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Feynman rules for the rational part of the Electroweak 1-loop amplitudes: We present the complete set of Feynman rules producing the rational terms of
kind R_2 needed to perform any 1-loop calculation in the Electroweak Standard
Model. Our results are given both in the 't Hooft-Veltman and in the Four
Dimensional Helicity regularization schemes. We also verified, by using both
the 't Hooft-Feynman gauge and the Background Field Method, a huge set of Ward
identities -up to 4-points- for the complete rational part of the Electroweak
amplitudes. This provides a stringent check of our results and, as a
by-product, an explicit test of the gauge invariance of the Four Dimensional
Helicity regularization scheme in the complete Standard Model at 1-loop. The
formulae presented in this paper provide the last missing piece for completely
automatizing, in the framework of the OPP method, the 1-loop calculations in
the SU(3) X SU(2) X U(1) Standard Model. | hep-ph |
The $θ$-Vacua and the Leutwyler--Smilga Scaling Regime: The partition function of QCD is studied in the Leutwyler--Smilga scaling
regime for an arbitrary number of quark flavors and masses including the
contributions from all winding numbers. For $N_f=2$ and degenerate quark
masses, the partition function becomes independent of the quark masses at
$\theta=\pi$ and subsequently the scalar chiral condensate vanishes. There is a
discontinuity at $\theta=\pi$ in the first derivative of the energy density
with respect to $\theta$ corresponding to the first--order phase transition in
which CP is spontaneously broken, known as Dashen's phenomena. These properties
are found to be insensitive to both the pattern of chiral symmetry breaking and
the representation of the quark fields. | hep-ph |
Composite Dynamics in the Early Universe: We study the occurrence of a strong first-order electroweak phase transition
in composite Higgs models. Minimal constructions realising this scenario are
based on the coset SO(6)/SO(5) which delivers an extended Higgs sector with an
additional scalar. In such models, a two-step phase transition can be obtained
with the scalar singlet acquiring a vacuum expectation value at intermediate
temperatures. A bonus of the Nambu-Goldstone boson nature of the scalar-sector
dynamics is the presence of non-renormalisable Higgs interactions that can
trigger additional sources of CP violation needed to realise baryogenesis at
the electroweak scale. Another interesting aspect of this scenario is the
generation of gravitational wave signatures that can be observed at future
space-based interferometers. | hep-ph |
Study of LHC Searches for a Lepton and Many Jets: Searches for new physics in high-multiplicity events with little or no
missing energy are an important component of the LHC program, complementary to
analyses that rely on missing energy. We consider the potential reach of
searches for events with a lepton and six or more jets, and show they can
provide increased sensitivity to many supersymmetric and exotic models that
would not be detected through standard missing-energy analyses. Among these are
supersymmetric models with gauge mediation, R-parity violation, and light
hidden sectors. Moreover, ATLAS and CMS measurements suggest the primary
background in this channel is from t-tbar, rather than W+jets or QCD, which
reduces the complexity of background modeling necessary for such a search. We
also comment on related searches where the lepton is replaced with another
visible object, such as a Z boson. | hep-ph |
Distinguishing the Color Octet Axial-Vector-like Particle for Top Quark
Asymmetry via Color Flow Method at the LHC: The excess in top quark forward-backward asymmetry has been a hot topic in
recent years. Although there are many proposals to explain it, most of them can
not fit the differential distributions well. The color octet axial-vector like
particle, with mass near the top quark pair threshold, is still a good
description of the differential distributions. We study how to distinguish the
color singlet and octet mediating particles in top quark pair production by
adopting the color flow method. For the first time, we show that such a
proposal for the froward-backward asymmetry can be cross-checked indirectly at
the LHC. | hep-ph |
Unusual condensates in quark and atomic systems: In these lectures we discuss condensates which are formed in quark matter
when it is squeezed and in a gas of fermionic atoms when it is cooled. The
behavior of these two seemingly very different systems reveals striking
similarities. In particular, in both systems the Bose-Einstein condensate to
Bardeen--Cooper-Schrieffer (BEC-BCS) crossover takes place. | hep-ph |
New extraction of CP violation in b-baryon decays: We study CP violation in b-baryon decays of $\Xi_b^- \to \Xi^- D$ with $D =
D^0, \bar{D}^0$ and $D_i~(i=1,2)$. We find that these baryonic decay processes
provide an ideal opportunity to measure the weak phase due to the absence of
the relative strong phase. Explicitly, we relate $\bar{\rho}$ and $\bar{\eta}$
the CKM elements with the decay rate ratios of $R_i= \Gamma(\Xi_b^- \to
\Xi^-D_{i} ) / \Gamma( \Xi_b^- \to \Xi^-D^0 )$ without the charge conjugate
states. As a complementary, we also examine the decay distributions of
$\Lambda_b \to \Lambda(\to p \pi^- ) D$. There are in total 32 decay
observables, which can be parameterized by 9 real parameters, allowing the
experiments to extract the angle $\gamma\equiv
\arg(-V_{ud}V_{ub}^*/V_{cd}V_{cb}^*)$ in the CKM unitarity triangle. In
addition, the feasibilities of the experimental measurements are discussed. We
find that $\bar{\rho}$ and $\bar{\eta}$ can be extracted at LHCb Run3 from
$\Xi_b^- \to \Xi^- D$, and a full analysis of $\Lambda_b \to \Lambda(\to p
\pi^-)D$ is available at LHCb Run4. | hep-ph |
Unification of SUSY breaking and GUT breaking: We build explicit supersymmetric unification models where grand unified gauge
symmetry breaking and supersymmetry (SUSY) breaking are caused by the same
sector. Besides, the SM-charged particles are also predicted by the symmetry
breaking sector, and they give the soft SUSY breaking terms through the
so-called gauge mediation. We investigate the mass spectrums in an explicit
model with SU(5) and additional gauge groups, and discuss its phenomenological
aspects. Especially, nonzero A-term and B-term are generated at one-loop level
according to the mediation via the vector superfields, so that the electro-weak
symmetry breaking and 125 GeV Higgs mass may be achieved by the large B-term
and A-term even if the stop mass is around 1 TeV. | hep-ph |
An Updated Analysis of Inert Higgs Doublet Model in light of the Recent
Results from LUX, PLANCK, AMS-02 and LHC: In light of the recent discovery by the ATLAS and CMS experiments at the
Large Hadron Collider (LHC) of a Higgs-like particle with a narrow mass range
of 125-126 GeV, we perform an updated analysis on one of the popular scalar
dark matter models, the Inert Higgs Doublet Model (IHDM). We take into account
in our likelihood analysis of various experimental constraints, including
recent relic density measurement, dark matter direct and indirect detection
constraints as well as the latest collider constraints on the invisible decay
width of the Higgs boson and monojet search at the LHC. It is shown that if the
invisible decay of the standard model Higgs boson is open, LHC as well as
direct detection experiments like LUX and XENON100 could put stringent limits
on the Higgs boson couplings to dark matter. We find that the most favoured
parameter space for IHDM corresponds to dark matter with a mass less than 100
GeV or so. In particular, the best-fit points are at the dark matter mass
around 70 GeV where the invisible Higgs decay to dark matter is closed. Scalar
dark matter in the higher mass range of 0.5-4 TeV is also explored in our
study. Projected sensitivities for the future experiments of monojet at LHC-14,
XENON1T and AMS-02 one year antiproton flux are shown to put further
constraints on the existing parameter space of IHDM. | hep-ph |
Electroweak Physics: Theoretical Overview: I give an overview of the theory status of predictions for single W and Z
boson production at hadron colliders. I briefly report on work in progress for
improvements necessary to match the anticipated high precision of electroweak
measurements, such as the W mass and width, at the Fermilab Tevatron p anti-p
and the CERN LHC pp colliders. | hep-ph |
Generalized Friedberg-Lee model for CP violation in neutrino physics: We propose a phenomenological model of Dirac neutrino mass operator based on
the Fridberg-Lee (FL) neutrino mass model to include CP violation. By
considering the most general set of complex coefficients, and imposing the
condition that the mass eigenvalues are real, we find a neutrino mass matrix
which is non-hermitian, symmetric and magic. In particular, we find that the
requirement of obtaining real mass eigenvalues by transferring the residual
phases to the mass eigenstates self-consistently, dictates the following
relationship between the imaginary part of the mass matrix elements $B$ and the
parameters of the FL model:
$B=\pm\sqrt{3/4(a-b_{r})^{2}\sin^{2}2\theta_{13}\cos^{2}\theta_{12}}$. We
obtain inverted neutrino mass hierarchy, $m_{3}=0$. Making a correspondence
between our model and the experimental data produces stringent conditions on
the parameters as follows:
$35.06^{\circ}\lesssim\theta_{12}\lesssim36.27^{\circ}$, $\theta_{23}=
45^{\circ}$, $7.27^{\circ}\lesssim\theta_{13}\lesssim11.09^{\circ}$, and
$82.03^{\circ}\lesssim\delta\lesssim85.37^{\circ}$. We get mildly broken
$\mu-\tau$ symmetry, which reduces the resultant neutrino mixing pattern from
tribimaximal (TBM) to trimaximal (TM). The CP violation as measured by the
Jarlskog parameter is restricted by $0.027\lesssim J\lesssim0.044$. | hep-ph |
Direct detection rate of heavy Higgsino-like and Wino-like dark matter: A large class of viable dark matter models contain a WIMP candidate that is a
component of a new electroweak multiplet whose mass $M$ is large compared to
the electroweak scale $m_W$. A generic amplitude-level cancellation in such
models yields a severe suppression of the cross section for WIMP-nucleon
scattering, making it important to assess the impact of formally subleading
effects. The power correction of order $m_W/M$ to the heavy WIMP limit is
computed for electroweak doublet (Higgsino-like) dark matter candidates, and a
modern model of nuclear modifications to the free nucleon cross section is
evaluated. Corrections to the pure Higgsino limit are determined by a single
parameter through first order in the heavy WIMP expansion. Current and
projected experimental bounds on this parameter are investigated. The direct
detection signal in the pure Higgsino limit remains below neutrino backgrounds
for WIMPs in the TeV mass range. Nuclear corrections are applied also to the
heavy Wino case, completing the investigation of combined subleading effects
from perturbative QCD, $1/M$ power corrections, and nuclear modifications. | hep-ph |
PHOTOS Interface in C++; Technical and Physics Documentation: For five years now, PHOTOS Monte Carlo for bremsstrahlung in the decay of
particles and resonances has been available with an interface to the C++ HepMC
event record. The main purpose of the present paper is to document the
technical aspects of the PHOTOS Monte Carlo installation and present version
use. A multitude of test results and examples are distributed together with the
program code.
The PHOTOS C++ physics precision is better than its FORTRAN predecessor and
more convenient steering options are also available. An algorithm for the event
record interface necessary for process dependent photon emission kernel is
implemented. It is used in Z and W decays for kernels of complete first order
matrix elements of the decays. Additional emission of final state lepton pairs
is also available.
Physics assumptions used in the program and properties of the solution are
reviewed. In particular, it is explained how the second order matrix elements
were used in design and validation of the program iteration procedure. Also, it
is explained that the phase space parametrization used in the program is exact. | hep-ph |
Characteristics of Cherenkov Radiation in Naturally Occuring Ice: We revisit the theory of Cherenkov radiation in uniaxial crystals.
Historically, a number of flawed attempts have been made at explaining this
radiation phenomenon and a consistent error-free description is nowhere
available. We apply our calculation to a large modern day telescope - IceCube.
Being located at the Antarctica, this detector makes use of the naturally
occuring ice as a medium to generate Cherenkov radiation. However, due to the
high pressure at the depth of the detector site, large volumes of hexagonal ice
crystals are formed. We calculate how this affects the Cherenkov radiation
yield and angular dependence. We conclude that the effect is small, at most
about a percent, and would only be relevant in future high precision
instruments like e.g. Precision IceCube Next Generation Upgrade (PINGU). For
radio-Cherenkov experiments which use the presence of a clear Cherenkov cone to
determine the arrival direction, any variation in emission angle will directly
and linearly translate into a change in apparent neutrino direction. In
closing, we also describe a simple experiment to test this formalism, and
calculate the impact of anisotropy on light-yields from lead tungstate crystals
as used, for example, in the CMS calorimeter at the CERN LHC. | hep-ph |
Spinless Salpeter Equation: Some (Semi-) Analytical Approaches: Several techniques for deriving semianalytical bounds on the energy
eigenvalues of the spinless Salpeter equation and for estimating the quality of
the corresponding approximate eigenstates are reviewed. | hep-ph |
The Cosmological Moduli Problem and Preheating: Many models of supersymmetry breaking, in the context of either supergravity
or superstring theories, predict the presence of particles with
Planck-suppressed couplings and masses around the weak scale. These particles
are generically called moduli. The excessive production of moduli in the early
Universe jeopardizes the successful predictions of nucleosynthesis. In this
paper we show that the efficient generation of these dangerous relics is an
unescapable consequence of a wide variety of inflationary models which have a
preheating stage. Moduli are generated as coherent states in a novel way which
differs from the usual production mechanism during parametric resonance. The
corresponding limits on the reheating temperature are often very tight and more
severe than the bound of 10^9 GeV coming from the production of moduli via
thermal scatterings during reheating. | hep-ph |
$0^{+}$ fully-charmed tetraquark states: Motivated by the LHCb's new observation of structures in the $J/\psi$-pair
invariant mass spectrum, for which could be classified as possible
$cc\bar{c}\bar{c}$ tetraquark candidates, we systematically study $0^{+}$
fully-charmed tetraquark states through QCD sum rules. Making the development
of calculation techniques to fourfold heavy hadronic systems, four different
configuration currents with $0^{+}$ are considered and vacuum condensates up to
dimension $6$ are included in the operator product expansion (OPE). Finally,
mass values acquired for $0^{+}$ $cc\bar{c}\bar{c}$ tetraquark states agree
well with the experimental data of the broad structure, which supports that it
could be a $0^{+}$ fully-charmed tetraquark state. | hep-ph |
Pomeron structure functions from HERA to Tevatron and LHC: The proton diffractive structure function $F_2^{D(3)}$ measured in the H1 and
ZEUS experiments at HERA are analysed in terms of perturbative QCD in the
perspective of the QCD extrapolation to the Tevatron and the LHC. It is shown
that both data sets can be well described by a QCD analysis in which point-like
parton distributions, evolving according to the next-leading DGLAP equations,
are assigned to the leading and sub-leading Regge exchanges. For present data
from H1 and ZEUS the gluon distributions are found to be quite different and we
give the corresponding sets of quark and gluon parton distributions for the
Pomeron, extracted from the two experiments. An extrapolation to the Tevatron
range is compared with CDF data on single diffraction. Conclusions on
factorization breaking between HERA and Tevatron critically depend on whether
H1 (strong violation) or ZEUS (compatibility at low $\beta$) fits are taken
into account. Using the double Pomeron formulation in central diffractive dijet
production we show that the Tevatron mass fraction is much sensitive to the
high $\beta$ tail of the gluon in the Pomeron, suggesting a new way of handling
the otherwise badly known gluon distribution in the Pomeron. Extrapolation of
the fits to very high $Q^2$ are given since they will be relevant for QCD and
diffraction studies at the LHC. | hep-ph |
Non standard neutrino interactions at LEP2 and the LHC: We consider Non-Standard neutrino Interactions (NSI) connecting two neutrinos
with two first-generation fermions ($e, u$ or $d$), which we assume to arise at
at dimension eight due to New Physics. The coefficient is normalised as $4
\epsilon G_F/\sqrt{2}$. We explore signatures of NSI-on-electrons at LEP2, and
of NSI-on-quarks at the LHC, treating the NSI as contact interactions at both
energies. In models where the coefficients of dangerous dimension six operators
are suppressed by cancellations, LEP2 provides interesting bounds on NSI
operators ($\epsilon \lsim 10^{-2} - 10^{-3}$), which arise because $\sqrt{s}
\sim 200$ GeV, and the cancellation applied at zero momentum transfer. At the
LHC, we use the Equivalence Theorem, which relates the longitudinal $W$ to the
Higgs, to estimate the rate for $\bar{q} q W^+W^- e_\alpha^+ e_\beta^-$ induced
by NSI. We find that the cross-section is small, but that the outgoing
particles have very high $p_T > 400$ GeV, which reduces the issue of
backgrounds. In a conservative scenario, we find that the LHC at 14 TeV and
with 100 fb$^{-1}$ of data would have a sensitivity to $\epsilon \gsim 3 \times
10^{-3}$. | hep-ph |
$W$ mass in a model with vector-like leptons and $U(1)^\prime$: We study the effects of vector-like leptons on the $W$ boson mass in a model
with a vector-like $U(1)^\prime$ gauge symmetry. This model provides
simultaneous explanations for the recent anomalies in the muon anomalous
magnetic moment and the semi-leptonic decays of $B$ mesons. We found that the
recent result of the $W$ boson mass precise measurement at CDF can be explained
if the charged (neutral) vector-like lepton is lighter than 250 (80) GeV. The
light vector-like leptons may not be excluded by collider experiments if these
decay to a physical mode of the $U(1)^\prime$ breaking scalar field. | hep-ph |
Density Fluctuations as Signature of a Non--Equilibrium First Order
Phase Transition: We show that in the presence of spinodal instabilities which develop at a
first order phase transition, the fluctuations of conserved charges can be as
strong as those at the critical end point (CEP). In particular, the net baryon
number susceptibility diverges as the system crosses the isothermal spinodal
lines. This indicates that charge density fluctuations can be used not only to
probe the CEP but also the non--equilibrium first order chiral phase transition
in heavy ion collisions. | hep-ph |
Precision Electroweak Data: Phenomenological Analysis: The precision electroweak program, including weak neutral current (WNC),
$Z$-pole, and high energy collider experiments, has been the primary prediction
and test of electroweak unification. It has established that the standard model
(SM) is correct and unique to first approximation, establishing the gauge
principle as well as the SM gauge group and representations; shown that the SM
is correct at loop level, confirming the basic principles of renormalizable
gauge theory and allowing the successful prediction or constraint on $m_t$,
$\alpha_s$, and $M_H$; severely constrained new physics at the TeV scale, with
the ideas of unification strongly favored over TeV-scale compositeness; and
yielded precise values for the gauge couplings, consistent with
(supersymmetric) gauge unification. | hep-ph |
Analysis of the higher twist GTMD $F_{31}$ for proton in the light-front
quark-diquark model: In the light-front quark-diquark model (LFQDM), the higher twist generalized
transverse momentum dependent distribution (GTMD) $F_{31}(x, {\bf p_\perp},{\bf
\Delta_\perp})$ for the proton has been analyzed. We have derived the GTMD
overlap equation by the analysis of GTMD correlator, employing the light-front
wave functions in both the scalar and vector diquark situations. With the
relevant 2-D and 3-D figures, the behavior of GTMD $F_{31}(x, {\bf
p_\perp},{\bf \Delta_\perp})$ with variations in its variables has been
illustrated. Further, on applying the transverse momentum dependent
distribution (TMD) limit on GTMD $F_{31}(x, {\bf p_\perp},{\bf \Delta_\perp})$,
the expression of TMD $f_3(x, {\bf p_\perp})$ has been obtained. | hep-ph |
Higgs boson pair production via gluon fusion at N$^3$LO in QCD: We present next-to-next-to-next-to-leading order (N$^3$LO) QCD predictions
for the Higgs boson pair production via gluon fusion at hadron colliders in the
infinite top-quark mass limit. Besides the inclusive total cross sections at
various collision energies, we also provide the invariant mass distribution of
the Higgs boson pair. Our results show that the N$^3$LO QCD corrections enhance
the next-to-next-to-leading order cross section by $3.0\%$ ($2.7\%$) at
$\sqrt{s}=13~(100)$ TeV, while the scale uncertainty is reduced substantially
below $3\%$ ($2\%$). We also find that a judicious scale choice can
significantly improve the perturbative convergence. For the invariant mass
distribution, our calculation demonstrates that the N$^3$LO corrections improve
the scale dependence but almost do not change the shape. | hep-ph |
Strong decays of the charmed mesons $D_1^*(2680)$, $D^*_3(2760)$,
$D_2^*(3000)$: In this article, we assign the higher charmed mesons $D^*_1(2680)$,
$D_3^*(2760)$ and $D_2^*(3000)$ to be the 2S $1^-$, 1D $3^-$ and 1F $2^+$
states, respectively, and study the two-body strong decays to the ground state
charmed mesons and light pseudoscalar mesons with the heavy meson effective
theory. We obtain the ratios among the strong decays, which can be confronted
to the experimental data in the future and shed light on the nature of those
higher charmed mesons. | hep-ph |
Exclusive Radiative Higgs Decays as Probes of Light-Quark Yukawa
Couplings: We present a detailed analysis of the rare exclusive Higgs-boson decays into
a single vector meson and a photon and investigate the possibility of using
these processes to probe the light-quark Yukawa couplings. We work with an
effective Lagrangian with modified Higgs couplings to account for possible
new-physics effects in a model-independent way. The h->V\gamma{} decay rate is
governed by the destructive interference of two amplitudes, one of which
involves the Higgs coupling to the quark anti-quark pair inside the vector
meson. We derive this amplitude at next-to-leading order in \alpha_s using QCD
factorization, including the resummation of large logarithmic corrections and
accounting for the effects of flavor mixing. The high factorization scale
\mu~m_h ensures that our results are rather insensitive to the hadronic
parameters characterizing the light-cone distribution amplitude of the vector
meson. The second amplitude arises from the loop-induced effective
h\gamma\gamma* and h\gamma Z* couplings, where the off-shell gauge boson
converts into the vector meson. We devise a strategy to eliminate theoretical
uncertainties related to this amplitude to almost arbitrary precision. This
opens up the possibility to probe for O(1) modifications of the c- and b-quark
Yukawa couplings and O(30) modifications of the s-quark Yukawa coupling in the
high-luminosity LHC run. In particular, we show that measurements of the ratios
Br(h->\Upsilon(nS)\gamma)/Br(h->\gamma\gamma) and Br(h->bb)/Br(h->\gamma\gamma)
can provide complementary information on the real and imaginary parts of the
b-quark Yukawa coupling. More accurate measurements would be possible at a
future 100 TeV proton-proton collider. | hep-ph |
Ultra-high energy neutrino scattering: Estimates are made of the ultra-high energy neutrino cross sections based on
an extrapolation to very small Bjorken x of the logarithmic Froissart
dependence in x shown previously to provide an excellent fit to the measured
proton structure function F_2^p(x,Q^2) over a broad range of the virtuality
Q^2. Expressions are obtained for both the neutral current and the charged
current cross sections. Comparison with an extrapolation based on perturbative
QCD shows good agreement for energies where both fit data, but our rates are as
much as a factor of 10 smaller for neutrino energies above 10^9 GeV, with
important implications for experiments searching for extra-galactic neutrinos. | hep-ph |
Constraints on cosmic-ray boosted DM in CDEX-10: Dark matter (DM) direct detection experiments have been setting strong limits
on the DM-nucleon scattering cross section at the DM mass above a few GeV, but
leave large parameter space unexplored in the low mass region. DM is likely to
be scattered and boosted by relativistic cosmic rays in the expanding universe
if it can generate nuclear recoils in direct detection experiments to offer
observable signals. Since low energy threshold detectors using Germanium have
provided good constraints on ordinary halo GeV-scale DM, it is necessary to
re-analyze 102.8 kg$\times$day data in the CDEX-10 experiment assuming that DM
is boosted by cosmic rays. For the DM mass range 1 keV $<m_\chi <$ 1 MeV and
the effective distance within 1 kpc, we reach an almost flat floor limit at
$8.32\times10^{-30}$ cm$^2$ on spin-independent DM-nucleon scattering cross
section at a 90\% confidence level. The CDEX-10 result is able to close the gap
unambiguously in the parameter space between MiniBooNE and XENON1T constraints
which was partially hindered by the Earth attenuation effect. We also
quantitatively calculate expected neutrino floor on searching for CRBDM in
future direct detection experiments using Germanium. | hep-ph |
Asteroids for ultralight dark-photon dark-matter detection: Gravitational-wave (GW) detectors that monitor fluctuations in the separation
between inertial test masses (TMs) are sensitive to new forces acting on those
TMs. Ultralight dark-photon dark matter (DPDM) coupled to $U(1)_B$ or
$U(1)_{B-L}$ charges supplies one such force that oscillates with a frequency
set by the DPDM mass. GW detectors operating in different frequency bands are
thus sensitive to different DPDM mass ranges. A recent GW detection proposal
based on monitoring the separation of certain asteroids in the inner Solar
System would have sensitivity to $\mu$Hz frequencies [arXiv:2112.11431]. In
this paper, we show how that proposal would also enable access to new parameter
space for DPDM coupled to $B$ [respectively, $B-L$] charges in the mass range
$5\ [9] \times 10^{-21} \text{eV} \lesssim m_{\text{DM}} \lesssim 2 \times
10^{-19} \text{eV}$, with peak sensitivities about a factor of 500 [50] beyond
current best limits on $\varepsilon_B$ [$\varepsilon_{B-L}$] at $m_{\text{DM}}
\sim 2 \times 10^{-19} \text{eV}$. Sensitivity could be extended up to
$m_{\text{DM}} \sim 2 \times 10^{-18} \text{eV}$ only if noise issues
associated with asteroid rotational motion could be overcome. | hep-ph |
Superluminal neutrinos in long baseline experiments and SN1987a: Precise tests of Lorentz invariance in neutrinos can be performed using long
baseline experiments such as MINOS and OPERA or neutrinos from astrophysical
sources. The MINOS collaboration reported a measurement of the muonic neutrino
velocities that hints to super-luminal propagation, very recently confirmed at
6 sigma by OPERA. We consider a general parametrisation which goes beyond the
usual linear or quadratic violation considered in quantum-gravitational models.
We also propose a toy model showing why Lorentz violation can be specific to
the neutrino sector and give rise to a generic energy behaviour E^alpha, where
alpha is not necessarily an integer number. Supernova bounds and the preferred
MINOS and OPERA regions show a tension, due to the absence of shape distortion
in the neutrino bunch in the far detector of MINOS. The energy independence of
the effect has also been pointed out by the OPERA results. | hep-ph |
Tensor susceptibilities of the vacuum from constituent quarks: We show that the constituent quark model leads to simple expressions for the
isoscalar and isovector tensor susceptibilities of the vacuum. The found values
are negative and of magnitude compatible with QCD-sum-rule parameterizations of
spectral densities in appropriate L=1-meson channels. | hep-ph |
Next-to-leading order QCD corrections to Higgs boson production in
association with a photon via weak-boson fusion at the LHC: Higgs boson production in association with a hard central photon and two
forward tagging jets is expected to provide valuable information on Higgs boson
couplings in a range where it is difficult to disentangle weak-boson fusion
processes from large QCD backgrounds. We present next-to-leading order QCD
corrections to Higgs production in association with a photon via weak-boson
fusion at a hadron collider in the form of a flexible parton-level Monte Carlo
program. The QCD corrections to integrated cross sections are found to be small
for experimentally relevant selection cuts, while the shape of kinematic
distributions can be distorted by up to 20% in some regions of phase space.
Residual scale uncertainties at next-to-leading order are at the few-percent
level. | hep-ph |
Theory-Data Comparisons for Jet Measurements in Hadron-Induced Processes: We present a comprehensive overview of theory-data comparisons for inclusive
jet production. Theory predictions are derived for recent parton distribution
functions and compared with jet data from different hadron-induced processes at
various center-of-mass energies sqrt(s). The comparisons are presented as a
function of jet transverse momentum pT or, alternatively, of the scaling
variable xT = 2pT/sqrt(s). | hep-ph |
Potential for optimizing Higgs boson CP measurement in H to tau tau
decay at LHC and ML techniques: We investigate potential for measuring CP state of the Higgs boson in the H
to tau tau$ decay with consecutive tau-lepton decays in channels: tau^+- to
rho^+- nu_tau and tau^+- to a1^+- nu_tau combined. Subsequent decays rho^+- to
pi^+- pi^0, a1^+- to rho^0 pi^+- and rho^0 to pi^+ pi^- are taken into account.
We will explore extensions of the method, where acoplanarity angle for the
planes build on the visible decay products, pi^+- pi^0 of tau^+- to pi^pm pi^0
nu_tau, was used. The angle is sensitive to transverse spin correlations, thus
to parity.
We show, that in the case of the cascade decays of tau to a1 nu, information
on the CP state of Higgs can be extracted from the acoplanarity angles as well.
Because in the cascade decay a1^+- to rho^0 pi^pm,rho^0 to pi^+ pi^- up to four
planes can be defined, up to 16 distinct acoplanarity angles are available for
H \to tau tau to a1^+ a1^- nu nu decays. These acoplanarities carry in part
supplementary but also correlated information. It is thus cumbersome to
evaluate an overall sensitivity.
We investigate sensitivity potential of such analysis, by developing and
implementing model in the Machine Learning (ML) techniques. We quantify
possible improvements when multi-dimensional phase-space of outgoing decay
products directions is used, instead of 1-dimensional projections i.e. the
acoplanarity angles.
We do not take into account ambiguities resulting from detector uncertainties
or background contamination, we concentrate on usefulness of ML methods and tau
to 3pi nu decays for Higgs boson parity measurement. | hep-ph |
Some implications of lepton flavor violating processes in a
supersymmetric Type II seesaw model at TeV scale: We have conceived a supersymmetric Type II seesaw model at TeV scale, which
has some additional particles consisting of scalar and fermionic triplet Higgs
states, whose masses being around few hundred GeV. In this particular model, we
have studied constraints on the masses of triplet states arising from the
lepton flavor violating (LFV) processes, such as $\mu\to 3e$ and $\mu\to
e\gamma$. We have analyzed the implications of these constraints on other
observable quantities such as the muon anomalous magnetic moment and the decay
patterns of scalar triplet Higgses. Scalar triplet Higgs states can decay into
leptons and into supersymmetric fields. We have found that the constraints from
LFV can effect these various decay modes. | hep-ph |
CP Violation Effects on $B^0_{s,d}\to \it l^+\it l^-$ in Supersymmetry
at Large $\tanβ$: An analytic analysis of the CP violating effects arising from the soft SUSY
breaking parameters on the decays $B^0_{s,d}\to \it l^+\it l^-$ at large
$\tan\beta$ is given. It is found that the phases have a strong effect on the
branching ratio and in some regions of the parameter space they can lead to a
variation of the branching ratio by as much as 1-2 orders of magnitude. These
results have important implications for the discovery of the $B^0_{s}\to
\mu^+\mu^-$ signal in RUNII of the Tevatron and further on how the parameter
space of SUSY models will be limited once the signal is found. | hep-ph |
QCD$\times$QED evolution of TMDs: We consider for the first time the QED corrections to the evolution of
(un)polarized quark and gluon transverse-momentum-dependent distribution and
fragmentation functions (TMDs in general). By extending their operator
definition to QCD$\times$QED, we provide the mixed new anomalous dimensions up
to ${\cal O}(\alpha_s\alpha)$ and the pure QED ones up to ${\cal O}(\alpha^2)$.
These new corrections are universal for all TMDs up to the flavor of the
considered parton, i.e., the full flavor universality of TMD evolution found in
pure QCD is broken in QCD$\times$QED by the presence of the electric charge. In
addition, we provide the leading-order QED corrections to the matching
coefficients of the unpolarized quark TMD parton distribution function onto its
integrated counterparts at ${\cal O}(\alpha_s^0\alpha)$. | hep-ph |
Probing the gluon tomography in photoproduction of di-pions: A sizable $\cos 4\phi$ azimuthal asymmetry in exclusive di-pion production
near $\rho^0$ resonance peak in ultraperipheral heavy ion collisions recently
has been reported by STAR collaboration. We show that both elliptic gluon
Wigner distribution and final state soft photon radiation can give rise to this
azimuthal asymmetry. The fact that the QED effect alone severely underestimates
the observed asymmetry might signal the existence of the nontrivial correlation
in quantum phase distribution of gluons. | hep-ph |
Almost-Goldstone Bosons from Extra-Dimensional Gauge Theories: A mechanism is presented through which very light scalar degrees of freedom
obeying the nonlinear sigma model equation can emerge in spontaneously broken
gauge theories.
The mechanism operates in extra dimensional theories in which a) there are
massless gauge fields present in the theory prior to compactification, and b)
the extra dimensions are inhomogeneous in such a way that symmetry breaking
Higgs fields aquire vevs only at very localised points on the manifold. These
conditions are naturally fulfilled in orbifold compactifications of string
theory. Possible applications include cosmic texture, axions and family
symmetry. | hep-ph |
On nonadiabatic contributions to the neutrino oscillation probability
and the formalism by Kimura, Takamura and Yokomakura: It is shown that it is possible to obtain the analytical expression for the
effective mixing angle in matter using the formalism which was developed by
Kimura, Takamura and Yokomakura for the neutrino oscillation probability in
matter with constant density. If we assume that the imaginary part of the
integral of the difference of the energy eigenvalues of the two levels at each
level-crossing is given by the ratio $\gamma$ of the difference of the energy
eigenvalues of the two levels to the derivative of the effective mixing angle
at the level-crossing, then the nonadiabatic contribution to the oscillation
probability can be expressed analytically by this formalism. We give one
example in which the energy eigenvalues cannot be expressed as roots of a
quadratic equation and we show that our assumption is correct in the
approximation of the small mixing angle. | hep-ph |
The LHC di-photon excess and Gauge Coupling Unification in Extra
$Z^\prime$ Heterotic-String Derived Models: The di-photon excess observed at the LHC can be explained as a Standard Model
singlet that is produced and decays by heavy vector-like colour triplets and
electroweak doublets in one-loop diagrams. The characteristics of the required
spectrum are well motivated in heterotic-string constructions that allow for a
light $Z^\prime$. Anomaly cancellation of the $U(1)_{Z^\prime}$ symmetry
requires the existence of the Standard Model singlet and vector-like states in
the vicinity of the $U(1)_{Z^\prime}$ breaking scale. In this paper we show
that the agreement with the gauge coupling data at one-loop is identical to the
case of the Minimal Supersymmetric Standard Model, owing to cancellations
between the additional states. We further show that effects arising from heavy
thresholds may push the supersymmetric spectrum beyond the reach of the LHC,
while maintaining the agreement with the gauge coupling data. We show that the
string inspired model can indeed account for the observed signal and discuss
the feasibility of obtaining viable scalar mass spectrum. | hep-ph |
WIMPs during Reheating: Weakly Interacting Massive Particles (WIMPs) are among the best-motivated
dark matter candidates. In the standard scenario where the freeze-out occurs
well after the end of inflationary reheating, they are in tension with the
severe experimental constraints. Here, we investigate the thermal freeze-out of
WIMPs occurring {\it during} reheating, while the inflaton $\phi$ coherently
oscillates in a generic potential $\propto \phi^n$. Depending on the value of
$n$ and the spin of the inflaton decaying products, the evolution of the
radiation and inflaton energy densities can show distinct features, therefore,
having a considerable impact on the freeze-out behavior of WIMPs. As a result
of the injection of entropy during reheating, the parameter space compatible
with the observed DM relic abundance is enlarged. In particular, the WIMP
thermally averaged annihilation cross-section can be several magnitudes lower
than that in the standard case. Finally, we discuss the current bounds from
dark matter indirect detection experiments, and explore future challenges and
opportunities. | hep-ph |
Exclusive Radiative Decays of B Mesons in QCD Factorization: We discuss exclusive radiative decays in QCD factorization within the
Standard Model. In particular, we consider the decays B -> V gamma, with a
vector meson K* or rho in the final state, and the double radiative modes B_s
-> gamma gamma and B_d -> gamma gamma. At quark level, all these decays are
governed by the flavour-changing neutral-current b -> s gamma or b -> d gamma
transitions, which appear at the one-loop level in the Standard Model. Such
processes allow us to study CP violation and the interplay of strong and
electroweak interactions, to determine parameters of the CKM matrix, and to
search for New Physics. The exclusive decays are experimentally better
accessible, but pose more problems for the theoretical analysis. The
heavy-quark limit m_b >> Lambda_QCD, however, allows to systematically separate
perturbatively calculable hard scattering kernels from nonperturbative form
factors and universal light-cone distribution amplitudes. For the B -> V gamma
decays we evaluate the leading Lambda_QCD/m_b contributions complete to
next-to-leading order in QCD, including also QCD penguin operators. The double
radiative B -> gamma gamma decays are analyzed with leading-logarithmic
accuracy. We predict branching ratios, CP and isospin asymmetries, and estimate
U-spin breaking effects for B -> K* gamma and B -> rho gamma. For the B ->
gamma gamma decays we give numerical results for branching ratios and CP
asymmetries. | hep-ph |
Radiative corrections to the Dalitz plot of K_{l3}^0 decays: A model-independent expression for the Dalitz plot of semileptonic decays of
neutral kaons, K_{l3}^0, including radiative corrections to order
(\alpha/\pi)(q/M_1), where q is the momentum transfer and M_1 is the mass of
the kaon, is presented. The model dependence of radiative corrections is kept
in a general form within this approximation, which is suitable for
model-independent experimental analyses. Expressions for bremsstrahlung
radiative corrections are presented in two forms: one with the triple integral
over the kinematical variables of the photon ready to be performed numerically
and the other one in a fully analytical form. The final result is restricted to
the so-called three-body region of the Dalitz plot and it is not compromised to
fixing the values of the form factors at predetermined values. | hep-ph |
Ansatz for small FCNC with a non-universal $Z^\prime$: It is well known that a non-universal $Z^\prime$ induces tree-level FCNC
which are severely constrained by experiment, most notably meson mixing. We
point out that there is a class of models, with a down-quark mass matrix of the
Georgi-Jarlskog form, in which the FCNC in the down-type quark sector vanish or
are strongly suppressed. The largest FCNC in these models would occur in the
$tc$ transition with a strength comparable to $V_{ts}$. | hep-ph |
The Dualized Standard Model and its Applications---an Interim Report: Based on a nonabelian generalization of electric-magnetic duality, the
Dualized Standard Model (DSM) suggests a natural explanation for exactly 3
generations of fermions as the `dual colour' $\widetilde{SU}(3)$ symmetry
broken in a particular manner. The resulting scheme then offers on the one hand
a fermion mass hierarchy and a perturbative method for calculating the mass and
mixing parameters of the Standard Model fermions, and on the other testable
predictions for new phenomena ranging from rare meson decays to ultra-high
energy cosmic rays. Calculations to 1-loop order gives, at the cost of
adjusting only 3 real parameters, values for the following quantities all
(except one) in very good agreement with experiment: the quark CKM matrix
elements $|V_{rs}|$, the lepton CKM matrix elements $|U_{rs}|$, and the second
generation masses $m_c, m_s, m_\mu$. This means, in particular, that it gives
near maximal mixing $U_{\mu3}$ between $\nu_\mu$ and $\nu_\tau$ as observed by
SuperKamiokande, Kamiokande and Soudan, while keeping small the corresponding
quark angles $V_{cb}, V_{ts}$. In addition, the scheme gives (i) rough
order-of-magnitude estimates for the masses of the lowest generation, (ii)
predictions for low energy FCNC effects such as $K_L \to e \mu$, (iii) a
possible explanation for the long-standing puzzle of air showers beyond the GZK
cut-off. All these together, however, still represent but a portion of the
possible physical consequences derivable from the DSM scheme the majority of
which are yet to be explored. | hep-ph |
NOvA and T2K: The race for the neutrino mass hierarchy: The determination of the ordering of the neutrino masses (the hierarchy) is
probably a crucial prerequisite to understand the origin of lepton masses and
mixings and to establish their relationship to the analogous properties in the
quark sector. Here, we follow an alternative strategy to the usual
neutrino--antineutrino comparison in long baseline neutrino oscillation
experiments: we exploit the combination of the neutrino-only data from the NOvA
and the T2K experiments by performing these two off-axis experiments at
different distances but at the same $<E >/L$, where $<E >$ is the mean neutrino
energy and $L$ is the baseline. This would require a minor adjustment to the
proposed off-axis angle for one or both of the proposed experiments. | hep-ph |
A rotating string model versus baryon spectra: We continue our program of describing hadrons as rotating strings with
massive endpoints. In this paper we propose models of baryons and confront them
with the baryon Regge trajectories. We show that these are best fitted by a
model of a single string with a quark at one endpoint and a diquark at the
other. This model is preferred over the Y-shaped string model with a quark at
each endpoint. We show how the model follows from a stringy model of the
holographic baryon which includes a baryonic vertex connected with N_c strings
to flavor probe branes. From fitting to baryonic data we find that there is no
clear evidence for a non-zero baryonic vertex mass, but if there is such a mass
it should be located at one of the string endpoints. The available baryon
trajectories in the angular momentum plane (J,M^2), involving light, strange,
and charmed baryons, are rather well fitted when adding masses to the string
endpoints, with a single universal slope of 0.95 GeV^-2. Most of the results
for the quark masses are then found to be consistent with the results extracted
from the meson spectra in a preceding paper, where the value of the slope
emerging from the meson fits was found to be 0.90 GeV^-2. In the plane of
quantum radial excitations, (n,M^2), we also find a good agreement between the
meson and baryon slopes. The flavor structure of the diquark is examined, where
our interest lies in particular on baryons composed of more than one quark
heavier than the u and d quarks. For these baryons we present a method of
checking the holographic interpretation of our results. | hep-ph |
Quark-Lepton Mass Relation and CKM mixing in an A4 Extension of the
Minimal Supersymmetric Standard Model: An interesting mass relation between down type quarks and charged leptons has
been recently predicted within a supersymmetric SU(3)_c \times SU(2)_L \times
U(1)_Y model based on the A4 flavor symmetry. Here we propose a simple
extension which provides an adequate full description of the quark sector. By
adding a pair of vector-like up-quarks we show how the CKM entries Vub, Vcb,
Vtd and Vts arise from deviations of the unitarity. We perform an analysis
including the most relevant observables in the quark sector, such as
oscillations and rare decays of Kaons, Bd and Bs mesons. In the lepton sector,
model predicts an inverted hierarchy for the neutrino masses leading to a
potentially observable rate of neutrinoless double beta decay. | hep-ph |
Implementing the exact kinematical constraint in the saturation
formalism: We revisit the issue of the large negative next-to-leading order (NLO) cross
section for single inclusive hadron production in $pA$ collisions in the
saturation formalism. By implementing the exact kinematical constraint in the
modified dipole splitting functions, two additional positive NLO correction
terms are obtained. In the asymptotic large $k_\perp$ limit, we analytically
show that these two terms become as large as the negative NLO contributions
found in our previous calculation. Furthermore, the numerical results
demonstrate that the applicable regime of the saturation formalism can be
extended to a larger $k_\perp$ window, where the exact matching between the
saturation formalism (in the asymptotic $k_\perp$ regime) and the collinear
factorization calculations will have to be performed separately. In addition,
after significantly improving the numerical accuracy of the NLO correction, we
obtain excellent agreement with the LHC and RHIC data for forward hadron
productions. | hep-ph |
Data Unfolding in W mass measurements at LEP2: The use of an unfolding procedure is proposed as an alternative method of
extracting the $W$ boson mass from the data measured at LEP2, which may improve
the accuracy of this measurement. The benefits of the direct unfolding method
based on the Singular Value Decomposition of the response matrix are
demonstrated on the example of W mass determination from the charged lepton
energy spectra. | hep-ph |
Charm and Bottom Quark Masses from Perturbative QCD: Using a new result for the first moment of the hadronic production cross
section at order ${\cal O}(\alpha_s^3)$, and new data on the $J/\psi$ and
$\psi'$ resonances for the charm quark, we determine the \msb masses of the
charm and bottom quarks to be $\bar{m}_c(\bar{m}_c) = 1.295 \pm 0.015$ GeV and
$\bar{m}_b(\bar{m}_b) = 4.205 \pm 0.058$ GeV. We assume that the continuum
contribution to the sum rules is adequately described by pQCD. While we observe
a large reduction of the perturbative error, the shifts induced by the
theoretical input are very small. The main change in the central value of $m_c$
is related to the experimental data. On the other hand, the value of $m_b$ is
not changed by our calculation to the assumed precision. | hep-ph |
Jet grooming through reinforcement learning: We introduce a novel implementation of a reinforcement learning (RL)
algorithm which is designed to find an optimal jet grooming strategy, a
critical tool for collider experiments. The RL agent is trained with a reward
function constructed to optimize the resulting jet properties, using both
signal and background samples in a simultaneous multi-level training. We show
that the grooming algorithm derived from the deep RL agent can match
state-of-the-art techniques used at the Large Hadron Collider, resulting in
improved mass resolution for boosted objects. Given a suitable reward function,
the agent learns how to train a policy which optimally removes soft wide-angle
radiation, allowing for a modular grooming technique that can be applied in a
wide range of contexts. These results are accessible through the corresponding
GroomRL framework. | hep-ph |
Large Neutrino Mixing in Grand Unified Theories: A non-minimal, semi-realistic version of supersymmetric SU(5) grand unified
theory is discussed. The solution of the doublet-triplet splitting problem
leads to a better agreement between the predicted and observed values of the
low-energy strong coupling constant and to a prolongation of the proton
lifetime. A U(1) flavor symmetry allows to accommodate a realistic mass
spectrum in the charged and in the neutral fermion sectors and protects
doublet-triplet splitting and proton decay from dangerous radiative corrections
or non-renormalizable operators. | hep-ph |
Oblique corrections from less-Higgsless models in warped space: The Higgsless model in warped extra dimension is reexamined. Dirichlet
boundary conditions on the TeV brane are replaced with Robin boundary
conditions which are parameterized by a mass parameter $M$. We calculate the
Peskin-Takeuchi precision parameters $S$, $T$ and $U$ at tree level. We find
that to satisfy the constraints on the precision parameters at $99 \%$ [$95
\%$] confidence level (CL) the first Kaluza-Klein excited $Z$ boson, $Z'$,
should be heavier than 5 TeV [8 TeV]. The Magnitude of $M$, which is infinitely
large in the original model, should be smaller than 200 GeV (70 GeV) for the
curvature of the warped space $R^{-1}=10^{16}$ GeV ($10^{8}$ GeV) at $95\%$ CL.
If the Robin boundary conditions are induced by the mass terms localized on the
TeV brane, from the $99\%$ [$95\%$] bound we find that the brane mass
interactions account for more than $97\%$ [$99\%$] of the masses of $Z$ and $W$
bosons. Such a brane mass term is naturally interpreted as a vacuum expectation
value of the Higgs scalar field in the standard model localized on the TeV
brane. If so, the model can be tested by precise measurements of $HWW$, $HZZ$
couplings and search for 1st Kaluza-Klein excited states. | hep-ph |
Radiative Decays, Nonet Symmetry and SU(3) Breaking: We re-examine the problem of simultaneously describing in a consistent way
all radiative and leptonic decays of light mesons (V -> P gamma, P -> V gamma,
P -> gamma gamma, V -> e^+ e^-). For this purpose, we rely on the Hidden Local
Symmetry model in both its anomalous and non--anomalous sectors. We show that
the SU(3) symmetry breaking scheme proposed by Bando, Kugo and Yamawaki,
supplemented with nonet symmetry breaking in the pseudoscalar sector, allows
one to reach a nice agreement with all data, except for the K^{*+/-} radiative
decay. An extension of this breaking pattern allows one to account for this
particular decay mode too. Considered together, the whole set of radiative
decays provides a pseudoscalar mixing angle theta_P ~ -11^o and a value for
theta_V which is ~ 3^o from that of ideal mixing. We also show that it is
impossible, in a practical sense, to disentangle the effects of nonet symmetry
breaking and those of glue inside the eta', using only light meson decays. | hep-ph |
Proton-antiproton annihilation into massive leptons: We extend previous calculations of polarization observables for the
annihilation reaction $\bar p +p\to \ell^{-}+\ell^{+}$ to the case of heavy
leptons, such as the $\tau$-lepton. We consider the case when the beam and/or
the target are polarized, as well as the polarization of the outgoing leptons.
We give the dependence of the unpolarized cross section, angular asymmetry, and
various polarization observables on the relevant kinematical variables in the
center of mass and in the laboratory system, with particular attention to the
effect of the mass induced terms. | hep-ph |
Recent developments on direct $CP$ violation in the kaon system and
connection to $K \to πν\barν$ measurements: The first lattice result from the RBC and UKQCD Collaborations and improved
perturbative calculations of $\varepsilon^{\prime}_K / \varepsilon_K$ have
implied that the Standard-Model (SM) expectation deviates from measured values
at the $2.8\,\sigma$ level. Since $\varepsilon^{\prime}_K / \varepsilon_K$
comes from $CP$-violating FCNC and is significantly suppressed in the SM, the
discrepancy can be explained easily in several new physics (NP) models. In this
contribution, it is shown that correlations with the other rare decays,
especially $K\to \pi \nu \overline{\nu}$ and $K_S \to \mu^+ \mu^-$, are crucial
for discrimination of the NP models. These channels can be probed precisely in
the future by the NA62 and KOTO experiments for $K\to \pi \nu \overline{\nu}$
and LHCb experiment for $K_S \to \mu^+ \mu^-$. | hep-ph |
Revisiting constraints on 3+1 active-sterile neutrino mixing using
IceCube data: Recent IceCube search results for sterile neutrino increased tension between
the combined appearance and disappearance experiments. On the other hand,
MiniBooNE latest data confirms at $4.9\sigma$ CL the short-baseline oscillation
anomaly. We analyze published IceCube data based on two different
active-sterile mixing schemes using one additional sterile neutrino flavor. We
present exclusion regions in the parameter ranges $0.01 \le \sin^2 \theta_{24}
\le 0.1$ and $0.1~{\rm eV}^2 \le \Delta m^2_{42} \le 10~{\rm eV}^2$ for the
mass-mixing and flavor-mixing schemes. Under the more conservative mass-mixing
scheme, $3\sigma$ CL allowed regions for the appearance experiment and
MiniBooNE latest result are excluded at $\gtrsim 3\sigma$ CL. In case of
less-restrictive flavor-mixing scheme, results from the appearance experiments
are excluded at $\gtrsim 2\sigma$ CL. We also find that including prompt
component of the atmospheric neutrino flux relaxes constraints on sterile
mixing for $\Delta m^2_{42} \gtrsim 1~{\rm eV}^2$. | hep-ph |
Beyond The Standard Model: This Time for Real: The value of the neutrino mass reported by the SuperK collaboration fits
beautifully into the framework of gauge theory unification. Here I justify this
claim, and review the other main reasons to believe in that framework.
Supersymmetry and SO(10) symmetry are important ingredients; nucleon
instability is a dramatic consequence. | hep-ph |
From Cosmic Inflation and Matter Creation to Dark Matter -- Journey of
the Inflaton?: A scenario of the inflaton evolution from cosmic inflation and matter
creation to dark matter/dark energy today is presented. To start with, a model
of the inflationary phase of the inflaton is introduced. The inflaton rolls
down a hilltop potential along with matter creation being dragged down by the
presence of matter. Presence of matter provides a mechanism to stop universe's
acceleration and hence the inflationary phase. The model predictions for the
standard metrics are fully consistent with the current CMB limits. The
potential could in principle be extended to complete a potential hill
subsequent to inflation. The evolution of the inflaton from the inflationary
phase to radiation/matter dominated eras and to current times can be inferred
qualitatively following the evolution of its equation of state parameter.
Existence of solutions to its dynamics, tracking matter as it evolves to
current times, provides a plausible reasoning for the relative order of
magnitudes of the cosmological parameters, in particular to the relative
abundance of dark matter today. | hep-ph |
Phenomenology of epsilon_K in the top era: Todays key information on the shape of the unitarity triangle is obtained
from the well-measured quantity epsilon_K characterizing the CP-violation in
|Delta S|=2 transitions. The phenomenological analysis requires the input of
four key quantities: The magnitudes of the CKM elements V_cb and V_ub, the top
quark mass and the non-perturbative parameter B_K. In the recent years all of
them have been determined with increasing precision. In order to keep up with
this progress the |Delta S|=2-hamiltonian had to be obtained in the
next-to-leading order (NLO) of renormalization group improved perturbation
theory. I present the NLO results for the QCD coefficients eta_1 and eta_3,
which have been calculated by Stefan Herrlich and myself, and briefly sketch
some aspects of the calculation. Then I give an update of the Unitarity
Triangle using the summer 1996 data for the input parameters. The results for
the improved Wolfenstein parameters rho-bar and eta-bar and the CKM phase delta
are -0.21 < rho-bar < 0.22, 0.27 < eta-bar < 0.43 and 57 degrees < delta < 122
degrees. The range for the quantity sin(2 beta) entering CP asymmetries in
B-decays is found as 0.46 < sin(2 beta) < 0.79. The given ranges correspond to
one standard deviation in the input parameters. Finally I briefly discuss the
K_L-K_S mass difference. | hep-ph |
The Higgs sector of the complex MSSM at two-loop order: QCD
contributions: Results are presented for the leading two-loop contributions of O(alpha_t
alpha_s) to the masses and mixing effects in the Higgs sector of the MSSM with
complex parameters. They are obtained in the Feynman-diagrammatic approach
using on-shell renormalization. The full dependence on all complex phases is
taken into account. The renormalization of the appropriate contributions of the
Higgs-boson sector and the scalar top and bottom sector is discussed. Our
numerical analysis for the lightest MSSM Higgs-boson mass is based on the new
two-loop corrections, supplemented by the full one-loop result. The corrections
induced by the phase variation in the scalar top sector are enhanced by the
two-loop contributions. We find that the corresponding shift in M_h1 can amount
to 5 GeV. | hep-ph |
Hard Diffraction in Pythia 8: We present an overview of the options for diffraction implemented in the
general--purpose event generator Pythia 8. We review the existing model for
low-- and high--mass soft diffraction and present a new model for hard
diffraction in pp and ppbar collisions. Both models uses the Pomeron approach
pioneered by Ingelman and Schlein, factorising the single diffractive cross
section into a Pomeron flux and a Pomeron PDF. The model for hard diffraction
is implemented as a part of the multiparton interactions framework, thereby
introducing a dynamical rapidity gap survival probability that explicitly
breaks factorisation. | hep-ph |
CGC predictions for p+A collisions at the LHC and signature of QCD
saturation: We present various predictions for the upcoming p+Pb collisions at \sqrt{S}=5
TeV within the color glass condensate (CGC) formalism, including single
inclusive charged hadron production, single inclusive prompt photon production,
direct photon production, charged hadron multiplicity distribution and
photon-hadron azimuthal correlations. Using the running-coupling
Balitsky-Kovchegov evolution equation for calculating various observables, we
show that the main source of uncertainties is due to less constrained initial
nuclear saturation scale. This gives rise to rather large theoretical
uncertainties for nuclear modification factor R_{pA} at the LHC. Nevertheless,
we propose a simple scheme in which one can still test the main dynamics of the
CGC/saturation in p+A collisions at the LHC. | hep-ph |
Finding the CP-Violating Higgs Bosons at e^+e^- Colliders: We discuss a general two-Higgs-doublet model with CP violation in the Higgs
sector. In general, the three neutral Higgs fields of the model all mix and the
resulting physical Higgs bosons have no definite CP properties. We derive a new
sum rule relating Yukawa and Higgs-Z couplings which implies that a neutral
Higgs boson cannot escape detection at an e^+e^- collider if it is
kinematically accessible in Z+Higgs, $b\anti b+$Higgs and $t\anti t+$Higgs
production, irrespective of the mixing angles and the masses of the other
neutral Higgs bosons. We also discuss modifications of the sum rules and their
phenomenological consequences in the case when the two-doublet Higgs sector is
extended by adding one or more singlets. | hep-ph |
Study of Single W production in e-gamma collisions through the decay
lepton spectrum to probe gamma-WW couplings: We investigate the effect of anomalous gamma-W-W couplings in e-gamma --> nu
W through the angular and energy spectrum of the secondary leptons. Within the
narrow-width approximation, a semi-analytical study of the secondary lepton
energy-angle double distribution is considered. Utility of observables derived
from this is demonstrated by considering the anomalous coupling,
delta-kappa-gamma. Results of our investigation for typical ILC machine
considered at Ecm = 300-1000 GeV re-affirms potential of this collider as a
precision machine. | hep-ph |
Complementarity of $B\to K^{(*)} μ\bar μ$ and $B\to K^{(*)} +
\mathrm{inv}$ for searches of GeV-scale Higgs-like scalars: The rare decays $B^+\to K^+ \mu\bar \mu$ and $B^0\to K^{*0} \mu\bar\mu$
provide the strongest constraints on the mixing of a light scalar with the
Higgs boson for GeV-scale masses. The constraints sensitively depend on the
branching ratio to muons. Additional decay channels like an invisible partial
width may substantially weaken the constraints. This scenario will be probed at
Belle II in $B\to K^{(*)} + \mathrm{inv}$. We illustrate the complementarity of
scalar decays to muons and invisible decays using the currently available
results of LHCb and BaBar. We provide two simple model realisations providing a
sizeable invisible scalar width, one based on a real scalar and one based on a
$U(1)_{B-L}$ gauge symmetry. In both examples the scalar decays into heavy
neutral leptons which can be motivated by the seesaw mechanism for neutrino
masses. | hep-ph |
Physics Beyond the Standard Model: I present a brief overview of some exciting possibilities for physics Beyond
the Standard Model. I include short discussions of neutrino physics, the strong
CP problem and axions, GUTs, large and warped extra dimensions, Little Higgs
models and supersymmetry. The chances appear excellent that in the next few
years-- as the LHC era gets underway-- data from a bevy of experiments will
point the way to a new paradigm for the laws of physics as we know them. | hep-ph |
Matching between matrix elements and parton showers using a Leading-Log
subtraction method in NLO-QCD: A new method to construct event-generators based on next-to-leading order QCD
matrix-elements and leading-logarithmic parton showers is proposed. Matrix
elements of loop diagrams as well as those of a tree level can be generated
using an automatic system. A soft/collinear singularity is treated using a
leading-log subtraction method. Higher order re-summation of the soft/collinear
correction by the parton shower method is combined with the NLO matrix-element
without any double-counting in this method. | hep-ph |
Bi-large neutrino mixing from bilinear R-parity violation with
non-universality: We investigate how the bi-large mixing required by the recent neutrino data
can be accommodated in the supersymmetric standard model allowing bilinear
R-parity violation and non-universal soft terms. In this scheme, the tree-level
contribution and the so-called Grossman-Haber one-loop diagrams are two major
sources of the neutrino mass matrix. The relative size of these two
contributions falls into the right range to generate the atmospheric and solar
neutrino mass hierarchy. On the other hand, the bi-large mixing is typically
obtained by a mild tuning of input parameters to arrange a partial cancellation
among various contributions. | hep-ph |
CP violation in meson decays: This is a written version of a series of lectures aimed at graduate students
in the field of (theoretical and experimental) high energy physics. The main
topics covered are: (i) The flavor sector of the Standard Model and the
Kobayashi-Maskawa mechanism of CP violation; (ii) Formalism and theoretical
interpretation of CP violation in meson decays; (iii) K decays; (iv) D decays;
(v) B decays: b -> c c-bar s, b -> s s-bar s, b -> u u-bar d and b -> c u-bar
s, u c-bar s; (vi) CP violation as a probe of new physics and, in particular,
of supersymmetry. | hep-ph |
Distinguishing split supersymmetry in Higgs signals at the Large Hadron
Collider: We examine the possibility of detecting signals of split supersymmetry in the
loop-induced decay h --> gamma gamma of the Higgs boson at the Large Hadron
Collider, where charginos, as surviving light fermions of the supersymmetric
spectrum, can contribute in the loop. We perform a detailed study of
uncertainties in various parameters involved in the analysis, and thus the net
uncertainty in the standard model prediction of the rate. After a thorough scan
of the parameter space, taking all constraints into account, we conclude that
it will be very difficult to infer about split supersymmetry from Higgs signals
alone. | hep-ph |
Improved Intermittency Analysis of Single Event Data: The intermittency analysis of single event data (particle moments) in
multiparticle production is improved, taking into account corrections due to
the reconstruction of history of a particle cascade. This approach is tested
within the framework of the $\alpha$-model. | hep-ph |
Higgs production in association with a single top quark at the LHC: We present a detailed study of Higgs boson production in association with a
single top quark at the LHC, at next-to-leading order accuracy in QCD. We
consider total and differential cross sections, at the parton level as well as
by matching short distance events to parton showers, for both t-channel and
s-channel production. We provide predictions relevant for the LHC at 13 TeV
together with a thorough evaluation of the residual uncertainties coming from
scale variation, parton distributions, strong coupling constant and heavy quark
masses. In addition, for t-channel production, we compare results as obtained
in the 4-flavour and 5-flavour schemes, pinning down the most relevant
differences between them. Finally, we study the sensitivity to a
non-standard-model relative phase between the Higgs couplings to the top quark
and to the weak bosons. | hep-ph |
Two-loop perturbative corrections to the constrained effective potential
in thermal QCD: In this paper, we compute the constrained QCD effective potential up to
two-loop order with finite quark mass and chemical potential. We present the
explicit calculations by using the double line notation and analytical
expressions for massless quarks are obtained in terms of the Bernoulli
polynomials or Polyakov loops. Our results explicitly show that the constrained
QCD effective potential is independent on the gauge fixing parameter. In
addition, as compared to the massless case, the constrained QCD effective
potential with massive quarks develops a completely new term which is only
absent when the background field vanishes. Furthermore, we discuss the relation
between the one- and two-loop constrained effective potential. The surprisingly
simple proportionality that exists in the pure gauge theories, however, is in
general no longer true when fermions are taken into account. On the other hand,
for high baryon density $\mu_B$ and low temperature $T$, in the massless limit,
we do also find a similar proportionality between the one- and two-loop
fermionic contributions in the constrained effective potential up to ${\cal
O}(T/\mu_B)$. | hep-ph |
Single production of vector-like top partner decaying to $Wb$ in the
leptonic channel at $ep$ colliders in the LHT model: In the littlest Higgs model with T-parity(LHT), we study the single
production of vector-like top partner with the subsequent decay $T_{+}\to Wb$
in the leptonic channel at the $ep$ colliders. Focus on the LHeC ($ \sqrt{s} $
= 1.98 TeV) and FCC-eh ($ \sqrt{s} $ = 5.29 TeV), we investigate the
observability of the single top partner production with the unpolarized and
polarized electron beams, respectively. As a result, the statistical
significance can be enhanced by the polarized electron beams. Under the current
constraints, the search for $T_{+}$ in the $Wb$ channel at the LHeC cannot
provide a stronger limit on the top partner mass. By contrast, the search for
the $T_{+}$ in this channel at the FCC-eh with polarized $ e^- $ beams can
exclude the top partner mass up to 1350 GeV, 1500 GeV and 1565 GeV with
integrated luminosities of 100 fb$^{-1}$, 1000 fb$^{-1}$ and 3000 fb$^{-1}$ at
the 2$\sigma$ level, which is an improvement with respect to the current
indirect searches and the LHC direct searches. Furthermore, we also give an
extrapolation to the high-luminosity LHC with $\sqrt{s}=14$ TeV and $
L=3000~\rm{fb}^{-1} $. Our results show that the LHT model is still a natural
solution to the shortcomings of the electroweak and scalar sector although it
has been constrained severely. | hep-ph |
Comment on " a unified scheme for flavored mesons and baryons": We would comment on the results of the paper "a unified scheme for flavored
mesons and baryons" (P.C.Vinodkumar, J.N.Panandya, V.M.Bannur, and
S.B.Khadkikar Eur. Phys. J. A4(1999)83), and point out some inconsistencies and
mistakes in the work for solving the Dirac equation. In terms of an example for
a single particle we investigate the reliability of the perturbative method for
computing the Coulomb energy and discuss the contribution to the wavefunction
at origin from the Coulomb potential. We conclude that the accuracy of their
numerical results needs to be reconsidered. | hep-ph |
Radiative tritium beta-decay and the neutrino mass: The shape of the electron energy spectrum in 3H beta-decay permits a direct
assay of the absolute scale of the neutrino mass; a highly accurate theoretical
description of the electron energy spectrum is necessary to the empirical task.
We update Sirlin's calculation of the outer radiative correction to nuclear
beta-decay to take into account the non-zero energy resolution of the electron
detector. In previous 3H beta-decay studies the outer radiative corrections
were neglected all together; only Coulomb corrections to the spectrum were
included. This neglect artificially pushes m_nu^2 < 0 in a potentially
significant way. We present a computation of the theoretical spectrum
appropriate to the extraction of the neutrino mass in the sub-eV regime. | hep-ph |
Pentaquarks and Radially Excited Baryons: In this talk I report on a computation of the spectra of exotic pentaquarks
and radial excitations of the low--lying ${1/2}^+$ and ${3/2}^+$ baryons in a
chiral soliton model. | hep-ph |
Visible and dark matter from a first-order phase transition in a
baryon-symmetric universe: The similar cosmological abundances observed for visible and dark matter
suggest a common origin for both. By viewing the dark matter density as a
dark-sector asymmetry, mirroring the situation in the visible sector, we show
that the visible and dark matter asymmetries may have arisen simultaneously
through a first-order phase transition in the early universe. The dark
asymmetry can then be equal and opposite to the usual visible matter asymmetry,
leading to a universe that is symmetric with respect to a generalised baryon
number. We present both a general structure, and a precisely defined example of
a viable model of this type. In that example, the dark matter is atomic as well
as asymmetric, and various cosmological and astrophysical constraints are
derived. Testable consequences for colliders include a Z' boson that couples
through the B-L charge to the visible sector, but also decays invisibly to dark
sector particles. The additional scalar particles in the theory can mix with
the standard Higgs boson and provide other striking signatures. | hep-ph |
The electroweak chiral Lagrangian revisited: Using a manifestly gauge-invariant approach we show that the set of
low-energy constants in the electroweak chiral Lagrangian currently used in the
literature is redundant. In particular, by employing the equations of motion
for the gauge fields, one can choose to remove two low-energy constants which
contribute to the self-energies of the gauge bosons. The relation of this
result to the experimentally determined values for the oblique parameters S,T
and U is discussed. We then evaluate the matching relation between
gauge-invariant Green's functions in the full and the effective theory for the
case of the Standard Model with a heavy Higgs boson and compare the results for
the independent low-energy constants with those for a simple Technicolor model.
Since the pattern of the low-energy constants is very different in these two
models it may be misleading to mimic any strongly interacting symmetry breaking
sector by a heavy Higgs boson. From our investigation we conclude that current
electroweak precision data do not really rule out such strongly interacting
models. | hep-ph |
Searching for Charged Higgs Bosons via $e^+ e^- \to H^+ H^- \to c\bar{b}
\bar{c}b $ at Linear Colliders: We study a search for the charged Higgs boson via
$e^+e^- \to H^+H^- \to c\bar{b}\bar{c}b$ at the 500 GeV ILC. In a general two
Higgs doublet model without $Z_2$ symmetry, extra Yukawa couplings $\rho_{tt}$
and $\rho_{tc}$ can drive baryogenesis, but searches at the HL-LHC may still go
empty-handed if the couplings are relatively weak. Taking $m_{H^+ } \simeq m_H
\simeq m_A \simeq 200$ GeV, with $\rho_{tt}$, $\rho_{tc}\sim 0.1$ and no
$h(125)$-$H$ mixing, $H^+ \to c\bar b$ decay is dominant, and the
$c\bar{b}\bar{c}b$ final state is likely overwhelmed by QCD background at the
LHC. We show that the electroweak production of $H^+ H^-$ at the ILC is
discoverable with integrated luminosity of 1 ab$^{-1}$. Furthermore, we show
that $m_{H^+}$ can be extracted by requiring the two pairs of $b$ and light
jets be roughly equal in mass, without assuming the mass value. Thus, ILC can
probe low mass Higgs bosons in multijet final states to complement HL-LHC in
the future | hep-ph |
Effects of custodial symmetry breaking in the Georgi-Machacek model at
high energies: The model proposed by Georgi and Machacek enables the Higgs sector to involve
isospin triplet scalar fields while retaining a custodial $SU(2)_V$ symmetry in
the potential and thus ensuring the electroweak $\rho$ parameter to be one at
tree level. This custodial symmetry, however, is explicitly broken by loop
effects of the $U(1)_Y$ hypercharge gauge interaction. In order to make the
model consistent at high energies, we construct the most general form of the
Higgs potential without the custodial symmetry, and then we derive the one-loop
$\beta$-functions for all the model parameters. Assuming the $\delta_i$
quantities describing the custodial symmetry breaking to be zero at low energy,
we find that $|\delta_i|$ are typically smaller than the magnitude of the
$U(1)_Y$ gauge coupling and the other running parameters in the potential also
at high energy without spoiling perturbativity and vacuum stability. We also
clarify that the mass degeneracy among the $SU(2)_V$ 5-plet and 3-plet Higgs
bosons is smoothly broken by $\sim 0.1\%$ corrections. These results show that
the amount of the custodial symmetry breaking is well kept under control up to
energies close to the theory cutoff. | hep-ph |
Probing the long-range structure of the $T_{cc}^+$ with the strong and
electromagnetic decays: Very recently, the LHCb Collaboration reported the doubly charmed tetraquark
state $T_{cc}^+$ below the $D^{*+}D^0$ threshold about $273$ keV. As a very
near-threshold state, its long-distance structure is very important. In the
molecular scheme, we relate the coupling constants of $T_{cc}^+$ with
$D^{*0}D^+$ and $D^{*+}D^0$ to its binding energy and mixing angle of two
components with a coupled-channel effective field theory. With the coupling
constants, we investigate the kinetically allowed strong decays $T_{cc}^+\to
D^0D^0\pi^+$, $T_{cc}^+\to D^+D^0\pi^0$ and radiative decays $D^+D^0 \gamma$.
Our results show that the decay width of $T_{cc}^+\to D^0D^0\pi^+$ is the
largest one, which is just the experimental observation channel. Our
theoretical total strong and radiative widths are in favor of the $T_{cc}^+$ as
a $|D^{*+}D^0\rangle$ dominated bound state. The total strong and radiative
width in the single channel limit and isospin singlet limit are given as
$59.7^{+4.6}_{-4.4} \text{ keV}$ and $46.7^{+2.7}_{-2.9} \text{ keV}$,
respectively. Our calculation is cutoff-independent and without prior isospin
assignment. The absolute partial widths and ratios of the different decay
channels can be used to test the structure of $T_{cc}^+$ state when the updated
experimental results are available. | hep-ph |
Effective kinetic description of the expanding overoccupied Glasma: We report on a numerical study of the Boltzmann equation including
$2\leftrightarrow 2$ scatterings of gluons and quarks in an overoccupied Glasma
undergoing longitudinal expansion. We find that when a cascade of gluon number
to the infrared occurs, corresponding to an infrared enhancement analogous to a
transient Bose-Einstein condensate, gluon distributions qualitatively reproduce
the results of classical-statistical simulations for the expanding Glasma.
These include key features of the distributions that are not anticipated in the
"bottom-up" thermalization scenario. We also find that quark distributions,
like those of gluons, satisfy self-similar scaling distributions in the
overoccupied Glasma. We discuss the implications of these results for a deeper
understanding of the self-similarity and universality of parton distributions
in the Glasma. | hep-ph |
Chiral Magnetic Effect in Isobaric Collisions from Anomalous-Viscous
Fluid Dynamics (AVFD): The isobaric collision experiment at RHIC provides the unique opportunity to
detect the possible signal of Chiral Magnetic Effect (CME) in heavy ion
collisions. The idea is to contrast the correlation observables of the two
colliding systems that supposedly have identical flow-driven background
contributions while quite different CME signal contributions due to the 10%
variation in their nuclear charge and thus magnetic field strength. With the
recently developed quantitative simulation tool for computing CME signal, the
Anomalous-Viscous Fluid Dynamics (AVFD), we demonstrate that a joint
(multiplicity + elliptic-flow) event selection is crucial for this purpose. We
further propose to use the absolute difference between RuRu and ZrZr events
(after using identical event selection) for detecting CME signal and make
predictions for the correlation observables. | hep-ph |
Light-Quark, Heavy-Quark Systems: An Update: We review many of the recently developed applications of Heavy Quark
Effective Theory techniques. After a brief update on Luke's theorem, we
describe striking relations between heavy baryon form factors, and how to use
them to estimate the accuracy of the extraction of $|V_{cb}|$. We discuss
factorization and compare with experiment. An elementary presentation, with
sample applications, of reparametrization invariance comes next. The final and
most extensive chapter in this review deals with phenomenological lagrangians
that incorporate heavy-quark spin-flavor as well as light quark chiral
symmetries. We compile many interesting results and discuss the validity of the
calculations. | hep-ph |
Correct $Δm^2_{ij}$ Dependence for Neutrino Oscillation Formulae: The time translation operator for neutrino mass states is often taken to be
$e^{-iEt/\hbar}$. This is not relativistically invariant. In kaon mixing,
physicists use $e^{-imc^2\tau/\hbar}$ where $\tau$ is the proper time of the
kaon state. The factor $mc^2\tau$ is the rest frame value of the four vector
product $p_\mu x^\mu$ which is an invariant quantity. If $-i p_\mu x^\mu$ is
used in neutrino oscillation formulae instead of $-iEt$, the scale of the
$\Delta m^2_{ij}$ is reduced by a factor of two. | hep-ph |
Large $\mathbf{b}$ behaviour in the CGC/saturation approach: BFKL
equation with pion loops: In this paper we proposed a solution to the longstanding problem of the
CGC/saturation approach: the power-like fall of the scattering amplitudes at
large $b$. This decrease leads to the violation of the Froissart theorem and
makes the approach theoretically inconsistent. We showed in the paper that sum
of the pion loops results in the exponential fall of the scattering amplitude
at large impact parameters and in the restoration of the Froissart theorem. | hep-ph |
Probing hyperon CP violation from charmed baryon decays: CP violation (CPV) in the baryon sectors has not yet been established
experimentally. In this work, we propose to search for the hyperon CPV through
the Cabibbo-favored charm-baryon decaying processes involving a hyperon in the
final states, such as $\Lambda_c^+\to \Lambda^0\pi^+, \Lambda^0\to p\pi^-$. The
CPV of the hyperon decays are purely revealed in these chain processes, since
the CPV in the Cabibbo-favored charm decays are vanishing in the Standard Model
(SM). The hyperons are polarized in the weak charm decays, so that we can
measure the Lee-Yang asymmetric parameter $\alpha$ by the angular
distributions, and then can measure the $\alpha$-induced CPV. It can be found
that it is accessible for Belle II and LHCb to reach the SM prediction of the
hyperon CPV in the near future. | hep-ph |
Photoproduction of the charged charmoniumlike $Z_{c}^{+}(4200)$: In this work, inspired by the observation of charmoniumlike
$Z_{c}^{+}(4200)$% , we study the photoproduction of charged charmoniumlike
$Z_{c}^{+}(4200)$ with an effective Lagrangian approach and the Regge
trajectories model. The numerical results indicate that the Reggeized treatment
can lead to a lower total cross section of the $Z_{c}^{+}(4200)$
photoproduction and the peak position of cross section was moved to the higher
energy point when the Reggeized treatment was added. {Moreover, using the data
from the COMPASS experiment and presented theoretical predictions, an upper
limit of the decay width of $Z_{c}(4200)\rightarrow J/\psi \pi $ is estimated.}
The relevant results not only shed light on the further experiment of searching
for the charmoniumlike $Z_{c}(4200)$ state via meson photoproduction, but also
provide valuable informations for having a better comprehension of the nature
of charmoniumlike $Z_{c}(4200)$ state. | hep-ph |
SMEFT analysis of vector boson scattering and diboson data from the LHC
Run II: We present a systematic interpretation of vector boson scattering (VBS) and
diboson measurements from the LHC in the framework of the dimension-six
Standard Model Effective Field Theory (SMEFT). We consider all available
measurements of VBS fiducial cross-sections and differential distributions from
ATLAS and CMS, in most cases based on the full Run II luminosity, and use them
to constrain 16 independent directions in the dimension-six EFT parameter
space. Compared to the diboson measurements, we find that VBS provides
complementary information on several of the operators relevant for the
description of the electroweak sector. We also quantify the ultimate EFT reach
of VBS measurements via dedicated projections for the High Luminosity LHC. Our
results motivate the integration of VBS processes in future global SMEFT
interpretations of particle physics data. | hep-ph |
Color confinement from fluctuating topology: QCD possesses a compact gauge group, and this implies a non-trivial
topological structure of the vacuum. In this contribution to the Gribov-85
Memorial volume, we first discuss the origin of Gribov copies and their
interpretation in terms of fluctuating topology in the QCD vacuum. We then
describe the recent work with E. Levin that links the confinement of gluons and
color screening to the fluctuating topology, and discuss implications for spin
physics, high energy scattering, and the physics of quark-gluon plasma. | hep-ph |
Proposal and theoretical formalism for studying baryon radiative decays
from J/ψ\to B^*\bar B + \bar{B^*}B \to γB\bar B: With accumulation of high statistics data at BESIII, one may study many new
interesting channels. Among them, J/\psi \to B^*\bar B + \bar{B^*}B \to \gamma
B\bar B processes may provide valuable information of the radiative decays of
the excited baryons (N^*,\Lambda^*,\Sigma^*,\Xi^*), and may shed light on their
internal quark-gluon structure. Our estimation for the branching ratios of the
nucleon excitations N^*(1440), N^*(1535) and N^*(1520) from the reaction J/\psi
\to N^*\bar p + \bar N^* p \to \gamma p\bar p, indicates that these processes
can be studied at BESIII with 10^{10} J/\psi events. Explicit theoretical
formulae for the partial wave analysis (PWA) of the J/\psi \to B^*\bar B +\bar
B^* B with B^*\to B \gamma and \bar B^*\to \bar B\gamma within covariant L-S
Scheme are provided. | hep-ph |
Technicolor Enhancement of $t \bar{t}$ Production at TeV-Colliders: It is shown that a technicolor theory containing a color-octet technipion,
usually denoted by $P^{0'}_{8}$, will give rise to an enhancement of $t \bar t$
production at the Tevatron, LHC and SSC, via the process $gg \rightarrow
P^{0'}_{8} \rightarrow t \bar t$. The relevant cross-sections are computed
taking into account the large lower bound on the top mass coming from the "top
search" experiments at LEP and CDF.
At the LHC and SSC, the signal is found to be comparable to the QCD
background, making the process quite accesible. | hep-ph |
Concerning pion parton distributions: Analyses of the pion valence-quark distribution function (DF),
${u}^\pi(x;\zeta)$, which explicitly incorporate the behaviour of the pion wave
function prescribed by quantum chromodynamics (QCD), predict ${u}^\pi(x\simeq
1;\zeta) \sim (1-x)^{\beta(\zeta)}$, $\beta(\zeta \gtrsim m_p)>2$, where $m_p$
is the proton mass. Nevertheless, more than forty years after the first
experiment to collect data suitable for extracting the $x\simeq 1$ behaviour of
${u}^\pi$, the empirical status remains uncertain because some methods used to
fit existing data return a result for ${u}^\pi$ that violates this constraint.
Such disagreement entails one of the following conclusions: the analysis
concerned is incomplete; not all data being considered are a true expression of
qualities intrinsic to the pion; or QCD, as it is currently understood, is not
the theory of strong interactions. New, precise data are necessary before a
final conclusion is possible. In developing these positions, we exploit a
single proposition, viz. there is an effective charge which defines an
evolution scheme for parton DFs that is all-orders exact. This proposition has
numerous corollaries, which can be used to test the character of any DF,
whether fitted or calculated. | hep-ph |
Quark sector of S3 models: classification and comparison with
experimental data: S3 models offer a low energy approach to describe the observed pattern of
masses and mixing, of both quarks and leptons. In this work, we first revisit
an S3 model with only one Higgs electroweak doublet, where the flavour symmetry
must be broken in order to produce an acceptable pattern of masses and mixing
for fermions. Then, we analyse different S3 models, where the flavour symmetry
is preserved as an exact, but hidden symmetry of the low energy spectra, after
the electroweak symmetry breaking. The latter models require the addition of
two more Higgs electroweak doublets which are accommodated in an S3 doublet. We
also explore the consequences of adding a fourth Higgs electroweak doublet,
thus occupying all three irreducible representations of S3. We show how the
various S3-invariant mass matrices of the different models can reproduce the
two texture zeroes and Nearest Neighbour Interaction matrix forms, which have
been found to provide a viable and universal treatment of mixing for both
quarks and leptons. We also find analytical and exact expressions for the CKM
matrix of the models in terms of quark mass ratios. Finally, we compare the
expressions of the CKM matrix of the different S3 models with the most up to
date values of masses and mixing in the quark sector, via a chi^2 analysis. We
find that the analytical expressions we derived reproduce remarkably well the
most recent experimental data of the CKM matrix, suggesting that S3 is a
symmetry of the quark sector. | hep-ph |
Axial Vector $cc$ and $bb$ Diquark Masses from QCD Laplace Sum-Rules: Constituent mass predictions for axial vector (i.e., $J^P=1^+$) $cc$ and $bb$
colour antitriplet diquarks are generated using QCD Laplace sum-rules. We
calculate the diquark correlator within the operator product expansion to NLO,
including terms proportional to the four- and six-dimensional gluon and
six-dimensional quark condensates. The sum-rules analyses stabilize, and we
find that the mass of the $cc$ diquark is 3.51~GeV and the mass of the $bb$
diquark is 8.67~GeV. Using these diquark masses as inputs, we calculate several
tetraquark masses within the Type-II diquark-antidiquark tetraquark model. | hep-ph |
Reduction of the proton radius discrepancy by 3 sigma: We show that in previous analyses of electron-proton scattering, the
uncertainties in the statistical procedure to extract the proton charge radius
are underestimated. Using a fit function based on a conformal mapping, we can
describe the scattering data with high precision and extract a radius value in
agreement with the one obtained from muonic hydrogen. | hep-ph |
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