to the stochastic formalism. In light of recent
developments of the cosmological bootstrap, we track the behaviour of these
nontrivial IR effects from perturbation theory to the non-perturbative regime.
Specifically, we first examine the perturbative computation of wavefunction
coefficients, and show that there is a clear distinction between classical
components from tree-level diagrams and quantum ones from loop processes.
Cosmological correlators at loop level receive contributions from tree-level
wavefunction coefficients, which we dub classical loops. This distinction
significantly simplifies the analysis of loop-level IR divergences, as we find
the leading contributions always come from these classical loops. Then we
compare with correlators from the perturbative stochastic computation, and find
the results there are essentially the ones from classical loops, while quantum
loops are only present as subleading corrections. This demonstrates that the
leading IR effects are contained in the semi-classical wavefunction which is a
resummation of all the tree-level diagrams. With this insight, we go beyond
perturbation theory and present a new derivation of the stochastic formalism
using the saddle-point approximation. We show that the Fokker-Planck equation
follows as a consequence of two effects: the drift from the Schr\"odinger
equation that describes the bulk time evolution, and the diffusion from the
Polchinski's equation which corresponds to the exact renormalization group flow
of the coarse-grained theory on the boundary. | hep |
Conformal symmetry and its breaking in two dimensional Nearly
Anti-de-Sitter space: We study a two dimensional dilaton gravity system, recently examined by
Almheiri and Polchinski, which describes near extremal black holes, or more
generally, nearly $AdS_2$ spacetimes. The asymptotic symmetries of $AdS_2$ are
all the time reparametrizations of the boundary. These symmetries are
spontaneously broken by the $AdS_2$ geometry and they are explicitly broken by
the small deformation away from $AdS_2$. This pattern of spontaneous plus
explicit symmetry breaking governs the gravitational backreaction of the
system. It determines several gravitational properties such as the linear in
temperature dependence of the near extremal entropy as well as the
gravitational corrections to correlation functions. These corrections include
the ones determining the growth of out of time order correlators that is
indicative of chaos. These gravitational aspects can be described in terms of a
Schwarzian derivative effective action for a reparametrization. | hep |
Inclusive charmed-meson production from bottom hadron decays at the LHC: We present predictions for the inclusive productions of the D meson
originating from bottom hadrons at the CERN LHC in the general-mass
variable-flavour-number scheme at next-to-leading order. We present results
using two methods to describe the transition for $b\rightarrow D$: a two-step
transition $b\rightarrow B \rightarrow D$, based on the $b\rightarrow B$
fragmentation functions and the spectra for $B\rightarrow D$ as measured by
CLEO and a one-step transition based on the fragmentation functions for
$b\rightarrow D$. The results of both approaches are compared. | hep |
Parton distributions incorporating QED contributions: We perform a global parton analysis of deep inelastic and related
hard-scattering data, including ${\cal O}(\alpha_{\rm QED})$ corrections to the
parton evolution. Although the quality of the fit is essentially unchanged,
there are two important physical consequences. First, the different DGLAP
evolution of u and d type quarks introduces isospin violation, i.e. $u^p \neq
d^n$, which is found to be unambiguously in the direction to reduce the NuTeV
$\sin^2\theta_W$ anomaly. A second consequence is the appearance of photon
parton distributions $\gamma(x,Q^2)$ of the proton and the neutron. In
principle these can be measured at HERA via the deep inelastic scattering
processes $e N \to e\gamma X$; our predictions are in agreement with the
present data. | hep |
String cosmology from Poisson-Lie T-dual sigma models on supermanifolds: We generalize the formulation of Poisson-Lie T-dual sigma models on manifolds
to supermanifolds. In this respect, we formulate 1+1 dimensional string
cosmological models on the Lie supergroup C^3 and its dual (A_1,1 +
2A)^0_(1,0,0), which are coupled to two fermionic fields. Then, we solve the
equations of motion of the models and show that there is a essential
singularity for the metric of the original model and its dual. | hep |
Behavior near $θ=π$ of the mass gap in the 2D O(3) non-linear
sigma model: The validity of the Haldane's conjecture entails that the mass gap of the
2-dimensional O(3) non-linear sigma model with a $\theta$-term must tend to
zero as $\theta$ approaches the value $\pi$ by following a precise law. In the
present paper we extract the related critical exponents by simulating the model
at imaginary $\theta$. | hep |
Higgs scalar potential coupled to gravity in the exponential
parametrization in arbitrary gauge: We study the parametrization and gauge dependences in the Higgs field coupled
to gravity in the context of asymptotic safety. We use the exponential
parametrization to derive the fixed points for the cosmological constant,
Planck mass, Higgs mass and its coupling, keeping arbitrary gauge parameters
$\alpha$ and $\beta$, and compare the results with the linear split. We find
that the beta functions for the Higgs potential are expressed in terms of
redefined Planck mass such that the apparent gauge dependence is absent. Only
the trace mode of the gravity fluctuations couples to the Higgs potential and
it tends to decouple in the large $\beta$ limit, but the anomalous dimension
becomes large, invalidating the local potential approximation. This gives the
limitation of the exponential parametrization. There are also singularities for
some values of the gauge parameters but well away from these, we find rather
stable fixed points and critical exponents. We thus find that there are regions
for the gauge parameters to give stable fixed points and critical exponents
against the change of gauge parameters. The Higgs coupling is confirmed to be
irrelevant for the reasonable choice of gauge parameters. | hep |
On non-linear superfield versions of the vector-tensor multiplet: We propose a harmonic superspace description of the non-linear vector-tensor
N=2 multiplet. We show that there exist two inequivalent version: the old one
in which one of the vectors is the field-strength of a gauge two-form, and a
new one in which this vector satisfies a non-linear constraint and cannot be
expressed in terms of a potential. In this the new version resembles the
non-linear N=2 multiplet. We perform the dualization of both non-linear
versions and discuss the resulting K\"ahler potentials. Finally, we couple the
non-linear vector-tensor multiplet to an abelian background gauge multiplet. | hep |
PP-waves from BPS supergravity monopoles: We discuss the Penrose limit of the Chamseddine-Volkov BPS selfgravitating
monopole in four dimensional N=4 supergravity theory with non-abelian gauge
multiplets. We analyze the properties of the resulting supersymmetric pp-wave
solutions when various Penrose limits are considered. Apart from the usual
rescaling of coordinates and fields we find that a rescaling of the gauge
coupling constant to zero is required, rendering the theory abelian. We also
study the Killing spinor equations showing an enhancement of the
supersymmetries preserved by the solutions and discuss the embedding of the
pp-wave solution in $d=10$ dimensions. | hep |
Through the blackness -- high p_T hadrons probing the central region of
200 AGeV Au-Au collisions: The energy loss of high p_T partons propagating through a hot and dense
medium is regarded as a valuable tool to probe the medium created in
ultrarelativistic heavy-ion collisions. The angular correlation pattern of
hadrons associated with a hard trigger in the region of p_T ~1-2 GeV which
exhibits a dip in the expected position of the away side jet has given rise to
the idea that energy is lost predominantly to propagating collective modes
('Mach cones'). Recent measurements by the STAR collaboration have shown that
for a high p_T > 8 GeV trigger the angular pattern of associate hadrons for p_T
> 4 GeV shows the emergence of the expected away side peak. These di-jet events
suggest that the away side parton may emerge occasionally without substantial
energy loss. Since in such a back-to-back configuration one of the partons may
travel through the central region of the fireball, the average in-medium
pathlength is substantial and the expected energy loss is not only sensitive to
the initial geometry of matter but also to the change of geometry due to
expansion. We show that radiative energy loss is able to explain the dijet
events provided that the expansion of the medium is taken into account. | hep |
Monopoles and deconfinement transition in finite temperature $SU(2)$ QCD: We investigate the role of monopoles in the deconfinement transition of
finite temperature $SU(2)$ QCD in the maximally abelian gauge. In the
confinement phase a long monopole loop exists in each configuration, whereas no
long loop exists in the deep deconfinement region. Balancing of the energy and
the entropy of loops of the maximally extended monopoles can explain the
occurrence of the deconfinement transition. | hep |
Thermal modification of open heavy-flavor mesons from an effective
hadronic theory: We have developed a self-consistent theoretical approach to study the
modification of the properties of heavy mesons in hot mesonic matter which
takes into account chiral and heavy-quark spin-flavor symmetries. The
heavy-light meson-meson unitarized scattering amplitudes in coupled channels
incorporate thermal corrections by using the imaginary-time formalism, as well
as the dressing of the heavy mesons with the self-energies. We report our
results for the ground-state thermal spectral functions and the implications
for the excited mesonic states generated dynamically in the heavy-light
molecular model. We have applied these to the calculation of meson Euclidean
correlators and transport coefficients for D mesons and summarize here our
findings. | hep |
BRST approach to Lagrangian construction for fermionic higher spin
fields in AdS space: We develop a general gauge invariant Lagrangian construction for half-integer
higher spin fields in the AdS space of any dimension. Starting with formulation
in terms of auxiliary Fock space we derive the closed nonlinear symmetry
algebras of higher spin fermionic fields in the AdS space and find the
corresponding BRST operator. A universal procedure of constructing the gauge
invariant Lagrangians describing the dynamics of fermionic fields of any spin
is developed. No off-shell constraints for the fields and gauge parameters are
imposed from the very beginning. It is shown that all the constraints
determining the irreducible representation of the AdS group arise as a
consequence of the equations of motion and gauge transformations. As an example
of the general procedure, we derive the gauge invariant Lagrangians for massive
fermionic fields of spin 1/2 and 3/2 containing the total set of auxiliary
fields and gauge symmetries. | hep |
Two-loop stability of singlet extensions of the SM with dark matter: We present a study of the high energy stability of a minimal complex singlet
extension of the Standard Model with or without dark matter (CxSM). We start by
obtaining the beta functions of the couplings of the theory from the effective
potential and then perform the RGE evolution for the allowed parameter space of
the model at the electroweak scale. We obtain the scale up to which the model
survives and combine this information with all the LHC measurements as well as
bounds from dark matter detection experiments as well as the relic density best
measurement from Planck. We conclude that scenarios which solve both the dark
matter and stability problems must contain a dark particle heavier than 50 GeV
and a new visible state (mixing with the SM-like Higgs) heavier than 170 GeV. | hep |
APPLICATIONS OF EFFECTIVE LAGRANGIANS: The applications of effective lagrangians to the determination of the effects
of physics beyond the Standard Model are briefly described. Emphasis is given
to those effective operators which generate the largest deviations form the
Standard Model; some applications are described. of the paper (or other short
description) [Talk given at "Beyond the Standard Model IV", Lake Tahoe, CA,
Dec. 13-18, 1994] | hep |
Heavy Meson Radiative Decays and Light Vector Meson Dominance: Electromagnetic interactions are introduced in the effective chiral
Lagrangian for heavy mesons which includes light vector particles. A suitable
notion of vector meson dominance is formulated. The constraints on the heavy
meson -light vector and heavy meson-light pseudoscalar coupling constants are
obtained using experimental $D^* \ra D \, \gamma $ branching ratios. These
constraints are compared with values estimated from semi-leptonic transition
amplitudes as well as from extension of the light meson coupling pattern.
Application to the heavy baryon spectrum in the ``bound state " model is made. | hep |
Nilpotent (Anti-)BRST and (Anti-)co-BRST Symmetries in 2D non-Abelian
Gauge Theory: Some Novel Observations: We discuss the nilpotent Becchi-Rouet-Stora-Tyutin (BRST), anti-BRST and
(anti-)co-BRST symmetry transformations and derive their corresponding
conserved charges in the case of a two (1+1)-dimensional (2D) self-interacting
non-Abelian gauge theory (without any interaction with matter fields). We point
out a set of novel features that emerge out in the BRST and co-BRST analysis of
the above 2D gauge theory. The algebraic structures of the symmetry operators
(and corresponding conserved charges) and their relationship with the
cohomological operators of differential geometry are established, too. To be
more precise, we demonstrate the existence of a single Lagrangian density that
respects the continuous symmetries which obey proper algebraic structure of the
cohomological operators of differential geometry. In literature, such
observations have been made for the coupled (but equivalent) Lagrangian
densities of the 4D non-Abelian gauge theory. We lay emphasis on the existence
and properties of the Curci-Ferrari (CF) type restrictions in the context of
(anti-)BRST and (anti-)co-BRST symmetry transformations and pinpoint their key
differences and similarities. All the observations, connected with the
(anti-)co-BRST symmetries, are completely novel. | hep |
Instanton Effects in Matrix Models and String Effective Lagrangians: We perform an explicit calculation of the lowest order effects of single
eigenvalue instantons on the continuous sector of the collective field theory
derived from a $d=1$ bosonic matrix model. These effects consist of certain
induced operators whose exact form we exhibit. | hep |
On the Connection of Leptogenesis with Low Energy CP Violation and LFV
Charged Lepton Decays: Assuming only a hierarchical structure of the heavy Majorana neutrino masses
and of the neutrino Dirac mass matrix m_D of the see-saw mechanism, we find
that in order to produce the observed baryon asymmetry of the Universe via
leptogenesis, the scale of m_D should be given by the up-quark masses. Lepton
flavor violating decays \mu \to e + \gamma, \tau \to \mu + \gamma and \tau \to
e + \gamma are considered and a characteristic relation between their decay
rates is predicted. The effective Majorana mass in neutrinoless double beta
decay depends on the CP violating phase controlling the leptogenesis if one of
the heavy Majorana neutrinos is much heavier than the other two. Successful
leptogenesis requires a rather mild mass hierarchy between the latter. The
compatibility of this hierarchical see-saw model with the low energy neutrino
mixing phenomenology requires that the mixing angle limited by the CHOOZ and
Palo Verde experiments should be relatively large, \sin^2\theta_3 \gtap 0.01.
The CP violation effects in neutrino oscillations can be observable. In
general, there is no direct connection between the latter and the CP violation
in leptogenesis. If the CP violating phases of the see-saw model satisfy
certain relations, the baryon asymmetry of the Universe and the rephasing
invariant J_{CP} which determines the magnitude of the CP violation effects in
neutrino oscillations, depend on the same CP violating phase and their signs
are correlated. | hep |
Chiral Symmetry Restoration through Hawking-Unruh Thermalization Effect: Comments on the chiral symmetry restoration through the Hawking-Unruh effect
are given. | hep |
Precise Determination of the Weak Mixing Angle from a measurement of ALR
in e+e- -> Z0: In the 1993 SLC/SLD run, the SLD recorded 50,000 $\z0$ events produced by the
collision of longitudinally polarized electrons on unpolarized positrons at a
center-of-mass energy of 91.26 GeV. The luminosity-weighted average
polarization of the SLC electron beam was (63.0$\pm$1.1)\%. We measure the
left-right cross-section asymmetry in $\z0$ boson production, $\alr$, to be
0.1628$\pm$0.0071(stat.)$\pm$0.0028(syst.) which determines the effective weak
mixing angle to be $\swein=0.2292\pm0.0009({\rm stat.})\pm0.0004({\rm syst.}).$ | hep |
Dimensional reduction to hypersurface of foliation: When the bulk spacetime has a foliation structure, the collective dynamics of
the hypersurfaces should reveal certain aspects of the bulk physics. The
procedure of reducing the bulk to a hypersurface, called ADM reduction, was
implemented in \cite{Park:2013iqa} where the 4D Einstein-Hilbert action was
reduced along the radial reduction. In this work, reduction along the angular
directions is considered {with a main goal to firmly establish the method of
dimensional reduction to a hypersurface of foliation.} We obtain a theory on a
2D plane (the $(t,r)$-plane) and observe that novel and elaborate boundary
effects are crucial for the consistency of the reduction. The reduction leads
to a 2D interacting quantum field theory. We comment on its application to
black hole information physics. | hep |
String Field Theory Around the Tachyon Vacuum: Assuming that around the tachyon vacuum the kinetic term of cubic open string
field theory is made purely of ghost operators we are led to gauge invariant
actions which manifestly implement the absence of open string dynamics around
this vacuum. We test this proposal by showing the existence of lump solutions
of arbitrary codimension in this string field theory. The key ingredients in
this analysis are certain assumptions about the analyticity properties of
tachyon Green's functions. With the help of some further assumptions about the
properties of these Green's functions, we also calculate the ratios of tensions
of lump solutions of different dimensions. The result is in perfect agreement
with the known answers for the ratios of tensions of D-branes of different
dimensions. | hep |
One-particle reducible contribution to the one-loop scalar propagator in
a constant field: Recently, Gies and Karbstein showed that the two-loop Euler-Heisenberg
Lagrangian receives a finite one-particle reducible contribution in addition to
the well-known one-particle irreducible one. Here, we demonstrate that a
similar contribution exists for the propagator in a constant field already at
the one-loop level, and we calculate this contribution for the scalar QED case.
We also present an independent derivation of the Gies-Karbstein result using
the worldline formalism, treating the scalar and spinor QED cases in a unified
manner. | hep |
Angular analyses of exclusive $\overline{B} \to X_J \ell_1 \ell_2$
decays for spin $J \leq 4$: As an update to our previous calculation for spin $J\leq2$, we present the
angular moments for exclusive $\overline{B} \to X_J \ell_1 \ell_2$, where
$\ell_1$ is a charged massless lepton and $\ell_2$ is a charged or neutral
massless lepton, and $X_J$ is a mesonic system with spin $J\leq4$. The expected
applications include higher resonances in the $[K\pi]$ system in
$\overline{B}^0 \to K^- \pi^+ \mu^- \mu^+$ at LHCb in Run~II, and in the $[\pi
\pi]$ system for $ \overline{B} \to \pi \pi \ell^- \bar{\nu}_\ell$ at Belle~II.
For the $J\leq2$ case, we also provide a set of consistency relations among the
measured moments observables and validate them against the latest measurements
from LHCb. | hep |
Enhanced $h\rightarrow γγ$ rate in MSSM singlet extensions: We study the di-photon rate in Higgs decays within singlet extensions of the
supersymmetric standard model. In particular we point out that light charginos
as well as a light charged Higgs can significantly contribute to the
corresponding partial decay width, allowing for an explanation of the
experimental indication whithin a natural supersymmetric model. This is in
contrast to the `light stau scenario' proposed within the framework of the MSSM
which requires a large amount of electroweak fine tuning. | hep |
Quintessence models in Supergravity: Scalar field models of quintessence typically require that the expectation
value of the field today is of order the Planck mass, if we want them to
explain the observed acceleration of the Universe. This suggests that we should
be considering models in the context of supergravity. We discuss a particular
class of supergravity models and analyze their behavior under different choices
of the Kahler metric. | hep |
On a generalised bootstrap principle: The S-matrices for non-simply-laced affine Toda field theories are considered
in the context of a generalised bootstrap principle. The S-matrices, and in
particular their poles, depend on a parameter whose range lies between the
Coxeter numbers of dual pairs of the corresponding non-simply-laced algebras.
It is proposed that only odd order poles in the physical strip with positive
coefficients throughout this range should participate in the bootstrap. All
other singularities have an explanation in principle in terms of a generalised
Coleman-Thun mechanism. Besides the S-matrices introduced by Delius, Grisaru
and Zanon, the missing case ($f_4^{(1)},e_6^{(2)}$), is also considered and
provides many interesting examples of pole generation. | hep |
Analysis of the vertexes $Ω^*_QΩ_Q^*φ$,
$Ω^*_QΞ_Q^*K^*$, $Ξ_Q^*Σ^*_QK^*$ and $Σ_Q^*Σ^*_Q
ρ$ with the light-cone QCD sum rules: In this article, we parameterize the vertexes $\Omega^*_Q\Omega_Q^*\phi$,
$\Omega^*_Q\Xi_Q^*K^*$,
$\Xi_Q^*\Sigma^*_QK^*$ and $\Sigma_Q^*\Sigma^*_Q \rho$ with four tensor
structures due to Lorentz invariance, and study the corresponding four strong
coupling constants with the light-cone QCD sum rules. | hep |
D = 5 maximally supersymmetric Yang-Mills theory diverges at six loops: The connection of maximally supersymmetric Yang-Mills theory to the (2,0)
theory in six dimensions has raised the possibility that it might be
perturbatively ultraviolet finite in five dimensions. We test this hypothesis
by computing the coefficient of the first potential ultraviolet divergence of
planar (large N_c) maximally supersymmetric Yang-Mills theory in D = 5, which
occurs at six loops. We show that the coefficient is nonvanishing. Furthermore,
the numerical value of the divergence falls very close to an approximate
exponential formula based on the coefficients of the divergences through five
loops. This formula predicts the approximate values of the ultraviolet
divergence at loop orders L > 6 in the critical dimension D = 4 + 6/L. To
obtain the six-loop divergence we first construct the planar six-loop
four-point amplitude integrand using generalized unitarity. The ultraviolet
divergence follows from a set of vacuum integrals, which are obtained by
expanding the integrand in the external momenta. The vacuum integrals are
integrated via sector decomposition, using a modified version of the FIESTA
program. | hep |
Self-consistent determination of hard modes in hot QCD: We determine self-consistently the hard-quark and hard-gluon modes in hot
QCD. The damping-rate part in resummed hard-quark or hard-gluon propagators,
rather than the thermal-mass part, plays the dominant role. | hep |
Measurement of the semileptonic $CP$ asymmetry in $B^0-\overline{B}{}^0$
mixing: The semileptonic $CP$ asymmetry in $B^0-\overline{B}{}^0$ mixing, $a_{\rm
sl}^d$, is measured in proton-proton collision data, corresponding to an
integrated luminosity of 3.0 fb$^{-1}$, recorded by the LHCb experiment.
Semileptonic $B^0$ decays are reconstructed in the inclusive final states
$D^-\mu^+$ and $D^{*-}\mu^+$, where the $D^-$ meson decays into the
$K^+\pi^-\pi^-$ final state, and the $D^{*-}$ meson into the
$\overline{D}{}^0(\rightarrow K^+\pi^-)\pi^-$ final state. The asymmetry
between the numbers of $D^{(*)-}\mu^+$ and $D^{(*)+}\mu^-$ decays is measured
as a function of the decay time of the $B^0$ mesons. The $CP$ asymmetry is
measured to be $a_{\rm sl}^d = (-0.02 \pm 0.19 \pm 0.30)\%$, where the first
uncertainty is statistical and the second systematic. This is the most precise
measurement of $a_{\rm sl}^d$ to date and is consistent with the prediction
from the Standard Model. | hep |
Maximally localized states and quantum corrections of black hole
thermodynamics in the framework of a new generalized uncertainty principle: As a generalized uncertainty principle (GUP) leads to the effects of the
minimal length of the order of the Planck scale and UV/IR mixing, some
significant physical concepts and quantities are modified or corrected
correspondingly. On the one hand, we derive the maximally localized states ---
the physical states displaying the minimal length uncertainty associated with a
new GUP proposed in our previous work. On the other hand, in the framework of
this new GUP we calculate quantum corrections to the thermodynamic quantities
of the Schwardzschild black hole, such as the Hawking temperature, the entropy,
and the heat capacity, and give a remnant mass of the black hole at the end of
the evaporation process. Moreover, we compare our results with that obtained in
the frameworks of several other GUPs. In particular, we observe a significant
difference between the situations with and without the consideration of the
UV/IR mixing effect in the quantum corrections to the evaporation rate and the
decay time. That is, the decay time can greatly be prolonged in the former
case, which implies that the quantum correction from the UV/IR mixing effect
may give rise to a radical rather than a tiny influence to the Hawking
radiation. | hep |
Celestial $w_{1+\infty}$ charges and the subleading structure of
asymptotically-flat spacetimes: We study the subleading structure of asymptotically-flat spacetimes and its
relationship to the $w_{1+\infty}$ loop algebra of higher spin charges. We do
so using both the Bondi-Sachs and the Newman-Penrose formalism, via a
dictionary built from a preferred choice of tetrad. This enables us to access
properties of the so-called higher Bondi aspects, such as their evolution
equations, their transformation laws under asymptotic symmetries, and their
relationship to the Newman-Penrose and the higher spin charges. By studying the
recursive Einstein evolution equations defining these higher spin charges, we
derive the general form of their transformation behavior under BMSW symmetries.
This leads to an immediate proof that the spin 0,1 and spin $s$ brackets
reproduce upon linearization the structure expected from the $w_{1+\infty}$
algebra. We then define renormalized higher spin charges which are conserved in
the radiative vacuum at quadratic order, and show that they satisfy for all
spins the $w_{1+\infty}$ algebra at linear order in the radiative data. | hep |
The Temperley-Lieb algebra and its generalizations in the Potts and XXZ
models: We discuss generalizations of the Temperley-Lieb algebra in the Potts and XXZ
models. These can be used to describe the addition of different types of
integrable boundary terms.
We use the Temperley-Lieb algebra and its one-boundary, two-boundary, and
periodic extensions to classify different integrable boundary terms in the 2,
3, and 4-state Potts models. The representations always lie at critical points
where the algebras becomes non-semisimple and possess indecomposable
representations. In the one-boundary case we show how to use representation
theory to extract the Potts spectrum from an XXZ model with particular boundary
terms and hence obtain the finite size scaling of the Potts models. In the
two-boundary case we find that the Potts spectrum can be obtained by combining
several XXZ models with different boundary terms. As in the Temperley-Lieb case
there is a direct correspondence between representations of the lattice algebra
and those in the continuum conformal field theory. | hep |
Exploring the structure of the proton through polarization observables
in l p \to jet X: We present results for a complete set of polarization observables for jet
production in lepton proton collision, where the final state lepton is not
observed. The calculations are carried out in collinear factorization at the
level of Born diagrams. For all the observables we also provide numerical
estimates for typical kinematics of a potential future Electron Ion Collider.
On the basis of this numerical study, the prospects for the transverse single
target spin asymmetry are particularly promising. This observable is given by a
certain quark-gluon correlation function, which has a direct relation to the
transverse momentum dependent Sivers parton distribution. | hep |
New results in exclusive hard reactions: Generalized Parton Distributions offer a new way to access the quark and
gluon nucleon structure. We review recent progress in this domain, emphasizing
the need to supplement the experimental study of DVCS by its crossed version,
timelike Compton scattering (TCS), where data at high energy should appear
thanks to the study of ultraperipheral collisions at the LHC. This will open
the access to very low skewness quark and gluon GPDs. Our leading order
estimates show that the factorization scale dependence of the amplitudes is
quite high. This fact demands the understanding of higher order contributions
with the hope that they will stabilize this scale dependence. The magnitudes of
the NLO coefficient functions are not small and neither is the difference of
the coefficient functions appearing respectively in the DVCS and TCS
amplitudes. The conclusion is that extracting the universal GPDs from both TCS
and DVCS reactions requires much care. We also describe the extension of the
GPD concept to three quark operators and the relevance of their nucleon to
meson matrix elements, namely the transition distribution amplitudes (TDAs)
which factorize in hard exclusive pion electroproduction off a nucleon in the
backward region and baryon-antibaryon annihilation into a pion and a lepton
pair. We discuss the main properties of the TDAs. | hep |
Greybody Factors of Charged Dilaton Black Holes in 2 + 1 Dimensions: We have studied scalar perturbations of charged dilaton black holes in 2+1
dimensions. The black hole considered here is a solution to the low-energy
string theory in 2+1 dimensions. The exact decay rates and the grey body
factors for the massless minimally coupled scalar is computed for both the
charged and the uncharged dilaton black holes. The charged and the uncharged
black hole show similar behavior for grey body factors, reflection coefficients
and decay rates. | hep |
Thermodynamics of the Reissner-Nordström-de Sitter Spacetime with
Quintessence: For Anti-de Sitte (AdS) black holes, the isochoric heat capacity of system is
vanished, while the isobaric heat capacity is not. However, this situation does
not hold on for de Sitter (dS) black holes. In this work, by introducing the
interaction between the black hole horizon and the cosmological horizon of the
Reissner-Nordstr\"om-de Sitter (RNdS) spacetime with quintessence, we discuss
the phase transition of this system. The results show that the spacetime not
only has the similar phase transition behavior to that of Van der Waals (VdW)
system, and the non-vanishing isochoric heat capacity fulfills the whole
thermodynamics system. Through the discussion of the entropic force between two
horizons, we find out the role of entropic force in the evolution of spacetime.
In addition, we also study the influence of various parameters on the phase
transition and entropic force, which will provide a new method for exploring
the interaction among black hole molecules from a micro perspective. | hep |
Aharonov-Bohm Radiation of Fermions: We analyze Aharonov-Bohm radiation of charged fermions from oscillating
solenoids and cosmic strings. We find that the angular pattern of the radiation
has features that differ significantly from that for bosons. For example,
fermionic radiation in the lowest harmonic is approximately isotropically
distributed around an oscillating solenoid, whereas for bosons the radiation is
dipolar. We also investigate the spin polarization of the emitted
fermion-antifermion pair. Fermionic radiation from kinks and cusps on cosmic
strings is shown to depend linearly on the ultraviolet cut-off, suggesting
strong emission at an energy scale comparable to the string energy scale. | hep |
The dissipative potential induced by QCD at finite temperature and
density: In the framework of QCD at finite temperature we have obtained dissipative
terms for the effective potential between $q$ and $\bar q$ which would partly
explain the $J/\psi$ suppression in the Quark Gluon Plasma (QGP). The
derivation of the dissipative potential for QGP is presented and the case for
Hadron Matter (HM) is briefly discussed. The suppression effects are estimated
based on simple approximations. | hep |
Heavy Quark Symmetry: We review the current status of heavy quark symmetry and its applications to
weak decays of hadrons containing a single heavy quark. After an introduction
to the underlying physical ideas, we discuss in detail the formalism of the
heavy quark effective theory, including a comprehensive treatment of symmetry
breaking corrections. We then illustrate some nonperturbative approaches, which
aim at a dynamical, QCD-based calculation of the universal form factors of the
effective theory. The main focus is on results obtained using QCD sum rules.
Finally, we perform an essentially model-independent analysis of semileptonic
$B$ meson decays in the context of the heavy quark effective theory. | hep |
Improving the Effective Potential:Multi-Mass-Scale Case: Previously proposed procedure for improving the effective potential by using
renormalization group equation (RGE) is generalized so as to be applicable to
any system containing several different mass scales. If one knows L-loop
effective potential and (L+1)-loop RGE coefficient functions, this procedure
gives an improved potential which satisfies the RGE and contains all of the
leading, next-to-leading,..., and L-th-to-leading log terms. Our procedure here
also clarifies how naturally the so-called effective field theory can be
incorporated in the RGE in MS bar scheme. | hep |
A precise determination of the psibar-psi anomalous dimension in
conformal gauge theories: A strategy for computing the psibar-psi anomalous dimension at the fixed
point in infrared-conformal gauge theories from lattice simulations is
discussed. The method is based on the scaling of the spectral density of the
Dirac operator or rather its integral, the mode number. It is relatively cheap,
mainly for two reasons: (a) the mode number can be determined with quite high
accuracy, (b) the psibar-psi anomalous dimension is extracted from a fit of
several observables on the same set of configurations (no scaling in the
Lagrangian parameters is needed). As an example the psibar-psi anomalous
dimension has been computed in the SU(2) theory with 2 Dirac fermions in the
adjoint representation of the gauge group, and has been found to be 0.371(20).
In this particular case, the proposed strategy has proved to be very robust and
effective. | hep |
Parton distributions and $\cos 2φ_h$ asymmetry induced by anomalous
photon-quark coupling: In the spectator models of the nucleon with scalar and axial-vector diquarks,
we show that the effect of Pauli coupling in photon-quark vertex to the parton
distribution functions (PDFs) of nucleon and azimuthal asymmetry in the
unpolarized semi-inclusive deep inelastic scattering (SIDIS). This anomalous
coupling gives obvious contribution to unpolarized and polarized PDFs, and also
leads to a $\cos 2\phi_h$ azimuthal asymmetry proportional to the squared Pauli
form factor, due to the helicity flip of the struck quark. After determining
the model parameters by fitting PDFs to the global fits, this new distribution
for $\cos 2\phi_h$ asymmetry is given numerically. In the framework of
transverse momentum dependence (TMD), we find that it is positive and of a few
percent in the kinematical regime of HERMES and COMPASS collaborations, in the
same order of magnitude with Cahn effect. | hep |
Very Special (de Sitter) Relativity: The effects of a non-vanishing value for the cosmological constant in the
scenario of Lorentz symmetry breaking recently proposed by Cohen and Glashow
(which they denote as Very Special Relativity) are explored and observable
consequences are pointed out. | hep |
Spin and localization of relativistic fermions and uncertainty relations: We discuss relations between several relativistic spin observables and derive
a Lorentz-invariant characteristic of a reduced spin density matrix.A
relativistic position operator that satisfies all the properties of its
nonrelativistic analog does not exist. Instead we propose two
causality-preserving positive operator-valued measures (POVMs) that are based
on projections onto one-particle and antiparticle spaces, and on the normalized
energy density. They predict identical expectation values for position. The
variances differ by less than a quarter of the squared de Broglie wavelength
and coincide in the nonrelativistic limit. Since the resulting statistical
moment operators are not canonical conjugates of momentum, the Heisenberg
uncertainty relations need not hold. Indeed, the energy density POVM leads to a
lower uncertainty. We reformulate the standard equations of the spin dynamics
by explicitly considering the charge-independent acceleration, allowing a
consistent treatment of backreaction and inclusion of a weak gravitational
field. | hep |
Hyperscaling violating Schrodinger black holes in
Einstein-Maxwell-scalar theory: We present a novel family of asymptotically Schrodinger hyperscaling
violating black holes with a generic dynamical critical exponent and an
arbitrary number of spacetime dimensions. This black hole family represents a
solution within the Einstein-Maxwell-scalar setup with a self-interaction
scalar potential where the Maxwell field is coupled to the scalar field.
Through an analysis of the curvature invariants it is observed that this
configuration is asymptotically regular for different ranges of the
hyperscaling violating exponent. Furthermore, the above mentioned solution
constitutes a gravitational candidate for describing field theories with
hyperscaling violating Schrodinger symmetry at finite temperature within the
framework of the Gravity/Condensed Matter Theory correspondence. | hep |
All the supersymmetric solutions of N=1,d=5 ungauged supergravity: We classify the supersymmetric solutions of ungauged N=1 d=5 SUGRA coupled to
vector multiplets and hypermultiplets. All the solutions can be seen as
deformations of solutions with frozen hyperscalars. We show explicitly how the
5-dimensional Reissner-Nordstrom black hole is deformed when hyperscalars are
living on SO(4,1)/SO(4) are turned on, reducing its supersymmetry from 1/2 to
1/8. We also describe in the timelike and null cases the solutions that have
one extra isometry and can be reduced to N=2,d=4 solutions. Our formulae allows
the uplifting of certain N=2,d=4 black holes to N=1,d=5 black holes on KK
monopoles or to pp-waves propagating along black strings. | hep |
A New Formula for the Gauge Charge: We present a new formula for the gauge charge in the causal formalism for the
QCD case. | hep |
General Relativistic effects in preheating: General relativistic effects in the form of metric perturbations are usually
neglected in the preheating era that follows inflation. We argue that in
realistic multi-field models these effects are in fact crucial, and the fully
coupled system of metric and quantum field fluctuations needs to be considered.
Metric perturbations are resonantly amplified, breaking the scale-invariance of
the primordial spectrum, and in turn stimulate scalar field resonances via
gravitational rescattering. This non-gravitationally dominated nonlinear growth
of gravitational fluctuations may have significant effects on the Doppler peaks
in the cosmic background radiation, primordial black hole formation,
gravitational waves and nonthermal symmetry restoration. | hep |
Strong Coupling Holography: We show that whenever a 4-dimensional theory with N particle species emerges
as a consistent low energy description of a 3-brane embedded in an
asymptotically-flat (4+d)-dimensional space, the holographic scale of
high-dimensional gravity sets the strong coupling scale of the 4D theory. This
connection persists in the limit in which gravity can be consistently
decoupled. We demonstrate this effect for orbifold planes, as well as for the
solitonic branes and string theoretic D-branes. In all cases the emergence of a
4D strong coupling scale from bulk holography is a persistent phenomenon. The
effect turns out to be insensitive even to such extreme deformations of the
brane action that seemingly shield 4D theory from the bulk gravity effects. A
well understood example of such deformation is given by large 4D Einstein term
in the 3-brane action, which is known to suppress the strength of 5D gravity at
short distances and change the 5D Newton's law into the four-dimensional one.
Nevertheless, we observe that the scale at which the scalar polarization of an
effective 4D-graviton becomes strongly coupled is again set by the bulk
holographic scale. The effect persist in the gravity decoupling limit, when the
full theory reduces to a 4D system in which the only memory about the
high-dimensional holography is encoded in the strong coupling scale. The
observed intrinsic connection between the high-dimensional flat space
holography and 4D strong coupling suggests a possible guideline for
generalization of AdS/CFT duality to other systems. | hep |
Explaining the CMS excesses, baryogenesis and neutrino masses in $E_{6}$
motivated $U(1)_{N}$ model: We study the superstring inspired $E_{6}$ model motivated $U(1)_{N}$
extension of the supersymmetric standard model to explore the possibility of
explaining the recent excess CMS events and the baryon asymmetry of the
universe in eight possible variants of the model. In light of the hints from
short-baseline neutrino experiments at the existence of one or more light
sterile neutrinos, we also study the neutrino mass matrices dictated by the
field assignments and the discrete symmetries in these variants. We find that
all the variants can explain the excess CMS events via the exotic slepton
decay, while for a standard choice of the discrete symmetry four of the
variants have the feature of allowing high scale baryogenesis (leptogenesis).
For one other variant three body decay induced soft baryogenesis mechanism is
possible which can induce baryon number violating neutron-antineutron
oscillation. We also point out a new discrete symmetry which has the feature of
ensuring proton stability and forbidding tree level flavor changing neutral
current processes while allowing for the possibility of high scale leptogenesis
for two of the variants. On the other hand, neutrino mass matrix of the
$U(1)_{N}$ model variants naturally accommodates three active and two sterile
neutrinos which acquire masses through their mixing with extra neutral fermions
giving rise to interesting textures for neutrino masses. | hep |
Aspects of the Flavour Expansion Theorem: The Flavour Expansion Theorem, which has been recently proposed as a more
general and elegant algebraic method, for the derivation of the commonly used
Mass Insertion Approximation, is revisited. The theorem is reviewed, with
respect to its straightforward applications in Flavour physics, and compared
against the standard diagrammatic flavour basis techniques, in cases where the
latter become inadequate. | hep |
A New Approach to Construct the Operator on Lattice for the Calculation
of Glueball Masses: We develop a new approach to construct the operator on lattice for the
calculation of glueball mass, which is based on the connection between the
continuum limit of the chosen operator and the quantum number $J^{PC}$ of the
state studied. The spin of the state studied is then determined uniquely and
directly in numerical simulation. Furthermore, the approach can be applied to
calculate the mass of glueball states (ground or excited states) with any spin
$J$ including $J\geq 4$. Under the quenched approximation, we present
pre-calculation results for the masses of $0^{++}$ state and $2^{++}$ state,
which are $1754(85)(86)MeV$ and $2417(56)(117)MeV$, respectively. | hep |
QCD Sum-Rule Interpretation of X(3872) with $J^{PC}=1^{++}$ Mixtures of
Hybrid Charmonium and $\bar D D^*$ Molecular Currents: QCD sum-rules are employed to determine whether the X(3872) can be described
as a mixed state that couples to $J^{PC}=1^{++}$ charmonium hybrid and $\bar D
D^*$ molecular currents. After calculating the mixed correlator of hybrid and
molecular currents, we formulate the sum-rule in terms of a mixing parameter
that interpolates between the pure molecular and hybrid scenarios. As the
mixing parameter is increased from the pure molecular case, the predicted mass
increases until it reaches a maximum value in good agreement with the X(3872)
and the resulting sum-rule analysis appears more robust than the pure molecular
case. | hep |
Study of Anomalous Couplings at a $500$~GeV $e^+e^-$ Linear Collider
with Polarized Beams: We consider the possibility of observing deviations from the Standard Model
gauge-boson self-couplings at a future $500$~GeV $e^+ e^-$ linear collider. We
concentrate on the case in which the electroweak symmetry breaking sector is
strongly interacting and there are no new resonances within reach of the
collider. We find a sensitivity to the anomalous couplings that is two orders
of magnitude higher than that achievable at LEP II. We also show how a
polarized electron beam extends the reach of the collider, allowing experiments
to probe different directions in parameter space. | hep |
Hermitean matrix model free energy: Feynman graph technique for all
genera: We present a diagrammatic technique for calculating the free energy of the
Hermitian one-matrix model to all orders of 1/N expansion in the case where the
limiting eigenvalue distribution spans arbitrary (but fixed) number of disjoint
intervals (curves). | hep |
Learning Lattice Quantum Field Theories with Equivariant Continuous
Flows: We propose a novel machine learning method for sampling from the
high-dimensional probability distributions of Lattice Field Theories, which is
based on a single neural ODE layer and incorporates the full symmetries of the
problem. We test our model on the $\phi^4$ theory, showing that it
systematically outperforms previously proposed flow-based methods in sampling
efficiency, and the improvement is especially pronounced for larger lattices.
Furthermore, we demonstrate that our model can learn a continuous family of
theories at once, and the results of learning can be transferred to larger
lattices. Such generalizations further accentuate the advantages of machine
learning methods. | hep |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.