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QCD Effective Actions at High Temperature and the Quasiparticle Picture: Transport theory is an efficient approach to derive an effective theory for
the soft modes of QCD at high temperature. It is known that the leading order
operators of this theory can be obtained from (semi-classical) kinetic
equations of quasiparticles carrying classical or quantum color charges. Higher
order operators can also be obtained. Discrepancy between these quasiparticle
models starts for dimension 4 operators, which converge in the limit of high
dimensional color representations. These quasiparticle models are reviewed and
compared. | hep-ph |
Probing Quintessence with Time Variation of Couplings: Many models of quintessence predict a time variation of the fundamental
constants as well as a composition-dependent gravity like long-range force
mediated by the cosmon. We present bounds for the cosmon coupling to matter and
radiation within a grand unified framework. The unification scale, the unified
gauge coupling and the Fermi scale are allowed to vary independently. We find
that the variation of the weak scale compared to the nucleon mass is severely
restricted. The violation of the equivalence principle turns out to be
substantially larger than in models where only the electromagnetic fine
structure constant varies with time. We also show that in contrast to gravity
the local cosmon field in a condensed object does not decouple from the
cosmological evolution. In consequence, the cosmon interaction constitutes a
possible quantitative link between cosmological observations and several areas
of high precision experiments concerning the local time or space variation of
couplings and tests of the equivalence principle. | hep-ph |
Isospin-conserving hadronic decay of the ${D_{s1}(2460)}$ into
${D_sπ^+π^-}$: The internal structure of the charm-strange mesons $D_{s0}^*(2317)$ and
$D_{s1}(2460)$ are subject of intensive studies. Their widths are small because
they decay dominantly through isospin-breaking hadronic channels
$D_{s0}^*(2317)^+\to D_s^+\pi^0$ and $D_{s1}(2460)^+\to D_s^{*+}\pi^0$. The
$D_{s1}(2460)$ can also decay into the hadronic final states $D_s^+\pi\pi$,
conserving isospin. In that case there is, however, a strong suppression from
phase space. We study the transition $D_{s1}(2460)^+\to D_s^+\pi^+\pi^-$ in the
scenario that the $D_{s1}(2460)$ is a $D^*K$ hadronic molecule. The $\pi\pi$
final state interaction is taken into account through dispersion relations. We
find that the ratio of the partial widths of the $\Gamma(D_{s1}(2460)^+\to
D_s^+\pi^+\pi^-)/\Gamma(D_{s1}(2460)^+\to D_s^{*+}\pi^0)$ obtained in the
molecular picture is consistent with the existing experimental measurement.
More interestingly, we demonstrate that the $\pi^+\pi^-$ invariant mass
distribution shows a double bump structure, which can be used to disentangle
the hadronic molecular picture from the compact state picture for the
$D_{s1}(2460)^+$. Predictions on the $B_{s1}^0\to B_s^0\pi^+\pi^-$ are also
made. | hep-ph |
A comparison between direct and indirect dark matter search: We carry out a comparison between different kinds of experiments for the
detection of neutralino dark matter. In particular, we compare the theoretical
predictions for the direct detection of these particles, through their elastic
scattering on target nuclei through nuclear recoils, with those for their
indirect detection through the gamma rays produced by their annihilation in the
galactic center. For the comparison we pay special attention to points which
will be testable by very sensitive experiments, such as e.g. EDELWEISS II and
GENIUS for direct detection, and GLAST for indirect detection. We perform the
analysis in the framework of a general SUGRA theory, allowing the presence of
non-universal soft scalar and gaugino masses in the parameter space. As a
conclusion, we find that indirect detection experiments will be able to test
larger regions of the parameter space than direct detection ones. | hep-ph |
Deconfinement and Chiral Symmetry Restoration in a Strong Magnetic
Background: We perform a model study of deconfinement and chiral symmetry restoration in
a strong magnetic background. We use a Nambu-Jona Lasinio model with the
Polyakov loop, taking into account a possible dependence of the coupling on the
Polyakov loop expectation value, as suggested by the recent literature. Our
main result is that, within this model, the deconfinement and chiral crossovers
of QCD in strong magnetic field are entangled even at the largest value of $eB$
considered here, namely $eB=30 m_\pi^2$ (that is, $B \approx 6\times 10^{15}$
Tesla). The amount of split that we measure is, at this value of $eB$, of the
order of 2%. We also study briefly the role of the 8-quark term on the
entanglement of the two crossovers. We then compare the phase diagram of this
model with previous results, as well as with available Lattice data. | hep-ph |
Tests for Sivers, Boer-Mulders and transversity distributions in
difference cross sections in SIDIS: A major experimental program is presently underway to determine the Sivers,
Boer-Mulders and transversity distributions, vital for understanding the
internal structure of the nucleon. To this end we consider the Sivers,
Boer-Mulders and transversity azimuthal asymmetries of the difference cross
sections of hadrons with opposite charges in SIDIS reactions with unpolarized
and transversely polarized target l+N\to l'+h+X, h=\pi^\pm, K^\pm, h^\pm. We
show that on deuteron target these asymmetries are particularly simple and
determine the sum of the valence-quark Q_V=u_V+d_V transverse momentum
dependent distributions without any contributions from the strange or other
sea-quark functions. At present, data on these asymmetries are presented for
the integrated asymmetries i.e. the x_B- and z_h-dependent asymmetries. If data
are available in small bins in Q^2, so that Q^2-dependence can be neglected,
these expressions simplify dramatically leading to remarkably simple and
powerful tests of the simplifying assumptions used in extracting these
functions from the data. | hep-ph |
Neutron-Electron EDM Correlations in Supersymmetry and Prospects for EDM
Searches: Motivated by recent progress in experimental techniques of electric dipole
moment (EDM) measurements, we study correlations between the neutron and
electron EDMs in common supersymmetric models. These include minimal
supergravity (mSUGRA) with small CP phases, mSUGRA with a heavy SUSY spectrum,
the decoupling scenario and split SUSY. In most cases, the electron and neutron
EDMs are found to be observable in the next round of EDM experiments. They
exhibit certain correlation patterns. For example, if d_n ~ 10^{-27} e cm is
found, d_e is predicted to lie in the range 10^{-28}-10^{-29} e cm. | hep-ph |
Jet quenching in heavy ion collisions at LHC: We discuss the potential information about highly excited QCD-matter provided
by medium-induced partonic energy loss, known as ``jet quenching''. In
particular, with its large acceptance hadronic and electromagnetic calorimetry,
the Compact Muon Solenoid detector at LHC collider is a promising device to
study these effects. We present physics simulations of observables such as the
jet distribution with impact parameter, the azimuthal anisotropy of jet
quenching, and the effects of b-quark energy loss on the high-mass dimuon
continuum and secondary charmonium production. | hep-ph |
Interactions of the doubly charmed state $T_{cc} ^+$ with a hadronic
medium: We investigate the absorption and production processes of this new state in a
hadronic medium, considering the reactions $T_{cc}^+ \pi, T_{cc}^+ \rho
\rightarrow D^{(*)} D^{(*)} $ and the corresponding inverse reactions. We use
effective field Lagrangians to account for the couplings between light and
heavy mesons, and give special attention to the form factors in the vertices.
We calculate here for the first time the $ T_{cc}^+ - D - D^*$ form factor
derived from QCD sum rules. The results are also obtained by testing widely
utilized empirical form factors. The absorption cross sections are found to be
larger than the production ones. We compare our results with the only existing
estimate of these quantities, presented in a work of J.~Hong, S.~Cho, T.~Song
and S.~H.~Lee, in which the authors employed the quasi-free approximation. We
find cross sections which are one order of magnitude smaller. | hep-ph |
LUXE-NPOD: new physics searches with an optical dump at LUXE: We propose a novel way to search for feebly interacting massive particles,
exploiting two properties of systems involving collisions between high energy
electrons and intense laser pulses. The first property is that the
electron-intense-laser collision results in a large flux of hard photons, as
the laser behaves effectively as a thick medium. The second property is that
the emitted photons free-stream inside the laser and thus for them the laser
behaves effectively as a very thin medium. Combining these two features implies
that the electron-intense-laser collision is an apparatus which can efficiently
convert UV electrons to a large flux of hard, co-linear photons. We further
propose to direct this unique large and hard flux of photons onto a physical
dump which in turn is capable of producing feebly interacting massive
particles, in a region of parameters that has never been probed before. We
denote this novel apparatus as ``optical dump'' or NPOD (new physics search
with optical dump). The proposed LUXE experiment at Eu.XFEL has all the
required basic ingredients of the above experimental concept. We discuss how
this concept can be realized in practice by adding a detector after the last
physical dump of the experiment to reconstruct the two-photon decay product of
a new spin-0 particle. We show that even with a relatively short dump, the
search can still be background free. Remarkably, even with a 40 TW laser, which
corresponds to the initial run, and definitely with a 350 TW laser, of the main
run with one year of data taking, LUXE-NPOD will be able to probe uncharted
territory of both models of pseudo-scalar and scalar fields, and in particular
probe natural of scalar theories for masses above 100 MeV. | hep-ph |
Selecting Supersymmetric String Scenarios From Sparticle Spectra: We approach the following question: if supersymmetry is discovered, how can
we select among different supersymmetric extensions of the Standard Model? In
particular, we perform an analysis of the sparticle spectrum in low-energy
string effective theories, asking which observables best distinguish various
scenarios. We examine scenarios differing by the fundamental string scale and
concentrate on GUT and intermediate scale models. We scan over all parameters
(two goldstino angles, tan beta and the gravitino mass) in each scenario,
finding ratios of sparticle masses that provide the maximum discrimination
between them. The necessary accuracy for discrimination is determined in each
case. We find that the required accuracy on various sparticle mass ratios is at
the few percent level, a precision that may be achieved in future linear
colliders. We also map out phenomenologically viable regions of parameter
space. | hep-ph |
The D_4 flavor symmery in 3-3-1 model with neutral leptons: We construct a $D_4$ flavor model based on SU(3)_C X SU}(3_L X U(1)_X gauge
symmetry responsible for fermion masses and mixings. The neutrinos get small
masses from antisextets which are in a singlet and a doublet under $D_4$. If
the D_4 symmetry is violated as perturbation by a Higgs triplet under SU(3)_L
and lying in {1}''' of D_4, the corresponding neutrino mass mixing matrix gets
the most general form. In this case, the model can fit the experimental data in
2012 on neutrino masses and mixing. Our results show that the neutrino masses
are naturally small and a little deviation from the tribimaximal neutrino
mixing form can be realized. The quark masses and mixing matrix are also
discussed. In the model under consideration, the CKM matrix can be different
from the unit matrix. The scalar potential of the model is more simpler than
those of the model based on $S_3$ and $S_4$. Assignation of VEVs to antisextets
leads to the mixing of the new gauge bosons and those in the Standard Model.
The mixing in the charged gauge bosons as well as the neutral gauge boson is
considered. | hep-ph |
Stitching the Yukawa Quilt: We develop a systematic analysis of quark mass matrices which, starting with
the measured values of quark masses and mixing angles, allows for a model
independent search for all possible (symmetric or hermitian) mass matrices
having texture zeroes at the unification scale. A survey of all six and five
texture zero structures yields a total of five possible solutions which may be
distinguished by improved measurements of the CKM matrix elements and which may
readily be extended to include lepton masses with the Georgi-Jarlskog texture.
The solutions naturally suggest a parameterisation for the mass matrices based
on a perturbative expansion and we present some speculations concerning the
origin of such structure. | hep-ph |
Impact of the Recoil Scheme on the Accuracy of Angular-Ordered Parton
Showers: In these proceedings we present three possible interpretations of the
ordering variable implemented in the Herwig7 angular-ordered parton shower.
Each interpretation determines a different recoil-scheme prescription and we
show how it can impact the logarithmic accuracy of the algorithm. We also
present comparisons with LEP data. | hep-ph |
$π$-$J/ψ$ Correlation and Elliptic Flow Parameter $v_2$ of Charmed
Mesons at RHIC Energy: We study the correlation between the trigger $\pi$ and the associated
$J/\psi$ on near and away sides in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV.
In the region of trigger momentum $p_t>4$ GeV/$c$, the $\pi$ spectrum is
composed of thermal-shower and shower-shower recombinations in the frame work
of the recombination model. We consider the azimuthal anisotropy in the
quenched hard parton distribution and then calculate the elliptic flow
parameter $v_2$ of charmed mesons ($J/\psi$, $D^0$ and $D_s$) for different
centralities. | hep-ph |
Dijet hadroproduction with rapidity gaps and QCD double logarithmic
effects: We show that the hadroproduction of a pair of jets with large transverse
energy in the central region bounded by rapidity gaps is an ideal process to
see important double logarithmic QCD suppression effects. We compute the cross
sections for both exclusive and inclusive double-diffractive dijet production
at Tevatron and LHC energies for a range of rapidity configurations. | hep-ph |
Sign problem and the chiral spiral on the finite-density lattice: We investigate the sign problem of the fermion determinant at finite baryon
density in (1+1) dimensions, in which the ground state in the chiral limit
should be free from the sign problem by forming a chiral spiral. To confirm it,
we evaluate the fermion determinant in the continuum theory at the one-loop
level and find that the determinant becomes real as expected. The conventional
lattice formulation to implement a chemical potential is, however, not
compatible with the spiral transformation. We discuss an alternative of the
finite-density formulation and numerically verify the chiral spiral on the
finite-density lattice. | hep-ph |
Cogenesis of Baryon Asymmetry and Gravitational Dark Matter from
Primordial Black Holes: We propose a scenario where dark matter (DM) with a wide mass range from a
few keV to PeV can be produced solely from evaporating primordial black holes
(PBH), while being consistent with the required free streaming length for
structure formation. If DM does not have any other interactions apart from
gravity and the universe has a PBH dominated phase at early epoch, then PBH
evaporation typically leads to overproduction of DM in this mass range. By
incorporating this gravitational DM within a Type-I seesaw scenario with three
right handed neutrinos (RHN), we bring the abundance of PBH generated DM within
observed limits by late entropy injection due to decay of one of the RHNs,
acting as the diluter. The diluter, due to its feeble coupling with the bath
particles, gets produced primarily from the PBH evaporation thereby leading to
the second stage of early matter domination after the end of PBH dominated era.
The other two RHNs contribute to the origin of light neutrino mass and also
lead to the observed baryon asymmetry via leptogenesis with contributions from
both thermally and PBH generated RHNs. The criteria of DM relic and baryon
asymmetry can be satisfied simultaneously if DM mass gets restricted to a
ballpark in the MeV-GeV regime with the requirement of resonant leptogenesis
for heavier DM mass in order to survive the large entropy dilution at late
epochs. | hep-ph |
Split-SUSY dark matter in light of direct detection limits: We examine the present and future XENON limits on the neutralino dark matter
in split supersymmetry (split-SUSY). Through a scan over the parameter space
under the current constraints from collider experiments and the WMAP
measurement of the dark matter relic density, we find that in the allowed
parameter space a large part has been excluded by the present XENON100 limits
and a further largish part can be covered by the future exposure (6000 kg-day).
In case of unobservation of dark matter with such an exposure in the future,
the lightest neutralino will remain bino-like and its annihilation is mainly
through exchanging the SM-like Higgs boson in order to get the required relic
density. | hep-ph |
Relativistic description of the double charmonium production in $e^+e^-$
annihilation: New evaluation of the relativistic effects in the double production of
$S$-wave charmonium states is performed on the basis of perturbative QCD and
the relativistic quark model. The main improvement consists in the exact
account of properties of the relativistic meson wave functions. For the gluon
and quark propagators entering the production vertex function we use a
truncated expansion in the ratio of the relative quark momenta to the
center-of-mass energy $\sqrt{s}$ up to the second order. The exact relativistic
treatment of the wave functions makes all such second order terms convergent,
thus allowing the reliable calculation of their contributions to the production
cross section. Compared to the nonrelativistic calculation we obtain a
significant increase of the cross sections for the $S$-wave double charmonium
production. This brings new theoretical results in good agreement with the
available experimental data. | hep-ph |
B^0_{d,s} - \bar{B}^0_{d,s} mass-differences from QCD spectral sum rules: We present the first QCD spectral sum rules analysis of the SU(3) breaking
parameter \xi and an improved estimate of the renormalization group invariant
(RGI) bag constant \hat{B}_{B_q} both entering into the B^0_{d,s} -
\bar{B}^0_{d,s} mass-differences. The averages of the results from the Laplace
and moment sum rules to order \alpha_s are f_B\sqrt{\hat B_B} \simeq (247 \pm
59) MeV and \xi \equiv f_{B_s} \sqrt{\hat B_{B_s}} / f_{B} \sqrt{\hat B_{B}}
\simeq (1.18\pm 0.03), in units where f_\pi=130.7 MeV. Combined with the
experimental data on the mass-differences \Delta M_{d,s}, one obtains the
constraint on the CKM weak mixing angle |V_{ts}/V_{td}|^2 > 20.0 (1.1).
Alternatively, using the weak mixing angle from the analysis of the unitarity
triangle and the data on \Delta M_d, one predicts \Delta M_s=18.6 (2.2) ps^{-1}
in agreement with the present experimental lower bound and within the reach of
Tevatron 2. | hep-ph |
Gravitational waves as a probe of SUSY scale: We investigate the sources of the Hubble-induced mass for a flat direction in
supersymmetric theories and show that the sign of the Hubble-induced mass
generally changes just after the end of inflation. This implies that global
cosmic strings generally form after the end of inflation in most supersymmetric
models, including the Minimal Supersymmetric Standard Model. The cosmic strings
emit gravitational waves whose frequency corresponds to the Hubble scale, until
they disappear when the Hubble parameter decreases down to the soft mass of the
flat direction. As a result, the peak frequency of gravitational waves is
related to the supersymmetric scale. The observation of this gravitational wave
signal will give us information of supersymmetric scale and reheating
temperature. | hep-ph |
The $η- η'$ Mixing Angle Revisited: The value of the $\eta - \eta'$ mixing angle $\theta_P$ is phenomenologically
deduced from a rather exhaustive and up-to-date analysis of data including
strong decays of tensor and higher-spin mesons, electromagnetic decays of
vector and pseudoscalar mesons, $J/\psi$ decays into a vector and a
pseudoscalar meson, and other transitions. A value of $\theta_P$ between
$-17^\circ$ and $-13^\circ$ is consistent with all the present experimental
evidence and the average $\theta_P=-15.5^\circ\pm 1.3^\circ$ seems to be
favoured. | hep-ph |
Symmetries in $B \to D^* \ell ν$ angular observables: We apply the formalism of amplitude symmetries to the angular distribution of
the decays $B \to D^* \ell \nu$ for $\ell=e,\mu,\tau$. We show that the angular
observables used to describe the distribution of this class of decays are not
independent in absence of New Physics contributing to tensor operators. We
derive sets of relations among the angular coefficients of the decay
distribution for the massless and massive lepton cases which can be used to
probe in a very general way the consistency among the angular observables and
the underlying New Physics at work. We use these relations to access the
longitudinal polarisation fraction of the $D^*$ using different angular
coefficients from the ones used by Belle experiment. This in the near future
can provide an alternative strategy to measure $F_L^{D^*}$ in $B \to D^* \tau
\nu$ and to understand the relatively high value measured by the Belle
experiment. Using the same symmetries, we identify three observables which may
exhibit a tension if the experimental value of $F_L^{D^*}$ remains high. We
discuss how these relations can be exploited for binned measurements. We also
propose a new observable that could test for specific scenarios of New Physics
generated by light right-handed neutrinos. Finally we study the prospects of
testing these relations based on the projected experimental sensitivity of new
experiments. | hep-ph |
Planar three-loop master integrals for $2 \to 2$ processes with one
external massive particle: We present analytic results for the two tennis-court integral families
relevant to $2\to2$ scattering processes involving one massive external
particle and massless propagators in terms of Goncharov polylogarithms of up to
transcendental weight six. We also present analytic results for physical
kinematics for the ladder-box family and the two tennis-court families in terms
of real-valued polylogarithmic functions, making our solutions well-suited for
phenomenological applications. | hep-ph |
Local spatial densities for composite spin-3/2 systems: The definition of local spatial densities by using sharply localized
one-particle states is applied to spin-3/2 systems. Matrix elements of the
electromagnetic current and the energy-momentum tensor are considered and
integral expressions of associated spatial distributions in terms of form
factors are derived. | hep-ph |
Neutrality of the color-flavor-locked phase in a Dyson-Schwinger
approach: The role of neutrality constraints for the phase structure of QCD at
non-vanishing chemical potentials is studied within a self-consistent
truncation scheme for the Dyson-Schwinger equation of the quark propagator in
Landau gauge. We find the (approximate) color-flavor-locked phase to be
energetically preferred at all potentially relevant densities and for physical
values of the quark masses. We furthermore observe the impossibility to define
this phase by residual global symmetries and discuss the role of chemical
potentials. | hep-ph |
Graviton-mediated dark matter model explanation the DAMPE electron
excess and search at $e^+e^-$ colliders: The very recent result of the DAMPE cosmic ray spectrum of electrons shows a
narrow bump above the background at around 1.4 TeV. We attempt to explain the
DAMPE electron excess in a simplified Kaluza-Klein graviton-mediated dark
matter model, in which the graviton only interacts with leptons and dark
matter. The related phenomenological discussions are given and this simplified
graviton-mediated dark matter model has the potential to be cross-tested in
future lepton collider experiments. | hep-ph |
Non-perturbative effects for dark sectors with QCD portals: In this work, we consider a class of dark matter (DM) models where the DM
does not directly interact with the Standard Model (SM) particles at the
tree-level. Therefore, the coannihilation mechanism is crucial in achieving the
correct DM relic abundance, which in turn requires the coannihilating partner
to be close in mass to the actual DM particle. In our systematisation of the
models' class, the mediator and the coannihilation partner are assumed to be
charged under QCD interactions. This last feature calls for a scrutiny of
non-perturbative effects, namely Sommerfeld factors and bound-state formation,
on the annihilations of the colored partner. Such non-perturbative effects are
illustrated with an example model comprising a scalar leptoquark mediator, a
Dirac vector-like fermion coannihilation partner, and a singlet DM fermion.
Phenomenological features of this model, namely DM direct and indirect
detection prospects, collider implications, and impact on the muon anomalous
magnetic moment, are discussed. | hep-ph |
Universality test of the charged Higgs boson couplings at the LHC and at
B factories: Many extensions of the Standard Model (SM) of particle physics predict the
existence of charged Higgs bosons with substantial couplings to SM particles,
which would render them observable both directly at the LHC and indirectly at
B-factories. For example, the charged Higgs boson couplings to fermions in two
doublet Higgs models of type II, are proportional to the ratio of the two Higgs
doublet vacuum expectation values (tan(beta)) and fermionic mass factors and
could thus be substantial at large tan(beta) and/or for heavy fermions. In this
work we perform a model-independent study of the charged Higgs boson couplings
at the LHC and at B-factories for large values of tan(beta). We have shown that
at high luminosity it is possible to measure the couplings of a charged Higgs
boson to the third generation of quarks up to an accuracy of 10%. We further
argue that by combining the possible measurements of the LHC and the
B-factories, it is possible to perform a universality test of charged Higgs
boson couplings to quarks. | hep-ph |
The hunt for sub-GeV dark matter at neutrino facilities: a survey of
past and present experiments: We survey the sensitivity of past and present neutrino experiments to MeV-GeV
scale dark matter, and find that these experiments possess novel sensitivity
that has not yet fully explored. NO$\nu$A and BEBC are found to rule out the
scalar thermal target for dark matter masses between 10 MeV to 100 MeV with
existing data, while CHARM-II and MINER$\nu$A place somewhat weaker limits.
These limits can be dramatically improved by off-axis searches using the NuMI
beamline and the MicroBooNE, MiniBooNE or ICARUS detectors, and can even begin
to probe the Majorana thermal target. We conclude that past and present
neutrino facilities can search for light dark matter concurrently with their
neutrino program and reach a competitive sensitivity to proposed future
experiments. | hep-ph |
Molecular states from
$Σ^{(*)}_c\bar{D}^{(*)}-Λ_c\bar{D}^{(*)}$ interaction: In this work, we systemically investigate the molecular states from the
$\Sigma^{(*)}_c\bar{D}^{(*)}-\Lambda_c\bar{D}^{(*)}$ interaction with the help
of the Lagrangians with heavy quark and chiral symmetries in a quasipotential
Bethe-Salpeter equation (qBSE) approach. The molecular states are produced from
isodoublet (I=1/2) $\Sigma_c\bar{D}$ interaction with spin parity $J^P=1/2^-$
and $\Sigma_c\bar{D}^*$ interaction with $1/2^-$ and $ 3/2^-$. Their masses and
widths are consistent with the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$
observed at LHCb. The states, $\Sigma_c^*\bar{D}^*(1/2^-)$,
$\Sigma_c^*\bar{D}^*(3/2^-)$ and $\Sigma^*_c\bar{D}(3/2^-)$, are also produced
with the same parameters. The isodoublet $\Sigma_c^*\bar{D}^*$ interaction with
$5/2^-$, as well as the isoquartet (I=3/2) $\Sigma_c\bar{D}^*$ interactions
with $1/2^-$ and $3/2^-$, $\Sigma_c^*\bar{D}^*$ interaction with $3/2^-$ and
$5/2^-$, are also attractive while very large cutoff is required to produce a
molecular state. We also investigate the origin of the widths of these
molecular states in the same qBSE frame. The $\Lambda\bar{D}^*$ channel is
dominant in the decays of the states, $\Sigma_c\bar{D}^*(1/2^-)$,
$\Sigma_c\bar{D}^*(3/2^-)$, $\Sigma_c^*\bar{D}(3/2^-)$, and
$\Sigma_c\bar{D}(1/2^-)$. The $\Sigma^*_c\bar{D}^*(1/2^-)$ state has large
coupling to $\Sigma_c\bar{D}$ channel while the $\Sigma_c\bar{D}^*$,
$\Sigma^*_c\bar{D}$ and $\Lambda_c\bar{D}^*$ channels provide similar
contributions to the width of the $\Sigma^*_c\bar{D}^*(3/2^-)$ state. These
results will be helpful to understand the current LHCb experimental results,
and the three predicted states and the decay pattern of these hidden-charmed
molecular pentaquarks can be checked in future experiments. | hep-ph |
Gravitational wave spectra from oscillon formation after inflation: We systematically investigate the preheating behavior of single field
inflation with an oscillon-supporting potential. We compute the properties of
the emitted gravitational waves (GWs) and the number density and
characteristics of the produced oscillons. By performing numerical simulations
for a variety of potential types, we divide the analyzed potentials in two
families, each of them containing potentials with varying large- or small-field
dependence. We find that the shape and amplitude of the emitted GW spectrum
have a universal feature, with the peak around the physical wavenumber $k/a
\sim m$ at the inflaton oscillation period, irrespective of the exact potential
shape. This can be used as a smoking-gun for deducing the existence of a
violent preheating phase and possible oscillon formation after inflation.
Despite this apparent universality, we find differences in the shape of the
emitted GW spectra between the two potential families, leading to
discriminating features between them. In particular, all potentials show the
emergence of a two-peak structure in the GW spectrum, arising at the time of
oscillon formation. However, potentials exhibiting efficient parametric
resonance tend to smear out this structure and by the end of the simulation the
GW spectrum exhibits a single broad peak. We further compute the properties of
the produced oscillons for each potential, finding differences in the number
density and size distribution of stable oscillons and transient overdensities.
We perform a linear fluctuation analysis and use Floquet charts to relate the
results of our simulations to the structure of parametric resonance. We find
that the growth rate of scalar perturbations and the associated oscillon
formation time are sensitive to the small-field potential shape while the
macroscopic physical properties of oscillons (e.g. total number) depend on the
large-field potential shape. | hep-ph |
Final-State Phases in $B \to D π, D^* π$, and $D ρ$ Decays: The final-state phases in $\bar{B} \to D \pi, D^* \pi$, and $D \rho$ decays
appear to follow a pattern similar to those in $D \to \bar{K} \pi$, $\bar{K}^*
\pi$, and $\bar{K} \rho$ decays. Each set of processes is characterized by
three charge states but only two independent amplitudes, so the amplitudes form
triangles in the complex plane. For the first two sets the triangles appear to
have non-zero area, while for the $D \rho$ or $\bar{K} \rho$ decays the areas
of the triangles are consistent with zero. Following an earlier discussion of
this behavior for $D$ decays, a similar analysis is performed for B decays, and
the relative phases and magnitudes of contributing amplitudes are determined.
The significance of recent results on $\ob \to D^{(*)0} \bar{K}^{(*)0}$ is
noted. Open theoretical and experimental questions are indicated. | hep-ph |
Higgs inflation in a radiative seesaw model: We investigate a simple model to explain inflation, neutrino masses and dark
matter simultaneously. This is based on the so-called radiative seesaw model
proposed by Ma in order to explain neutrino masses and dark matter by
introducing a $Z_2$-odd isospin doublet scalar field and $Z_2$-odd right-handed
neutrinos. We study the possibility that the Higgs boson as well as neutral
components of the $Z_2$-odd scalar doublet field can satisfy conditions from
slow-roll inflation and vacuum stability up to the inflation scale. We find
that a part of parameter regions where these scalar fields can play a role of
an inflaton is compatible with the current data from neutrino experiments and
those of the dark matter abundance as well as the direct search results. A
phenomenological consequence of this scenario results in a specific mass
spectrum of scalar bosons, which can be tested at the LHC, the International
Linear Collider and the Compact Linear Collider. | hep-ph |
On power corrections to event shapes: Recent work on the theme of power corrections in perturbative QCD is briefly
reviewed, with an emphasis on event shapes in e+ e- annihilation. The
factorization of soft gluon effects is the main tool: it leads to resummation,
and thus highlights the limitations of perturbation theory, pointing to
nonperturbative corrections whose size can be estimated. Power corrections can
be resummed into shape functions, for which QCD--based models are available.
Theoretical progress is closing in on the nonperturbative frontier. | hep-ph |
Low-energy meson phenomenology with Resonance Chiral Lagrangians: The low energy behaviour of Quantum Chromodynamics makes unreliable an
expansion in terms of its coupling strength, since nothing guarantees the
convergence of such expansion. To overcomer such difficulty one resorts to
Lattice QCD or Effective Field Theories. In this thesis we compute hadronic
processes at low energies, using Resonance Chiral Lagrangians as the effective
theory of QCD. The processes we study are important background on the search
for Lepton Flavor Violation, Lepton Universality Violation, Lepton Number
Violation, Second Class Currents and study the Hadronic light-by-light
contribution to the Anomalous Magnetic Moment of the muon. All such processes
are of great interest since all of them are to be studied with an increased
precision in the very near future by different experiments. | hep-ph |
Improved bounds on non-luminous matter in solar orbit: We improve, using a larger set of observations including Voyager 2 Neptune
flyby data, previous bounds on the amount of dark matter (DM) trapped in a
spherically symmetric distribution about the sun. We bound DM by noting that
such a distribution would increase the effective mass of the sun as seen by the
outer planets and by finding the uncertainty in that effective mass for Uranus
and Neptune in fits to the JPL Developmental Ephermeris residuals, including
optical data and those two planets' Voyager 2 flybys. We extend our previous
procedure by fitting more parameters of the developmental ephemerides.
Additionally, we present here the values for Pioneer 10 and 11 and Voyager 1
and 2 Jupiter ranging normal points (and incorporate these data as well). Our
principal result is to limit DM in spherically symmetric distributions in orbit
about the sun interior to Neptune's orbit to less than an earth mass and
interior to Uranus' orbit to about 1/6 of an earth's mass. | hep-ph |
Third-order non-Coulomb correction to the S-wave quarkonium wave
functions at the origin: We compute the third-order correction to the S-wave quarkonium wave functions
|\psi_n(0)|^2 at the origin from non-Coulomb potentials in the effective
non-relativistic Lagrangian. Together with previous results on the Coulomb
correction and the ultrasoft correction computed in a companion paper, this
completes the third-order calculation up to a few unknown matching
coefficients. Numerical estimates of the new correction for bottomonium and
toponium are given. | hep-ph |
Consistent Scenarios for Cosmic-Ray Excesses from Sommerfeld-Enhanced
Dark Matter Annihilation: Anomalies in direct and indirect detection have motivated models of dark
matter consisting of a multiplet of nearly-degenerate states, coupled by a new
GeV-scale interaction. We perform a careful analysis of the thermal freezeout
of dark matter annihilation in such a scenario. We compute the range of "boost
factors" arising from Sommerfeld enhancement in the local halo for models which
produce the correct relic density, and show the effect of including constraints
on the saturated enhancement from the cosmic microwave background (CMB). We
find that boost factors from Sommerfeld enhancement of up to ~800 are possible
in the local halo. When the CMB bounds on the saturated enhancement are
applied, the maximal boost factor is reduced to ~400 for 1-2 TeV dark matter
and sub-GeV force carriers, but remains large enough to explain the observed
Fermi and PAMELA electronic signals. We describe regions in the DM mass-boost
factor plane where the cosmic ray data is well fit for a range of final states,
and show that Sommerfeld enhancement alone is enough to provide the large
annihilation cross sections required to fit the data, although for light
mediator masses (less than ~200 MeV) there is tension with the CMB constraints
in the absence of astrophysical boost factors from substructure. Additionally,
we consider the circumstances under which WIMPonium formation is relevant and
find for heavy WIMPs (greater than ~2 TeV) and soft-spectrum annihilation
channels it can be an important consideration; we find regions with dark matter
mass greater than 2.8 TeV that are consistent with the CMB bounds and have
~600-700 present-day boost factors. | hep-ph |
CP Violation in the B System: Strategies for extracting CKM phases from non-leptonic $B$ decays are
reviewed briefly. Both general aspects and some recent developments including
CP-violating asymmetries, the $B_s$ system in light of a possible width
difference $\Delta\Gamma_s$, and triangle relations among $B$ decay amplitudes
are discussed. The role of electroweak penguins in these strategies is
illustrated briefly. | hep-ph |
Tracking down hyper-boosted top quarks: The identification of hadronically decaying heavy states, such as vector
bosons, the Higgs, or the top quark, produced with large transverse boosts has
been and will continue to be a central focus of the jet physics program at the
Large Hadron Collider (LHC). At a future hadron collider working at an
order-of-magnitude larger energy than the LHC, these heavy states would be
easily produced with transverse boosts of several TeV. At these energies, their
decay products will be separated by angular scales comparable to individual
calorimeter cells, making the current jet substructure identification
techniques for hadronic decay modes not directly employable. In addition, at
the high energy and luminosity projected at a future hadron collider, there
will be numerous sources for contamination including initial- and final-state
radiation, underlying event, or pile-up which must be mitigated. We propose a
simple strategy to tag such "hyper-boosted" objects that defines jets with
radii that scale inversely proportional to their transverse boost and combines
the standard calorimetric information with charged track-based observables. By
means of a fast detector simulation, we apply it to top quark identification
and demonstrate that our method efficiently discriminates hadronically decaying
top quarks from light QCD jets up to transverse boosts of 20 TeV. Our results
open the way to tagging heavy objects with energies in the multi-TeV range at
present and future hadron colliders. | hep-ph |
Some tests for the helicity structure of the pomeron in $ep$ collisions: We discuss the reaction $e p \to e \tilde{p} X$ in the one-photon exchange
approximation, where it is in essence the reaction $\gamma^{*} p \to \tilde{p}
X$. A large rapidity gap is required between the particle or particles of the
proton remnant $\tilde{p}$ and those of $X$. We define a suitable azimuthal
angle $\varphi$ between a leptonic and a hadronic plane. The dependence of the
cross section on $\varphi$ is given explicitly and can be used to extract cross
sections and interference terms for the reaction $\gamma^{*} p \to \tilde{p} X$
corresponding to the various helicities of the virtual photon $\gamma^{*}$. The
interference terms can be used to test models for the large rapidity gap events
in a sensitive way. We discuss in detail models with factorizing Pomeron
exchange and in particular the Donnachie-Landshoff Pomeron model. We make some
remarks on soft colour exchange models and on possible effects of QCD
background vacuum fields. We conclude with a suggestion to look for Odderon
exchange in exclusive deep inelastic high energy reactions like $\gamma^{*} p
\to \tilde{p} \pi^{0}$ and $\gamma^{*} p \to \tilde{p} \eta$. | hep-ph |
Simple and robust method for search Dark Matter particles and measuring
their properties at ILC in various models of DM: I suggest simple method for the search of Dark Matter particles and some
related particles which allows to measure reliably their mass and spin in a
wide class of models for Dark Matter. | hep-ph |
Axion and Right-handed Neutrino in the Minimal SUSY SO(10) Model: The connection between the axion and right-handed neutrinos is explored in
the framework of the minimal SUSY SO(10) model. The former is related to the
Peccei-Quinn (PQ) solution to the strong CP problem and the latter is to the
light Majorana neutrinos through the see-saw mechanism. In this model, a
relative phase between $({\bf 10,1,3}) (\equiv {\bf \bar{\Delta}}_R) \subset
{\bf \bar{126}}$ and $({\bf \bar{10},1,3}) (\equiv {\bf \Delta}_R) \subset {\bf
126}$ multiplets of ${\rm SU}(4) \times {\rm SU}(2)_L \times {\rm SU}(2)_R
\subset {\rm SO}(10)$ becomes a physical degree of freedom identified with the
axion. Then, the PQ symmetry breaking scale ($\Lambda_{\rm PQ}$) and the $B-L$
symmetry breaking scale ($\Lambda_{\rm B-L}$) coincide through the VEV of ${\bf
\bar{\Delta}}_R$. The scalar partner of the lightest right-handed neutrino is
regarded as the inflaton, which gives a consistent density fluctuation for the
CMB. | hep-ph |
Dark matter stability from non-Abelian discrete flavor symmetries: We present a mechanism for the dark matter stability in the framework of a
non-Abelian avour symmetry renormalizable model. The same non-abelian discrete
avor symmetry which accounts for the observed pattern of neutrino oscillations,
spontaneously breaks to a Z2 subgroup which renders DM stable. The simplest
scheme leads to a scalar doublet DM potentially detectable in nuclear recoil
experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta
decay rate accessible to upcoming searches. | hep-ph |
Empirical Parameterization of Nucleon-Nucleon Elastic Scattering
Amplitude at High Beam Momenta for Glauber Calculations and Monte Carlo
Simulations: A parameterization of the nucleon-nucleon elastic scattering amplitude is
needed for future experiments with nucleon and nuclear beams in the beam
momentum range of 2 -- 50 GeV/c/nucleon. There are many parameterizations of
the amplitude at $P_{lab} >$ 25--50 GeV/c, and at $P_{lab} \leq$ 5 GeV/c. Our
paper is aimed to cover the range between 5 -- 50 GeV/c.
The amplitude is used in Glauber calculations of various cross sections and
Monte Carlo simulations of nucleon-nucleon scatterings. Usually, the
differential nucleon-nucleon elastic scattering cross sections are described by
an exponential expression. Corresponding experimental data on $pp$ interactions
at $|t|>$ 0.005 (GeV/c)$^2$ and $|t|\leq$ 0.125 (GeV/c)$^2$ have been fit. We
propose formulae to approximate the beam momentum dependence of these
parameters in the momentum range considered. The same was done for $np$
interactions at $|t|\leq$ 0.5 (GeV/c)$^2$. Expressions for the momentum
dependence of the total and elastic cross sections, and the ratio of real to
imaginary parts of the amplitude at zero momentum transfer are also given for
$pp$ and $np$ collisions. These results are sufficient for a first
approximation of the Glauber calculations. For more exact calculations we fit
the data at $|t|>$ 0.005 (GeV/c)$^2$ without restrictions on the maximum value
of $|t|$ using an expression based on two coherent exponential. The parameters
of the fits are found for the beam momentum range 2 -- 50 GeV/c. | hep-ph |
Can the Super-Kamiokande Atmospheric Data Predict the Solar Neutrino
Deficit ?: In this Letter we show that the evidence for neutrino oscillations from the
Super-Kamiokande atmospheric neutrino data fully determines the 3x3
neutrino-oscillations mixing matrix and predicts an energy independent solar
neutrino deficit at the level of 45%. This corresponds to a ratio of measured
to predicted neutrino flux of R_e^{Solar} = 0.55, in good agreement with the
experimental results. We achieve this result within the framework of a minimal,
three-generations neutrino mixing, with mass squared differences of dM^2 = 0.45
eV^2 and dm^2 = O(10^-3) eV^2. The mixing matrix derived here is characterized
by the mixing angles theta = 35.1, beta = 5.5, and psi = 23.3, and a vanishing
CP-violating phase, delta = 0. | hep-ph |
Evolution of gluon TMDs from small to moderate x: Recently we obtained an evolution equation of gluon TMDs, which addresses a
problem of unification of different kinematic regimes. It describes evolution
in the whole range of Bjorken $x_B$ and the whole range of transverse momentum
$k_\perp$. In this notes I study different limits of this evolution equation
and show how it yields several well-known and some previously unknown results. | hep-ph |
Reconstructing events with missing transverse momentum at the LHC and
its application to spin measurement: In this article we discuss the measurement of spin at the LHC, in events with
two unknown four-momenta. Central to this problem is the identification of
spin-dependent kinematic variables and the construction of a statistical test
that can distinguish between different spin hypotheses. We propose a method for
reconstructing kinematic variables that depend upon the unknown momenta. The
method is based upon a probabilistic reconstruction of each event, given the
masses of the final and intermediate states and the cross-section of the
assumed hypothesis. We demonstrate that this method can distinguish between two
spin hypotheses for a specific process, even after mass uncertainties and
Standard Model backgrounds are taken into account. We compare our method with
another that only utilises the observable momenta of each event. We will show
that our method permits an improved discrimination between hypotheses, with a
reduced probability of error. | hep-ph |
Probing New Physics with $\bar B \to ρ(770) \, \ell^- \bar ν_\ell$
and $\bar B \to a_1(1260) \, \ell^- \bar ν_\ell$: The $B$ meson semileptonic modes to $\rho(770)$ and $a_1 (1260)$ are useful
to pin down possible non Standard Model effects. The 4d differential $\bar B
\to \rho(\pi \pi) \ell^- \bar \nu_\ell$ and $ \bar B \to a_1 (\rho \pi) \ell^-
\bar \nu_\ell$ decay distributions are computed in SM and in extensions
involving new Lepton Flavour Universality violating semileptonic $b \to u$
operators. The Large Energy limit for the light meson is also considered for
both modes. The new effective couplings are constrained using the available
data, and several observables in $\bar B \to \rho(\pi\pi) \ell^- \bar \nu_\ell$
in which NP effects can be better identified are selected, using the angular
coefficient functions. The complementary role of $\bar B \to \rho(\pi \pi)
\ell^- \bar \nu_\ell$ and $\bar B \to a_1 (\rho \pi) \ell^- \bar \nu_\ell$ is
discussed. | hep-ph |
Dark Matter Phenomenology: I review recent developments in the direct and indirect detection of dark
matter and new candidates beyond the WIMP paradigm. | hep-ph |
Extra $Z^\prime$s and $W^\prime$s in Heterotic--String Derived Models: The ATLAS collaboration recently recorded possible excess in the di--boson
production at the di--boson invariant mass at around 2 TeV. Such an excess may
be produced if there exist additional $Z^\prime$ and/or $W^\prime$ at that
scale. We survey the extra $Z^\prime$s and $W^\prime$s that may arise from
semi--realistic heterotic string vacua in the free fermionic formulation in
seven distinct cases including: $U(1)_{Z^\prime}\in SO(10)$; family universal
$U(1)_{Z^\prime}$ not in $SO(10)$; non--universal $U(1)_{Z^\prime}$; hidden
sector $U(1)$ symmetries and kinetic mixing; left--right symmetric models;
Pati--Salam models; leptophobic and custodial symmetries. Each case has a
distinct signature associated with the extra symmetry breaking scale. In one of
the cases we explore the discovery potential at the LHC using resonant
leptoproduction. Existence of extra vector boson with the reported properties
will significantly constrain the space of allowed string vacua. | hep-ph |
The evolution of parton distributions beyond leading order: the singlet
case: A complete description of the calculation of anomalous dimensions (GLAP
splitting functions) is given for parton distributions which appear in
space-like processes. The calculation is performed in the light-cone gauge. The
results are in agreement with the previous results of Furmanski and Petronzio. | hep-ph |
The AdS/CFT Correspondence and Light-Front QCD: We identify an invariant light-front coordinate $\zeta$ which allows the
separation of the dynamics of quark and gluon binding from the kinematics of
constituent spin and internal orbital angular momentum. The result is a
single-variable light-front Schrodinger equation for QCD which determines the
eigenspectrum and the light-front wavefunctions of hadrons for general spin and
orbital angular momentum. This frame-independent light-front wave equation is
equivalent to the equations of motion which describe the propagation of
spin-$J$ modes on anti-de Sitter (AdS) space. Light-front holography is a
remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth
dimension to be mapped to frame-independent light-front wavefunctions of
hadrons in physical space-time, thus providing a relativistic description of
hadrons at the amplitude level. In principle, the model can be systematically
improved by diagonalizing the full QCD light-front Hamiltonian on the AdS/QCD
basis. Quark and gluon hadronization can be computed at the amplitude level by
convoluting the off-shell $T$ matrix calculated from the QCD light-front
Hamiltonian with the hadronic light-front wavefunctions. We also note the
distinction between static observables such as the probability distributions
computed from the square of the light-front wavefunctions versus dynamical
observables such as the structure functions and the leading-twist single-spin
asymmetries measured in deep inelastic scattering which include the effects of
initial and final-state interactions. | hep-ph |
Mass Measurement in Boosted Decay Chains with Missing Energy: We explore a novel method of mass reconstruction in events with missing
transverse momentum at hadron colliders. In events with sizeable boost factors
in the final steps of dual multi-stage decay chains, the missing energy
particles may each be approximately collinear with a visible standard model
particle, spanning a narrow "MET-cone." We exploit this collinear
approximation, when applicable, to reconstruct the masses of exotica. | hep-ph |
Infrared Effects of Ultraviolet Operators on Dark Matter Freeze-In: Dark matter (DM) that interacts too weakly with the Standard Model (SM) to
reach full thermodynamic equilibrium can be still be created in significant
amounts by rare SM collisions. This mechanism, called freeze-in, can proceed
through a renormalizable connector operator with a very small coefficient, or a
non-renormalizable connector operator suppressed by a large mass scale. In the
latter non-renormalizable scenario, the dominant creation of DM particles
typically occurs at the largest SM temperature attained during the radiation
era (assuming a standard cosmological history), and for this reason it is
referred to as ultraviolet freeze-in. We show that non-renormalizable operators
can also contribute importantly to the DM density at lower temperatures down to
below the mass of the DM particle. To do so, we compute the production,
annihilation, and freeze-out of DM in a simple dark sector consisting of a
massive Dirac fermion DM candidate coupled to a massless Abelian vector boson
with the only connection to the SM through the fermionic Higgs portal operator.
For a broad range of parameters in the theory, the dark sector is populated by
ultraviolet freeze-in in the usual way, self-thermalizes to a dark temperature
below that of the SM, and undergoes thermal freeze-out. We show that late
residual freeze-in reactions during the freeze-out process can further populate
the dark sector and increase the DM relic density beyond standard dark sector
freeze-out. | hep-ph |
Gravitational Lensing and Extra Dimensions: We study gravitational lensing and the bending of light in low energy scale
(M_S) gravity theories with extra space-time dimensions n. We find that due to
the presence of spin-2 Kaluza-Klein states from compactification, a correction
to the deflection angle with a strong quadratic dependence on the photon energy
is introduced. No deviation from the Einstein General Relativity prediction for
the deflection angle for photons grazing the Sun in the visible band with 15%
accuracy (90% c.l.) implies that the scale M_S has to be larger than
1.4(2/(n-2))^{1/4} TeV and approximately 4 TeV for n=2. This lower bound is
comparable with that from collider physics constraints. Gravitational lensing
experiments with higher energy photons can provide stronger constraints. | hep-ph |
epsilon'/epsilon and Chiral Dynamics: The long-distance contributions to $K\to 2\pi$ amplitudes can be pinned down,
using well established Chiral Perturbation Theory techniques. The strong
S--wave rescattering of the two final pions generates sizeable chiral loop
corrections, which have an important impact on the direct CP violation ratio
epsilon'/epsilon. Including all large logarithmic corrections, both at short
and long distances, the Standard Model Prediction for this observable is found
to be Re(epsilon'/epsilon) = (1.7\pm 0.9) 10^{-3}, in good agreement with the
most recent experimental measurements. A better estimate of the strange quark
mass could reduce the theoretical uncertainty to 30%. | hep-ph |
$B{\bar B}$ angular correlations at the LHC in parton Reggeization
approach merged with higher-order matrix elements: We calculate the angular distribution spectra between beauty ($B$) and
anti-beauty ($\bar B$) mesons in proton-proton collisions in the leading order
approximation of the parton Reggeization approach consistently merged with the
next-to-leading order corrections from the emission of additional hard gluon.
To describe b-quark hadronization we use the universal scale-depended
parton-to-meson fragmentation functions extracted from the world $e^+e^-$
annihilation data. We have obtained good agreement between our predictions and
data from the CMS Collaboration at the energy $\sqrt{S}=7$ TeV for $B \bar B$
angular correlations within uncertainties and without free parameters.
Predictions for analogous correlation observables at $\sqrt{S}=13$ TeV are
provided. | hep-ph |
Coherent States in High-Energy Physics: The amplitude for emitting $n$ bosons factorizes into the product of $n$
single-boson emission amplitudes, if the source is energetic and abelian. If it
is energetic but {\it non-abelian}, the amplitude is given by a sum of
factorized {\it quasi-particle} amplitudes. A quasi-particle is made up of an
arbitrary number of bosons, but couples to the source like a single one.
Factorization is related to coherence, and it allows computation of subleading
contributions not obtainable by usual means. Its importance is illustrated in
two applications: to solve the baryon problem in large-$N_c$ QCD, and to obtain
a total cross section satisfying the Froissart bound. | hep-ph |
Nucleon-Nucleon Interaction and Isospin Violation: The application of the chiral effective theory to processes with two or more
nucleons is discussed. We gain a qualitative understanding of the gross
features of nuclear physics and quantitative, testable postdictions and
predictions involving photons and pions. | hep-ph |
Neutrino's Non-Standard Interactions; Another Eel under a Willow?: I report some progress that occurred since NO-VE08 in the field of
non-standard interactions (NSI) of neutrinos. After briefly reviewing
theoretical developments, I give a summary of the two works in which I was
involved. Firstly, we have formulated a perturbative framework to illuminate
the global features of neutrino oscillations with NSI, aiming at exploring
method for determination of the standard mixing and the NSI parameters. We have
recognized that the parameter degeneracy prevails with an extended form which
involves the NSI elements. Furthermore, a completely new type of degeneracy is
shown to exist. The nature of the former degeneracy is analyzed in detail in
the second work. The work is primarily devoted to analyze the problem of
discriminating the two CP violation, one due to the lepton Kobayashi-Maskawa
phase and the other by phases of the NSI elements. We have shown that the near
(3000 km)-far (7000 km) two detector setting in neutrino factory does have the
discrimination capability and is sensitivities to CP violation due to NSI to
|epsilon_{e\mu}| to \simeq several x 10^{-4} in most of the region of \delta
and \phi. | hep-ph |
More Energy, More Searches, but the pMSSM Lives On: We further examine the capability of the 7 and 8 TeV LHC to explore the
parameter space of the p(henomenological)MSSM with neutralino LSPs. Here we
present an updated study employing all of the relevant ATLAS SUSY analyses, as
well as all relevant LHC non-MET searches, whose data were publically available
as of mid-September 2012. We find that roughly 1/3 of our pMSSM model points
are excluded at present with an important role being played by both the heavy
flavor and multi-lepton searches, as well as those for heavy stable charged
particles. Nonetheless, we find that light gluinos, 1st/2nd generation squarks,
and stop/sbottoms (\lsim 400-700 GeV), as well as models with 1% fine-tuning or
better, are still viable in the pMSSM. In addition, we see that increased
luminosity at 8 TeV is unlikely to significantly improve the reach of the
"vanilla" searches. The impact of these null searches on the SUSY sparticle
spectrum is discussed in detail and the implications of these results for
models with low fine-tuning, a future lepton collider and dark matter searches
are examined. | hep-ph |
Quantum Mechanics with Neutral Kaons: We briefly illustrate a few tests of quantum mechanics which can be performed
with entangled neutral kaon pairs at a Phi-factory. This includes a
quantitative formulation of Bohr's complementarity principle, the quantum
eraser phenomenon and various forms of Bell inequalities. | hep-ph |
Effect of CP violation in the singlet-doublet dark matter model: We revisit the singlet-doublet dark matter model with a special emphasis on
the effect of CP violation on the dark matter phenomenology. The CP violation
in the dark sector induces a pseudoscalar interaction of a fermionic dark
matter candidate with the SM Higgs boson. The pseudoscalar interaction helps
the dark matter candidate evade the strong constraints from the dark matter
direct detection experiments. We show that the model can explain the measured
value of the dark matter density even if dark matter direct detection
experiments do not observe any signal. We also show that the electron electric
dipole moment is an important complement to the direct detection for testing
this model. Its value is smaller than the current upper bound but within the
reach of future experiments. | hep-ph |
Measuring C-odd correlations at lepton-proton and photon-proton
collisions: We consider the charge-odd correlations (COC) in cross sections of processes
of production of charged particles. The cases of a muonic pair and pion systems
$\pi^{+}\pi^{-},\pi^{+}\pi^{-}\pi^{0}$ are considered in detail for
electron-proton or photon-proton collisions in the proton fragmentation region
kinematics. COC arise from interference of amplitudes which describe the
different mechanisms of charged leptons (pions) creation. One of them
corresponds to production of particles in the charge-odd state (one virtual
photon or vector meson annihilation to this system of particles) and the other
corresponds to the charge-even state of produced particles (creation by two
photons). COC for muon-antimuon pair creation have a pure QED nature and can be
considered as a normalization process. The processes with pion production are
sensitive to some characteristics of proton wave functions and, besides, can be
used for checking the anomalous and normal parts of the effective pionic
lagrangian.
Three electromagnetic currents operator matrix element can be measured in
photon-proton interactions with lepton pair production. For this aim a
charge-odd combination of cross sections can be constructed as a conversion of
leptonic 3-rank tensor with hadronic ones. These experiments can be considered
as an alternative to deep virtual Compton scattering. | hep-ph |
Cosmological Phase Transition of Spontaneous Confinement: The dynamics of a cosmological (de)confinement phase transition is studied in
nearly conformally invariant field theories, where confinement is predominantly
spontaneously generated and associated with a light "dilaton" field. We show
how the leading contribution to the transition rate can be computed within the
dilaton effective theory. In the context of Composite Higgs theories, we
demonstrate that a simple scenario involving two renormalization-group fixed
points can make the transition proceed much more rapidly than in the minimal
scenario, thereby avoiding excessive dilution of matter abundances generated
before the transition. The implications for gravitational wave phenomenology
are discussed. In general, we find that more (less) rapid phase transitions are
associated with weaker (stronger) gravitational wave signals. The various
possible features of the strongly coupled composite Higgs phase transition
discussed here can be concretely modeled at weak coupling within the AdS/CFT
dual Randall-Sundrum extra-dimensional description, which offers important
insights into the nature of the transition and its theoretical control. These
aspects will be presented in a companion paper. | hep-ph |
Division algebraic symmetry breaking: Reframing certain well-known particle models in terms of normed division
algebras leads to two new results for BSM physics.
(1) We identify a sequence of complex structures which induces a cascade of
breaking symmetries: Spin(10) $\mapsto$ Pati-Salam $\mapsto$ Left-Right
symmetric $\mapsto$ Standard model + B-L (both pre- and post-Higgs-mechanism).
These complex structures derive from the octonions, then from the quaternions,
then from the complex numbers.
(2) We provide, also for the first time we believe, an explicit demonstration
of left-right symmetric Higgs representations stemming from quaternionic
triality, tri($\mathbb{H}$). Upon the breaking of $su(2)_R$, our Higgs reduces
to the familiar standard model Higgs. | hep-ph |
On the Character of Leading Asymmetry in the Hadroproduction of Charmed
Mesons and Baryons: The character of asymmetry between the spectra of Lambda_c and antiLambda_c
in the E781 experiment (FNAL) is discussed on the basis of the Quark Gluon
String Model(QGSM). As it was shown in the description of the asymmetry between
the spectra of leading and nonleading charmed mesons measured in Sigma^--A
interactions at p_L= 340 GeV/c in the WA89 experiment in previous studies, the
asymmetries between D^- and D^+ meson spectra and between D_s^- and D^+_s meson
spectra can be fitted by QGSM curves with the same parameter of string
fragmentation, a_1=10, as well as the asymmetry between the D-meson spectra in
pion-nuclear collisions in the E791 experiment. The forms of
Lambda_c/antiLambda_c asymmetry dependences measured in Sigma^-A and p-A
collisions at p_L= 600 GeV/c in the E781 experiment are different . It is shown
in the framework of QGSM that they depend on whether the diquarks of beam and
target particles took part in charmed baryon formation or not. The QGSM results
are compared with the calculations carried out by the other authors. | hep-ph |
QCD corrections to longitudinal spin asymmetries in $W^\pm$-boson
production at RHIC: The polarized antiquark distributions in the proton can be measured by
studying spin asymmetries in vector boson production in longitudinally
polarized proton-proton collisions. The STAR and PHENIX experiments at BNL RHIC
have reported first observations of single spin asymmetries in
$W^\pm$-production most recently. We compute the QCD corrections to single and
double spin asymmetries, taking account of the leptonic decay of the $W^\pm$
boson and of restrictions on the kinematical acceptance of the detectors. The
QCD corrections have only a small impact on the asymmetries, such that a
reliable extraction of the polarized antiquark distributions can be envisaged
once more precise measurements are made. | hep-ph |
Pion structure function at small x from DIS data: Production of leading neutrons in DIS is usually considered as a tool to
measure the pion structure function at small x accessible at HERA. The main
obstacle is the lack of reliable evaluations of the absorption corrections,
which significantly suppress the cross section. We performed a parameter free
calculation within the dipole approach and found the absorption corrections to
be nearly as strong, as for neutron production in pp collisions. We also
included the significant contribution of the iso-vector Reggeons with natural
(\rho, a_2) and unnatural (a_1, \rho-\pi\ cut) parity with parameters
constrained by phenomenology. With a certain modeling for the pion-to-proton
ratio of the structure functions we reached good agreement with data from the
ZEUS and H1 experiments, successfully reproducing the observed dependence on
the fractional neutron momentum z, the photon virtuality Q^2, and the
transverse momentum transfer q_T. | hep-ph |
SU(3) Chiral Dynamics with Coupled Channels: Eta and Kaon
Photoproduction: We identify the leading s-wave amplitudes of the SU(3) chiral meson-baryon
Lagrangian with an effective coupled-channel potential which is iterated in a
Lippmann-Schwinger equation. The strangeness $S=-1$ resonance $\Lambda(1405)$
and the $S_{11}(1535)$ nucleon resonance emerge as quasi-bound states of
anti-kaon/nucleon and kaon/$\Sigma$-hyperon. Our approach to meson
photoproduction introduces no new parameters. By adjusting a few finite range
parameters we are able to simultaneously describe a large amount of low energy
data. These include the cross sections of $K^-p$ elastic and inelastic
scattering, the cross sections of eta meson and kaon photoproduction from
nucleons as well as those of pion induced production of etas and kaons (16
different reaction channels altogether). | hep-ph |
Meson loop effect on high density chiral phase transition: We test the stability of the mean-field solution in the Nambu--Jona-Lasinio
model. For stable solutions with respect to both the \sigma and \pi directions,
we investigate effects of the mesonic loop corrections of 1/N_c, which
correspond to the next-to-leading order in the 1/N_c expansion, on the high
density chiral phase transition. The corrections weaken the first order phase
transition and shift the critical chemical potential to a lower value. At
N_c=3, however, instability of the mean field effective potential prevents us
from determining the minimum of the corrected one. | hep-ph |
Study of $Λ_b\to Λ(φ,η^{(\prime)})$ and $Λ_b\to
ΛK^+K^-$ decays: We study the charmless two-body $\Lambda_b\to \Lambda (\phi,\eta^{(\prime)})$
and three-body $\Lambda_b\to \Lambda K^+K^- $ decays. We obtain ${\cal
B}(\Lambda_b\to \Lambda\phi)=(3.53\pm 0.24)\times 10^{-6}$ to agree with the
recent LHCb measurement. However, we find that ${\cal B}(\Lambda_b\to
\Lambda(\phi\to)K^+ K^-)=(1.71\pm 0.12)\times 10^{-6}$ is unable to explain the
LHCb observation of ${\cal B}(\Lambda_b\to\Lambda K^+ K^-)=(15.9\pm 1.2\pm
1.2\pm 2.0)\times 10^{-6}$, which implies the possibility for other
contributions, such as that from the resonant $\Lambda_b\to K^-
N^*,\,N^*\to\Lambda K^+$ decay with $N^*$ as a higher-wave baryon state. For
$\Lambda_b\to \Lambda \eta^{(\prime)}$, we show that ${\cal B}(\Lambda_b\to
\Lambda\eta,\,\Lambda\eta^\prime)= (1.47\pm 0.35,1.83\pm 0.58)\times 10^{-6}$,
which are consistent with the current data of $(9.3^{+7.3}_{-5.3},<3.1)\times
10^{-6}$, respectively. Our results also support the relation of ${\cal
B}(\Lambda_b\to \Lambda\eta) \simeq {\cal B}(\Lambda_b\to\Lambda\eta^\prime)$,
given by the previous study. | hep-ph |
Note on Custodial Symmetry in the Two-Higgs-Doublet Model: We present a simple and transparent method to study custodial symmetry in the
Two-Higgs-Doublet Model. The method allows to formulate the basis independent,
sufficient and necessary, conditions for the custodial symmetry of the scalar
potential. The relation between the custodial transformation and CP is
discussed and clarified. | hep-ph |
A Remark on A Remark on Neutrino Oscillations Observed in KamLAND
Experiment: It is shown that equal magnitudes of the transitions $\bar \nu_e \to \bar
\nu_{\mu}$ and $\bar \nu_e \to \bar \nu_{\tau}$ in the disappearance of reactor
$\bar \nu_e$ discovered in the KamLAND experiment just follows at
$\theta_{23}=\pi/4$ and $\theta_{13}=0$ from pure symmetry of $\nu_{\mu}$ and
$\nu_{\tau}$ states relatively the mass states. | hep-ph |
Curvature-Restored Gauge Invariance and Ultraviolet Naturalness: It is shown that, $(a \Lambda^2 + b |H|^2)R$ in a spacetime of curvature $R$
is a natural ultraviolet $(U\!V)$ completion of $(a \Lambda^4 + b \Lambda^2
|H|^2)$ in the flat-spacetime Standard Model $(S\!M)$ with Higgs field $H$,
$U\!V$ scale $\Lambda$ and loop factors $a$, $b$. This curvature completion
rests on the fact that a $\Lambda$-mass gauge theory in flat spacetime turns,
on the cut-view $R = 4 \Lambda^2$, into a massless gauge theory in curved
spacetime. It provides a symmetry reason for curved spacetime, wherein gravity
and matter are both low-energy effective phenomena. Gravity arises correctly if
new physics exists with at least 63 more bosons than fermions, with no need to
interact with the $S\!M$ and with dark matter as a natural harbinger. It can
source various cosmological, astrophysical and collider phenomena depending on
its spectrum and couplings to the $S\!M$. | hep-ph |
Spontaneous Symmetry Breaking and Chiral Symmetry: In this introductory lecture, some basic features of the spontaneous symmetry
breaking are discussed. More specifically, $\sigma $-model, non-linear
realization, and some examples of spontaneous symmetry breaking in the
non-relativistic system are discussed in details. The approach here is more
pedagogical than rigorous and the purpose is to get some simple explanation of
some useful topics in this rather wide area. . | hep-ph |
Deconstructing 5-D QED: We discuss periodic compactification and latticization of a 5-D U(1) theory
with a Dirac fermion, yielding a 1+3 effective theory. We address subtleties in
the lattice fermionic action,such as fermion doubling and the Wilson term. We
compute the Coleman-Weinberg potential for the Wilson line which is finite for
N-branes >= 3, due to the Z_N symmetry, which replaces translations in the 5th
dimension. This mode becomes a PNGB in the low energy 1+3 theory. We derive its
anomalous coupling to the "photon" and its KK-modes. | hep-ph |
Role of beam polarization in the determination of $WWγ$ and $WWZ$
couplings from $e^+e^-\to W^+W^-$: We evaluate the constraints on anomalous trilinear gauge-boson couplings that
can be obtained from the study of electron-positron annihilation into $W$ pairs
at a facility with either the electron beam longitudinally polarized or both
electron and positron beams transversely polarized. The energy ranges
considered in the analysis are the ones relevant to the next-linear collider
and to LEP~200. We discuss the possibilities of a model independent analysis of
the general $CP$ conserving anomalous effective Lagrangian, as well as its
restriction to some specific models with reduced number of independent
couplings. The combination of observables with initial and final state
polarizations allows to separately constrain the different couplings and to
improve the corresponding numerical bounds. | hep-ph |
Heavy quarks at RHIC and LHC within a partonic transport model: Production and space-time evolution of heavy quarks in central and
non-central heavy-ion collisions at RHIC and LHC are studied with the partonic
transport model Boltzmann Approach of MultiParton Scatterings (BAMPS). In
addition to the initially created heavy quarks in hard parton scatterings
during nucleon-nucleon collisions, secondary heavy quark production in the
quark-gluon plasma is investigated and the sensitivity on various parameters is
estimated. In BAMPS heavy quarks scatter with particles of the medium via
elastic collisions, whose cross section is calculated with the running coupling
and a more precise implementation of Debye screening. In this framework, we
compute the elliptic flow and nuclear modification factor of heavy quarks and
compare it to the experimental data. | hep-ph |
CMB imprints of high scale non-thermal leptogenesis: We study the imprints of high scale non-thermal leptogenesis on cosmic
microwave background (CMB) from the measurements of inflationary spectral index
($n_s$) and tensor-to-scalar ratio ($r$), which otherwise is inaccessible to
the conventional laboratory experiments. We argue that non-thermal production
of baryon (lepton) asymmetry from subsequent decays of inflaton to heavy
right-handed neutrinos (RHN) and RHN to SM leptons is sensitive to the
reheating dynamics in the early Universe after the end of inflation. Such
dependence provides detectable imprints on the $n_s-r$ plane which is well
constrained by the Planck experiment. We investigate two separate cases, (I)
inflaton decays to radiation dominantly and (II) inflaton decays to RHN
dominantly which further decays to the SM particles to reheat the Universe
adequately. Considering a class of $\alpha-$ attractor inflation models, we
obtain the allowed mass ranges for RHN for both cases and thereafter furnish
the estimates for $n_s$ and $r$. The prescription proposed here is general and
can be implemented in various kinds of single-field inflationary models given
the conditions for non-thermal leptogenesis are satisfied. | hep-ph |
Probing Charged Higgs Bosons in the 2-Higgs Doublet Model Type-II with
Vector-Like Quarks: We study the phenomenology of charged Higgs bosons ($H^\pm$) and Vector-Like
Quarks (VLQs), denoted as $T$, the latter possessing a charge identical to the
top quark one, within the framework of the Two Higgs Doublet Model Type-II
(2HDM-II). Upon examining two scenarios, one featuring a singlet $(T)$
(2HDM-II+$(T)$) and another a doublet $(TB)$ (2HDM-II+$(TB)$), we discover that
the presence of VLQs has a significant effect on the (pseudo)scalar sector of
the 2HDM-II. In particular, this leads to a reduction in the strict constraint
on the mass of the charged Higgs boson, which is imposed by $B$-physics
observables, specifically $B\to X_s\gamma$. {The observed reduction stems from
modifications in the charged Higgs couplings to the Standard Model (SM) top and
bottom quarks}. Notably, the degree of this reduction varies distinctly between
the singlet 2HDM+$(T)$ and doublet 2HDM+$(TB)$ scenarios. Additionally, our
investigation extends to constraints imposed by the oblique parameters $S$ and
$T$ on the VLQ mixing angles. Furthermore, to facilitate efficient exploration
of the '2HDM-II+VLQ' parameter space, we present results on pair production of
VLQs $T$ ($pp\to T\bar T$), followed by $T\to H^\pm b$ and $H^\pm \to tb$
decays, yielding a distinctive $2t4b$ final state. This investigation thus
provides valuable insights guiding the search for extended Higgs and quark
sectors at the Large Hadron Collider (LHC) at CERN. | hep-ph |
Chiral Restoration in the Early Universe: Pion Halo in the Sky: < \psibarpsi > vanishing above $T_c$ indicates chiral symmetry restoration at
high $T$. But is it the old $T=0$ chiral symmetry that is `restored'? In this
talk, I report on the spacetime quantization of the BPFTW effective action for
quarks in a hot environ. The fermion propagator is known to give a
pseudo-Lorentz invariant particle pole as well as new spacelike cuts. Our
quantization shows that the spacelike cuts directly lead to a thermal vacuum
that is a generalized NJL state, with a curious $90^{o}$ phase. This $90^{o}$
is responsible for < \psibarpsi > vanishing at high $T$. The thermal vacuum is
invariant under a new chiral charge, but continues to break the old zero
temperature chirality. Our quantization suggests a new class of order
parameters that probe the physics of these spacelike cuts. In usual scenario,
the pion dissociates in the early alphabet soup. With this new understanding of
the thermal vacuum, the pion remains a Nambu-Goldstone particle at high $T$,
and will not dissociate. It propagates at the speed of light but with a halo. | hep-ph |
Studying the production mechanisms of light meson resonances in two-pion
photoproduction: a Regge approach: A calculation of the angular moments of two-pion photoproduction is
presented. The underlying theoretical model encodes the prominent $\rho(770)$
resonance and the expected leading background contribution coming from the Deck
mechanism. The model contains a number of free parameters which are fit to
experimental data. A good description of the angular moments is obtained. | hep-ph |
Probing general $U(1)'$ models with non-universal lepton charges at
FASER/FASER2, COHERENT and long-baseline oscillation experiments: The general anomaly-free $U(1)'$ models allow non-universal lepton charges.
We explore the sensitivities of FASER/FASER2, COHERENT and DUNE/T2HK precision
experiments to the new gauge boson $Z'$ and the new CP-even scalar $\phi$. With
non-universal lepton charges, distinctive reaches at FASER/FASER2 emerge in the
regime of low $m_{Z'}$ and small gauge coupling $g_{BL}$ for different $U(1)'$
charge setups. The COHERENT experiment and the future long-baseline experiments
DUNE/T2HK also provide complementary probes to the available parameter space.
For $m_\phi < 2m_{Z'}$, the search for the scalar $\phi$ at FASER/FASER2 is
sensitive to the mixing angle between the scalar singlet and the SM Higgs. In
the case of $m_\phi > 2m_{Z'}$, the kinematically allowed decay $\phi\to Z' Z'$
changes the lifetime and decay rates of the scalar $\phi$. The sensitivity
reach highly depends on the $Z'$ mass and the gauge coupling $g_{BL}$. | hep-ph |
Theoretical Expectations for the Muon's Electric Dipole Moment: We examine the muon's electric dipole moment $\dmu$ from a variety of
theoretical perspectives. We point out that the reported deviation in the
muon's g-2 can be due partially or even entirely to a new physics contribution
to the muon's {\em electric} dipole moment. In fact, the recent g-2 measurement
provides the most stringent bound on $\dmu$ to date. This ambiguity could be
definitively resolved by the dedicated search for $\dmu$ recently proposed. We
then consider both model-independent and supersymmetric frameworks. Under the
assumptions of scalar degeneracy, proportionality, and flavor conservation, the
theoretical expectations for $\dmu$ in supersymmetry fall just below the
proposed sensitivity. However, non-degeneracy can give an order of magnitude
enhancement, and lepton flavor violation can lead to $\dmu$ of order $10^{-22}$
e cm, two orders of magnitude above the sensitivity of the $\dmu$ experiment.
We present compact expressions for leptonic dipole moments and lepton flavor
violating amplitudes. We also derive new limits on the amount of flavor
violation allowed and demonstrate that approximations previously used to obtain
such limits are highly inaccurate in much of parameter space. | hep-ph |
Theory of Small $x$ Deep Inelastic Scattering NLO Evaluations, and low
$Q^2$ Analysis: We calculate structure functions at small $x$ both under the assumption of a
hard singularity (a power behaviour $x^{-\lambda}, \lambda$ positive, for
$x\rightarrow 0$) or that of a soft-Pomeron dominated behaviour, also called
double scaling limit, for the singlet component. A full next to leading order
(NLO) analysis is carried for the functions $F_2, F_{\rm Glue}$ and the
longitudinal one $F_L$ in $ep$ scattering, and for $x F_3$ in neutrino
scattering. The results of the calculations are compared with data (HERA) in
the range $x\leq 0.032, 10 gev^2\leq Q^2\leq 1 500 gev^2$. We get reasonable
fits, with a chi-squared/d.o.f.$\sim 2$, for both assumptions, but none of them
gives a fully satisfactory description. The results improve substantially if
combining a soft and a hard component; in this case it is even possible to
extend the analysis, phenomenologically, to small values of $Q^2$, $0.31
gev^2\leq Q^2\leq 8.5 gev^2$, and in the $x$ range $6\times10^{-6}\lsim x \lsim
0.04$, with the same hard plus soft Pomeron hypothesis by assuming a saturating
expression for the strong coupling,
$\tilde{\alpha}_s(Q^2)=4\pi/\beta_0\log[(Q^2+\Lambda_{eff}^2)/\Lambda_{eff}^2]$
The description for low $Q^2$ implies self-consistent values for the parameters
in the exponents of $x$. One gets, for the Regge intercepts,
$\alpha_{\rho}(0)=0.48$ and $\alpha_P(0)=1.470$ [$\lambda=0.470$], in uncanny
agreement with other determinations of these parameters, in particular the
results of the large $Q^2$ fits. The fit to is so good that we may look (at
large $Q^2$) for signals of a "triple Pomeron" vertex; some evidence is found. | hep-ph |
Supersymmetric SU(3) X U(1) Gauge Model: Higgs Structure at the
Electroweak Scale: We consider a supersymmetric version of the recently proposed SU(3) X U(1)
extended gauge model. We show that it is possible to have only two Higgs
doublets at the SU(2) X U(1) energy scale but they are not those of the minimal
supersymmetric standard model. In particular, the upper bound on the lightest
scalar boson of this model is $4 M_Z \sin \theta_W$ at tree level and goes up
to 189 GeV after radiative corrections. | hep-ph |
Tests of Lorentz symmetry: A number of approaches to fundamental physics can lead to the violation of
Lorentz and CPT symmetry. This talk discusses the low-energy phenomenology
associated with such effects and reviews various sample experiments within this
context. | hep-ph |
Properties of excited charmed-bottom mesons: We calculate the spectrum of $B_c$ mesons using a non-relativistic quark
potential model. Using the calculated wave functions, we compute the radiative
widths of $B_c$ excited states. The strong decay widths are calculated in a
modified $^3P_0$ model, assuming harmonic oscillator wave functions. The
hadronic transition rates of $B_c$ mesons are calculated using the Kuang-Yan
approach. These results are used to determine branching ratios of possible
decay channels of several $B_c$ excited states. Calculated branching ratios are
then combined with production cross section of $B_c$ states at the LHC to
suggest strategies to find missing excited states of $B_c$ mesons. | hep-ph |
Radiative corrections to $h^0\to WW^*/ZZ^*\to 4$\,leptons in the MSSM: The electroweak $\mc O(\alpha)$ radiative corrections to the decay of the
lightest MSSM Higgs boson to four leptons are presented, improved by the
two-loop corrections provided by the program package FeynHiggs. We also analyze
the results in the decoupling limit and investigate the numeric impact of
contributions from the genuine supersymmetric particle spectrum. | hep-ph |
Thermodynamic instabilities in dynamical quark models with complex
conjugate mass poles: We show that the CJT thermodynamic potential of dynamical quark models with a
quark propagator represented by complex conjugate mass poles inevitably
exhibits thermodynamic instabilities. We find that the minimal coupling of the
quark sector to a Polyakov loop potential can strongly suppress but not
completely remove such instabilities. This general effect is explicitly
demonstrated in the framework of a covariant, chirally symmetric, effective
quark model. | hep-ph |
The LHCb pentaquark as a $\bar{D}^*Σ_c-\bar{D}^*Σ_c^*$
molecular state: We perform a theoretical analysis of the $\Lambda_b \to J/\psi K^- p$
reaction from where a recent LHCb experiment extracts a $\Lambda(1405)$
contribution in the $K^- p$ spectrum close to threshold and two baryon states
of hidden charm in the $J/\psi\,p$ spectrum. We recall that baryon states of
this type have been theoretically predicted matching the mass, width and $J^P$
of the experiment, concretely some states built up from the $J/\psi\, N$, $\bar
D^* \Lambda_c$, $\bar D^* \Sigma_c$, $\bar D \Sigma^*_c$ and $\bar D^*
\Sigma^*_c$ coupled channels. We assume that the observed narrow state around
4450 MeV has this nature and we are able to describe simultaneously the shapes
and relative strength of the the $K^- p$ mass distribution close to threshold
and the peak of the $J/\psi\,p$ distribution, with values of the $J/\psi\, p$
coupling to the resonance in line with the theoretical ones. The non trivial
matching of many properties gives support to a $J^P=3/2^-$ assignment to this
state and to its nature as a molecular state mostly made of $\bar D^* \Sigma_c$
and $\bar D^* \Sigma^*_c$. | hep-ph |
Next-to-Leading-Order Corrections to the Production of Heavy-Flavour
Jets in e+e- Collisions: In this thesis we describe the calculation of the process e+ e- --> Z/gamma
-> Q Qbar + X, where Q is a heavy quark, X is anything else at order alpha_s^2. | hep-ph |
Sun Heated MeV-scale Dark Matter and the XENON1T Electron Recoil Excess: The XENON1T collaboration reported an excess of the low-energy electron
recoil events between 1 and 7 keV. We explore the possibility to explain such
an anomaly by the MeV-scale dark matter (DM) heated by the interior of the Sun
due to the same DM-electron interaction as in the detector. The kinetic
energies of heated DM particles can reach a few keV, and can potentially
account for the excess signals detected by XENON1T. We study different form
factors of the DM-electron interactions, $F(q)\propto q^i$ with $i=0,1,2$ and
$q$ being the momentum exchange, and find that for all these cases the
inclusion of the Sun-heated DM component improves the fit to the XENON1T data.
The inferred DM-electron scattering cross section (at $q=\alpha m_e$ where
$\alpha$ is the fine structure constant and $m_e$ is electron mass) is from
$\sim 10^{-38}$~cm$^2$ (for $i=0$) to $\sim 10^{-42}$~cm$^2$ (for $i=2$). We
also derive constraints on the DM-electron cross sections for different form
factors, which are stronger than previous results with similar assumptions. We
emphasize that the Sun-heated DM scenario relies on the minimum assumption on
DM models, which serves as a general explanation of the XENON1T anomaly via
DM-electron interaction. The spectrum of the Sun-heated DM is typically soft
comparing to other boosted DM, so the small recoil events are expected to be
abundant in this scenario. More sensitive direct detection experiments with
lower thresholds can possibly distinguish this scenario with other boosted DM
models or solar axion models. | hep-ph |
Fast neutrino flavor conversions near the supernova core with realistic
flavor-dependent angular distributions: It has been recently pointed out that neutrino fluxes from a supernova can
show substantial flavor conversions almost immediately above the core. Using
linear stability analyses and numerical solutions of the fully nonlinear
equations of motion, we perform a detailed study of these fast conversions,
focussing on the region just above the supernova core. We carefully specify the
instabilities for evolution in space or time, andfind that neutrinos travelling
towards the core make fast conversions more generic, i.e., possible for a wider
range of flux ratios and angular asymmetries that produce a crossing between
the zenith-angle spectra of $\nu_e$ and ${\bar\nu_e}$. Using fluxes and angular
distributions predicted by supernova simulations, we find that fast conversions
can occur within tens of nanoseconds, only a few meters away from the putative
neutrinospheres. If these fast flavor conversions indeed take place, they would
have important implications for the supernova explosion mechanism and
nucleosynthesis. | hep-ph |
Supernova Bounds on Neutrino Properties: a mini-review: This talk summarizes our recent work which studied the impact of resonant
neutrino conversion induced by some non-standard neutrino properties beyond
mass and mixing, such as neutrino magnetic moment, lepton-flavor
non-universality as well as flavor changing neutral current interactions in
SUSY models with broken R parity, on supernova physics. | hep-ph |
g_μ- 2 in Supersymmetry: The 2.6 sigma deviation in the muon's anomalous magnetic moment has strong
implications for supersymmetry. In the most model-independent analysis to date,
we consider gaugino masses with arbitrary magnitude and phase, and sleptons
with arbitrary masses and left-right mixings. For tan(beta)=50, we find that 1
sigma agreement requires at least one charged superpartner with mass below 570
GeV; at 2 sigma, this upper bound shifts to 850 GeV. The deviation is
remarkably consistent with all constraints from colliders, dark matter, and b
-> s gamma in supergravity models, but disfavors the characteristic gaugino
mass relations of anomaly-mediation. | hep-ph |
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