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Masses and Mixing of $c q \bar{q} \bar{q}$ Tetraquarks Using
Glozman-Riska Hyperfine Interaction: In this paper we perform a detailed study of the masses and mixing of the
single charmed scalar tetraquarks: $c q \bar{q} \bar{q}$. We also give a
systematic analysis of these tetraquark states by weight diagrams, quantum
numbers and flavor wave functions. Tetraquark masses are calculated using four
different fits. The following SU(3)$_\mathrm{F}$ representations are discussed:
$\bar{15}_\mathrm{S}$, $\bar{3}_\mathrm{S}$, $6_\mathrm{A}$ and
$\bar{3}_\mathrm{A}$. We use the flavor-spin Glozman-Riska interaction
Hamiltonian with SU(3) flavor symmetry breaking. There are 27 different
tetraquarks composed of a charm quark $c$ and of the three light flavors $u, d,
s$: 11 cryptoexotic (3 D$_\mathrm{s}^{+}$, 4 D$^{+}$, 4 D$^{0}$) and 16
explicit exotic states. We discuss D$_\mathrm{s}$ and its isospin partners in
the same multiplet, as well as all the other four-quark states. Some explicit
exotic states appear in the spectrum with the same masses as
D$_\mathrm{s}^{+}$(2632) in $\bar{15}_\mathrm{S}$ and with the same masses as
D$_\mathrm{s}^{+}$(2317) in $6_\mathrm{A}$ representation, which confirm the
tetraquark nature of these states. | hep-ph |
Non-Abelian Discrete Flavor Symmetries from Magnetized/Intersecting
Brane Models: We study non-abelian discrete flavor symmetries, which can appear in
magnetized brane models. For example, $D_4$, $\Delta(27)$ and $\Delta(54)$ can
appear and matter fields with several representations can appear. We also study
the orbifold background, where non-abelian flavor symmetries are broken in a
certain way. | hep-ph |
Super-leading logarithms in non-global observables in QCD: Colour basis
independent calculation: In a previous paper we reported the discovery of super-leading logarithmic
terms in a non-global QCD observable. In this short update we recalculate the
first super-leading logarithmic contribution to the 'gaps between jets'
cross-section using a colour basis independent notation. This sheds light on
the structure and origin of the super-leading terms and allows them to be
calculated for gluon scattering processes for the first time. | hep-ph |
Precise predictions for mt, Vcb and tan: The fermion mass and mixing angle predictions of a recently proposed
framework are investigated for large b and $\tau$ Yukawa couplings. A new
allowed region of parameters is found for this large $\tan \beta$ case. The two
predictions which are substantially altered, $m_t$ and $\tan \beta$, are
displayed, including the dependence on the inputs $|V_{cb}|$, $m_c$, $m_b$ and
$\alpha_s$. A simple restriction on this framework yields an additional
prediction, for $|V_{cb}|$. If the b,t, and $\tau$ Yukawas are equal at the GUT
scale then $|\Vcb|$ is predicted and the top quark mass is constrained to lie
in the range $\mt = 179. \pm 4.$ GeV. | hep-ph |
Light axial-vector tetraquark state candidate: $a_1(1420)$: In this article, we study the axial-vector tetraquark state and
two-quark-tetraquark mixed state consist of light quarks using the QCD sum
rules. The present predictions disfavor assigning the $a_1(1420)$ as the
axial-vector tetraquark state with $J^{PC}=1^{++}$, while support assigning the
$a_1(1420)$ as the axial-vector two-quark-tetraquark mixed state. | hep-ph |
Energy dependence of underlying-event observables from RHIC to LHC
energies: A study of the charged-particle density (number density) in the transverse
region of the di-hadron correlations exploiting the existing pp and p$\bar{\rm
p}$ data from RHIC to LHC energies is reported. This region has contributions
from the Underlying Event (UE) as well as from Initial- and Final-State
Radiation (ISR-FSR). Based on the data, a two-component model is built. This
has the functional form $\propto s^{\alpha}+\beta\log(s)$, where the
logarithmic (($\beta = 0.140 \pm 0.007$)) and the power-law ($\alpha = 0.270
\pm 0.005$) terms describe the components more sensitive to the ISR-FSR and UE
contributions, respectively. The model describes the data from RHIC to LHC
energies, the extrapolation to higher energies indicates that at around
$\sqrt{s} \approx 100$\,TeV the number density associated to UE will match that
from ISR-FSR. Although this behaviour is not predicted by PYTHIA~8.244, the
power-law behaviour of the UE contribution is consistent with the energy
dependence of the parameter that regulates Multiparton Interactions. Using
simulations, KNO-like scaling properties of the multiplicity distributions in
the regions sensitive to either UE or ISR-FSR are also discussed. The results
presented here can be helpful to constrain QCD-inspired Monte Carlo models at
the Future Circular Collider energies, as well as to characterize the UE-based
event classifiers which are currently used at the LHC. | 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 |
Spectrum-doubled Heavy Vector Bosons at the LHC: We study a simple effective field theory incorporating six heavy vector
bosons together with the standard-model field content. The new particles
preserve custodial symmetry as well as an approximate left-right parity
symmetry. The enhanced symmetry of the model allows it to satisfy precision
electroweak constraints and bounds from Higgs physics in a regime where all the
couplings are perturbative and where the amount of fine-tuning is comparable to
that in the standard model itself.
We find that the model could explain the recently observed excesses in
di-boson processes at invariant mass close to 2 TeV from LHC Run 1 for a range
of allowed parameter space. The masses of all the particles differ by no more
than roughly 10%. In a portion of the allowed parameter space only one of the
new particles has a production cross section large enough to be detectable with
the energy and luminosity of Run 1, both via its decay to WZ and to Wh, while
the others have suppressed production rates. The model can be tested at the
higher-energy and higher-luminosity run of the LHC even for an overall scale of
the new particles higher than 3 TeV. | hep-ph |
Affleck-Dine dynamics and the dark sector of pangenesis: Pangenesis is the mechanism for jointly producing the visible and dark matter
asymmetries via Affleck-Dine dynamics in a baryon-symmetric universe. The
baryon-symmetric feature means that the dark asymmetry cancels the visible
baryon asymmetry and thus enforces a tight relationship between the visible and
dark matter number densities. The purpose of this paper is to analyse the
general dynamics of this scenario in more detail and to construct specific
models. After reviewing the simple symmetry structure that underpins all
baryon-symmetric models, we turn to a detailed analysis of the required
Affleck-Dine dynamics. Both gravity-mediated and gauge-mediated supersymmetry
breaking are considered, with the messenger scale left arbitrary in the latter,
and the viable regions of parameter space are determined. In the gauge-mediated
case where gravitinos are light and stable, the regime where they constitute a
small fraction of the dark matter density is identified. We discuss the
formation of Q-balls, and delineate various regimes in the parameter space of
the Affleck-Dine potential with respect to their stability or lifetime and
their decay modes. We outline the regions in which Q-ball formation and decay
is consistent with successful pangenesis. Examples of viable dark sectors are
presented, and constraints are derived from big bang nucleosynthesis, large
scale structure formation and the Bullet cluster. Collider signatures and
implications for direct dark matter detection experiments are briefly
discussed. The following would constitute evidence for pangenesis:
supersymmetry, GeV-scale dark matter mass(es) and a Z' boson with a significant
invisible width into the dark sector. | hep-ph |
A New Hypothesis on the Origin of the Three Generations: We suggest that the Standard Model may undergo a supercritical transition
near the Landau scale, where the U(1) gauge boson couples to the left and right
handed states of any given fermion with different charges. This scenario
naturally gives rise to three generations of fermion, corresponding to the
three critical scales for the right-right, right-left and left-left fermion
interactions going supercritical, as well as CP violation in the quark sector. | hep-ph |
Lepton flavor violation beyond the MSSM: Most extensions of the Standard Model lepton sector predict large lepton
flavor violating rates. Given the promising experimental perspectives for
lepton flavor violation in the next few years, this generic expectation might
offer a powerful indirect probe to look for new physics. In this review we will
cover several aspects of lepton flavor violation in supersymmetric models
beyond the Minimal Supersymmetric Standard Model. In particular, we will
concentrate on three different scenarios: high-scale and low-scale seesaw
models as well as models with R-parity violation. We will see that in some
cases the LFV phenomenology can have characteristic features for specific
scenarios, implying that dedicated studies must be performed in order to
correctly understand the phenomenology in non-minimal supersymmetric models. | hep-ph |
Domain walls in the Two-Higgs-Doublet Model and their charge and
CP-violating interactions with Standard Model fermions: Discrete symmetries play an important role in several extensions of the
Standard Model (SM) of particle physics. For instance, in order to avoid flavor
changing neutral currents, a discrete $Z_2$ symmetry is imposed on the
Two-Higgs-Doublet Model (2HDM). This can lead to the formation of domain walls
(DW) as the $Z_2$ symmetry gets spontaneously broken during electroweak
symmetry breaking in the early universe and domain walls form between regions
whose vacua are related by the discrete symmetry. Due to this simultaneous
spontaneous breaking of both the discrete symmetry and the electroweak
symmetry, the vacuum manifold consists of two disconnected 3-spheres. Such a
non-trivial disconnected vacuum manifold leads to several choices for the vacua
at two adjacent regions, in contrast to models where only the discrete symmetry
gets spontaneously broken and the vacuum manifold consists of several
disconnected points. Due to this, we end up with several classes of DW
solutions having different properties localized inside the wall, such as charge
and/or CP violating vacua. We discuss the properties of these different classes
of DW solutions as well as the interaction of SM fermions with such topological
defects leading to different exotic phenomena such as, for example, the top
quark being transmitted or reflected off the wall as a bottom quark. | hep-ph |
A new approach for calculating the Nambu-Gorkov propagator in color
superconductivity theory: In this article, we propose a new approach to calculate the Nambu-Gorkov
propagator intuitively with some linear algebra techniques in presence of the
scalar diquark condensates. With the help of energy projective operators, we
can obtain relatively simple expressions for the quark propagators, which
greatly facilitate the calculations in solving the Schwinger-Dyson equation to
obtain the gap parameters. | hep-ph |
More on Parametrization Relevant to Describe Violation of CP, T and CPT
Symmetries in the $K^0-\bar{K^0}$ System: To study violation of CP, T and/or CPT symmetries in the $K^0-\bar{K^0}$
systems, one has to parametrize the relevant mixing parameters and decay
amplitudes in such a way that each parameter represents violation of these
symmetries in a well-defined way. Parametrization is of course not unique and
is always subject to phase ambiguities. We discuss these problems with freedom
associated with rephasing of final (or intermediate) as well as initial states
taken into account. We present a fully rephasing-invariant parametrization and
a particular rephasing-dependent parametrization, and give a couple of comments
related to these and other possible parametrizations. | hep-ph |
Leading Order Calculation of Electric Conductivity in Hot Quantum
Electrodynamics from Diagrammatic Methods: Using diagrammatic methods, we show how the Ward identity can be used to
constrain the ladder kernel in transport coefficient calculations. More
specifically, we use the Ward identity to determine the necessary diagrams that
must be resummed using an integral equation. One of our main results is an
equation relating the kernel of the integral equation with functional
derivatives of the full self-energy; it is similar to what is obtained with 2PI
effective action methods. However, since we use the Ward identity as our
starting point, gauge invariance is preserved. Using power counting arguments,
we also show which self-energies must be included in the resummation at leading
order, including 2 to 2 scatterings and 1 to 2 collinear scatterings with the
LPM effect. We show that our quantum field theory result is equivalent to the
one of Arnold, Moore and Yaffe obtained using effective kinetic theory. In this
paper we restrict our discussion to electrical conductivity in hot QED, but our
method can in principle be generalized to other transport coefficients and
other theories. | hep-ph |
Gluon correlations from a Glasma flux-tube model compared to measured
hadron correlations on transverse momentum $\bf (p_t,p_t)$ and angular
differences $\bf (η_Δ,φ_Δ)$: A Glasma flux-tube model has been proposed to explain strong elongation on
pseudorapidity $\eta$ of the same-side 2D peak in minimum-bias angular
correlations from $\sqrt{s_{NN}} = 200$ GeV \auau collisions. The same-side
peak or "soft ridge" is said to arise from coupling of flux tubes to radial
flow. Gluons radiated transversely from flux tubes are boosted by radial flow
to form a narrow structure or ridge on azimuth. In this study we test the
conjecture by comparing predictions for particle production, spectra and
correlations from the Glasma model and conventional fragmentation processes
with measurements. We conclude that the Glasma model is contradicted by
measured hadron yields, spectra and correlations, whereas a two-component model
of hadron production, including minimum-bias parton fragmentation, provides a
quantitative description of most data, although $\eta$ elongation remains
unexplained. | hep-ph |
Unitary and Analytic Models in Particle Physics Phenomenology: After two decades of a development of the unitary and analytic models of the
electromagnetic structure of hadrons and nuclei their main principles are
briefly formulated, then a general scheme of their applications to the
electromagnetic, weak and strong interaction processes are traced out and
finally, some results of their successful applications are reviewed. | hep-ph |
Thoughts about the utility of perturbative QCD in the cores of neutron
stars: In this contribution, I discuss the utility that perturbative QCD offers in
studying the matter in the cores of neutron stars. I discuss the reasons why
perturbative QCD can constrain the equation of state at densities far below the
densities where we can perform controlled calculations. I discuss how
perturbative QCD can inform nuclear modelling of neutron stars and how it
influences equation-of-state inference. And finally, I discuss the implications
to the QCD phase diagram and argue that interesting features in the equation of
state revealed by the QCD input may be used to argue for the existence of
quark-matter cores in most massive neutron stars. | hep-ph |
Dark matter astrometry at underground detectors with multiscatter events: We show that current and imminent underground detectors are capable of
precision astrometry of dark matter. First we show that galactic dark matter
velocity distributions can be obtained from reconstructed tracks of dark matter
scattering on multiple nuclei during transit; using the liquid scintillator
neutrino detector SNO+ as an example, we find that the dark matter velocity
vector can be reconstructed event-by-event with such a small uncertainty, that
the precision of dark matter astrometry will be limited mainly by statistics.
We then determine the number of dark matter events required to determine the
dispersion speed, escape speed, and velocity anisotropies of the local dark
matter halo, and also find that with as few as $\mathcal{O}(10)$ events, dark
matter signals may be discriminated from potential backgrounds arising as
power-law distributions. Finally, we discuss the prospects of dark matter
astrometry at other liquid scintillator detectors, dark matter experiments, and
the recently proposed MATHUSLA detector. | hep-ph |
Improving the J/psi Production Baseline at RHIC and the LHC: We assess the theoretical uncertainties on the inclusive J/psi production
cross section in the Color Evaporation Model (CEM) using values for the charm
quark mass, renormalization and factorization scales obtained from a fit to the
charm production data. We use our new results to provide improved baseline
comparison calculations at RHIC and the LHC. We also study cold matter effects
on J/psi production at leading relative to next-to-leading order in the CEM
within this approach. | hep-ph |
What Can We Learn About Leptoquarks At LEP200?: We investigate the discovery potential for first generation leptoquarks at
the LEP200 $e^+e^-$ collider. We consider direct leptoquark searches using
single leptoquark production via resolved photon contributions which offers a
much higher kinematic limit than the more commonly considered leptoquark pair
production process. Depending on the coupling strength of the leptoquark,
search limits can be obtained to within a few GeV of $\sqrt{s}$. We also
consider LQ limits that can be obtained from t-channel interferences effects in
$e^+e^- \to hadrons$. | hep-ph |
The predictions of the charm structure function exponents behaviour at
low x in deep inelastic scattering: We use the hard (Lipatov) pomeron for the low-x gluon distribution and
provide a compact formula for the ratio $R^{c} =F_{L}^{c}/F_{2}^{c}$ that is
useful to extract the charm structure function from the reduced charm
cross-section, in particular at DESY HERA. Our results show that this ratio is
independent of x and independent of the DGLAP evolution of the gluon PDF. As a
result, we show that the charm structure function and the reduced charm
cross-section exponents do not have the same behaviour at very low x. This
difference is independent of the input gluon distribution functions and
predicts the non-linear effects and some evidence for shadowing and
antishadowing at HERA and RHIC. | hep-ph |
Quark-Lepton Flavor Democracy and the Non-Existence of the Fourth
Generation: In the Standard Model with two Higgs doublets (type II), which has a
consistent trend to a flavor gauge theory and its related flavor democracy in
the quark and the leptonic sectors (unlike the minimal Standard Model) when the
energy of the probes increases, we impose the mixed quark-lepton flavor
democracy at high ``transition'' energy and assume the usual see-saw mechanism,
and consequently find out that the existence of the fourth generation of
fermions in this framework is practically ruled out. | hep-ph |
Neutralino Dark Matter and Other LHC Predictions from Quasi Yukawa
Unification: We explore the dark matter and LHC implications of t-b-tau quasi Yukawa
unification in the framework of supersymmetric models based on the gauge
symmetry G=SU(4)_{c}\times SU(2)_{L}\times SU(2)_{R}. The deviation from exact
Yukawa unification is quantified by a dimensionless parameter C (|C| <~ 0.2),
such that the Yukawa couplings at M_GUT are related by y_t:y_b:y_tau=|1+C| :
|1-C| : |1+3C|. In contrast to earlier studies which focused on universal
gaugino masses, we consider non-universal gaugino masses at M_GUT that are
compatible with the gauge symmetry G. We perform two independent scans of the
fundamental parameter space, one of which employs ISAJET, while the other uses
SoftSusy interfaced with SuperIso. These scans reveal qualitatively similar
allowed regions in the parameter space, and yield a variety of neutralino dark
matter scenarios consistent with the observations. These include stau and
chargino coannihilation scenarios, the A-resonance scenario, as well as
Higgsino dark matter solution which is more readily probed by direct detection
searches. The gluino mass is found to be <~ 4.2 TeV, the stop mass is >~ 2 TeV,
while the first two family squarks and sleptons are of order 4-5 TeV and 3 TeV
respectively. | hep-ph |
$D_s$ Lifetime, $m_b$, $m_c$ and $|V_{cb}|$ in the Heavy Quark Expansion: We present some straightforward applications of the QCD heavy quark
expansion, stated in previous papers [1-3], to the inclusive widths of heavy
flavour hadrons. We address the question of the $D_s$ lifetime and argue that
-- barring Weak Annihilation (WA) -- $\tau (D_s)$ is expected to exceed $\tau
(D^0)$ by several percent; on the other hand WA could provide a difference of
up to $10\div20\%$ of {\it any} sign. We extract $m_c$, $m_b$ and $|V_{cb}|$
from $\Gamma\ind{SL}(D^+)$ and $\Gamma\ind{SL}(B)$. The values of the quark
masses are somewhat higher, but compatible with estimates from QCD sum rules;
we obtain $|V_{cb}|\simeq 0.043$ for $\tau (B)=1.4$ psec and
$BR_{SL}(B)=10.5$\% . We discuss the associated uncertainties in the $1/m_Q$
expansion as well as some consequences for other electroweak decays. | hep-ph |
On Supersymmetries: After reviewing electroweak (EW) scale supersymmetry (susy) and split susy,
as well as their implications in very high energy cosmic rays, I present a high
scale susy model for fermion masses. An O(0.1) nu_e-nu_{tau} mixing is
expected. | hep-ph |
On the Spectrum of Lattice Massive SU(2) Yang-Mills: On the basis of extended simulations we provide some results concerning the
spectrum of Massive SU(2) Yang-Mills on the lattice. We study the "time"
correlator of local gauge invariant operators integrated over the remaining
three dimensions. The energy gaps are measured in the isospin I=0,1 and
internal spin J=0,1 channels. No correlation is found in the I=1,J=0 channel.
In the I=1, J=1 channel and far from the critical mass value $m_c$ the energy
gap roughly follows the bare value $m$ (vector mesons). In approaching the
critical value $m_c$ at $\beta$ fixed, there is a bifurcation of the energy
gap: one branch follows the value $m$, while the new is much larger and it
shows a more and more dominant weight. This phenomenon might be the sign of two
important features: the long range correlation near the fixed point at $\beta
\to \infty$ implied by the low energy gap and the screening (or confining)
mechanisms across the $m=m_c$ associated to the larger gap. The I=0, J=0,1 gaps
are of the same order of magnitude, typically larger than the I=1, J=1 gap (for
$m>>m_c$). For $m\sim m_c$ both I=0 gaps have a dramatic drop with minima near
the value $m$. This behavior might correspond to the formation of I=0 bound
states both in the J=0 and J=1 channels. | hep-ph |
Charmless $B_{u,d,s}\to VT$ decays in perturbative QCD approach: Motivated by the experimental data, we study charmless $B_{u,d,s}\to VT$ ($V$
and $T$ denote light vector and tensor mesons respectively) decays in the
perturbative QCD approach. The predictions of branching ratios, polarization
fractions and direct CP violations are given in detail. Specifically, within
this approach we have calculated the polarization fractions and the branching
ratios of $B\to \phi(K_2^{*-}, \bar K_2^{*0})$ which agree well with the
observed experimental data, however the branching ratios of $B\to
\omega(K_2^{*-}, \bar K_2^{*0})$ are hard to be explained, where the
polarization fractions are well accommodated. The tree dominated channels with
a vector meson emitted have longitudinal polarization fraction of 90%, while
the penguin dominating ones have subtle polarization fractions. Fortunately,
most branching ratios of $B_{u,d}$ decays are of the order $10^{-6}$, which
would be straight forward for experimental observations. For the $B_s$ decays
the branching ratios can reach the order of $10^{-6}$ in tree dominated decays,
while in penguin dominated decays those are of order of $10^{-7}$ which require
more experimental data to be observed. | hep-ph |
Higgs production in hadron collisions: soft and virtual QCD corrections
at NNLO: We consider QCD corrections to Higgs boson production through gluon-gluon
fusion in hadron collisions. Using the recently evaluated two-loop amplitude
for this process and the corresponding factorization formulae for soft-gluon
bremsstrahlung at O(alpha_s^2), we compute the soft and virtual contributions
to the NNLO cross section. We also discuss soft-gluon resummation at
next-to-next-to-leading logarithmic accuracy. Numerical results for Higgs boson
production at the LHC are presented. | hep-ph |
Primordial magnetic fields, anomalous isocurvature fluctuations and Big
Bang nucleosynthesis: We show that the presence of primordial stochastic (hypercharge) magnetic
fields before the electroweak (EW) phase transition induces isocurvature
fluctuations (baryon number inhomogeneities). Depending on the details of the
magnetic field spectrum and on the particle physics parameters (such as the
strength of the EW phase transition and electron Yukawa couplings) these
fluctuations may survive until the Big Bang nucleosynthesis (BBN). Their
lenghtscale may exceed the neutron diffusion length at that time, while their
magnitude can be so large that sizable antimatter domains are present. This
provides the possibility of a new type of initial conditions for
non-homogeneous BBN or, from a more conservative point of view, stringent
bounds on primordial magnetic fields. | hep-ph |
Excess Cross-Sections at the Electroweak Scale in the Sextet Quark
``Standard Model'': If dynamical electroweak symmetry breaking is due to a flavor doublet of
color sextet quarks, enhanced electroweak scale QCD instanton interactions may
produce a large top mass, raise the $\eta_6$ axion mass, and also explain the
excesses in the DIS cross-section at HERA and jet cross-sections at the
Tevatron. | hep-ph |
Determination of QCD condensates from tau-decay data: We have used the latest data from the ALEPH Collaboration to extract values
for QCD condensates up to dimension d=12 in the V-A channel and up to dimension
d=8 in the V, A and V+A channels. Performing 2- and 3-parameter fits, we obtain
new results for the correlations of condensates. The results are consistent
among themselves and agree with most of the previous results found in the
literature. | hep-ph |
Initial fields and instability in the classical model of the heavy-ion
collision: Color Glass Condensate (CGC) provides a classical description of dense gluon
matter at high energies. Using the McLerran-Venugopalan (MV) model we calculate
the initial energy density \epsilon(\tau) in the early stage of the
relativistic nucleus-nucleus collision. Our analytical formula reproduces the
quantitative results from lattice discretized simulations and leads to an
estimate \epsilon(\tau=0.1fm)=40-50GeV/fm^3 in the Au-Au collision at RHIC
energy. We then formulate instability with respect to soft fluctuations that
violate boost invariance inherent to hard CGC backgrounds. We find unstable
modes arising as a result of ensemble average over the initial CGC fields. | hep-ph |
Chiral asymmetry and axial anomaly in magnetized relativistic matter: The induced axial current and the chiral anomaly are studied in the normal
phase of magnetized relativistic matter. A special attention is paid to the
role of the chiral shift parameter Delta, leading to a relative shift of the
longitudinal momenta in the dispersion relations of opposite chirality
fermions. In the Nambu-Jona-Lasinio model, it is shown directly from the form
of the gap equation that Delta necessarily exists in the normal phase in a
magnetic field. By making use of the gauge invariant point-splitting
regularization, we then show that the presence of Delta essentially modifies
the form of the axial current, but does not affect the conventional axial
anomaly relation. By recalculating the axial current with the proper-time
regularization, we conclude that the result is robust with respect to a
specific regularization scheme used. | hep-ph |
Jet quenching phenomenology from soft-collinear effective theory with
Glauber gluons: We present the first application of a recently-developed effective theory of
jet propagation in matter SCETG to inclusive hadron suppression in
nucleus-nucleus collisions at the LHC. SCETG-based splitting kernels allow us
to go beyond the traditional energy loss approximation and unify the treatment
of vacuum and medium-induced parton showers. In the soft gluon emission limit,
we establish a simple analytic relation between the QCD evolution and energy
loss approaches to jet quenching. We quantify the uncertainties associated with
the implementation of the in-medim modification of hadron production cross
sections and show that the coupling between the jet and the medium can be
constrained with better than 10% accuracy. | hep-ph |
The Effect of Weak Interactions on the Ultra-Relativistic Bose-Einstein
Condensation Temperature: We calculate the ultra-relativistic Bose-Einstein condensation temperature of
a complex scalar field with weak lambda Phi^4 interaction. We show that at high
temperature and finite density we can use dimensional reduction to produce an
effective three-dimensional theory which then requires non-perturbative
analysis. For simplicity and ease of implementation we illustrate this process
with the linear delta expansion. | hep-ph |
Has HERA reached a new QCD regime?: These notes are a summary of our efforts to answer the question in the title.
Our answer is in the affirmative as: (i) HERA data indicate a large value of
the gluon structure function; (ii) no contradictions with the asymptotic
predictions of high density QCD have been observed; and (iii) the numerical
estimates of our model give a natural description of the size of deviation from
the routine DGLAP explanation. We discuss the alternative approaches and
possible new experiments. | hep-ph |
Electroweak and supersymmetric two-loop corrections to lepton anomalous
magnetic and electric dipole moments: Using the effective Lagrangian method, we analyze the electroweak corrections
to the anomalous dipole moments of lepton from some special two-loop diagrams
where a closed neutralino/chargino loop is inserted into relevant two Higgs
doublet one-loop diagrams in the minimal supersymmetric extension of the
standard model with CP violation. Considering the translational invariance of
loop momenta and the electromagnetic gauge invariance, we get all dimension 6
operators and derive their coefficients. After applying equations of motion to
the external leptons, we obtain the anomalous dipole moments of lepton. The
numerical results imply that there is parameter space where the contributions
to the muon anomalous dipole moments from this sector may be significant. | hep-ph |
Nonequilibrium Chiral Dynamics and Effective Lagrangians: We review our recent work on Chiral Lagrangians out of thermal equilibrium,
which are introduced to analyse the pion gas formed after a Relativistic Heavy
Ion Collision. Chiral Perturbation Theory is extended by letting $\fpi$ be time
dependent and allows to describe explosive production of pions in parametric
resonance. This mechanism could be relevant if hadronization occurs at the
chiral phase transition. | hep-ph |
Comment on the Theta+ width and mass: We discuss the relatively low mass and narrow width prediction for the exotic
baryon Theta+, and comment on recent statements by R.L. Jaffe on the subject.
We reaffirm that a narrow width of 3.6-11.2 MeV follows from the equations of
our 1997 paper. | hep-ph |
Positivity issues for the pinch-technique gluon propagator and their
resolution: Although gauge-boson propagators in asymptotically-free gauge theories
satisfy a dispersion relation, they do not satisfy the K\"allen-Lehmann (KL)
representation because the spectral function changes sign. We argue that this
is a simple consequence of asymptotic freedom. On the basis of the QED-like
Ward identities of the pinch technique (PT) we claim that the product of the
coupling $g^2$ and the scalar part $\hat{d}(q^2)$ of the PT propagator, which
is both gauge invariant and renormalization-group invariant, can be factored
into the product of the running charge $\bar{g}^2(q^2)$ and a term
$\hat{H}(q^2)$ both of which satisfy the KL representation although their
product does not. We show that this behavior is consistent with some simple
analytic models that mimic the gauge-invariant PT Schwinger-Dyson equations
(SDE) provided that the dynamic gauge boson mass is sufficiently large. The PT
SDEs do not depend directly on the PT propagator through $\hat{D}$ but only
through $\hat{H}$. | hep-ph |
Discrete Symmetry, Neutrino Magnetic Moment and the 17 Kev Neutrino: The problem of generating large transition magnetic moments for nearly
massless neutrinos in a truly three--generation case is discussed. A model to
achieve the same by exploiting an octahedral symmetry is presented. The scheme
also accomodates a radiatively generated mass of $17\:keV$ for a pseudo--Dirac
neutrino that decays rapidly through the Majoron channel. | hep-ph |
Hadronic structure on the light-front VI. Generalized parton
distributions of unpolarized hadrons: We discuss the generalized parton distributions (GPDs) for unpolarized
hadrons, as a continuation of our recent work on hadronic structure on the
light front. We analyze the unpolarized GPDs for the light nucleon and delta,
as well as generic mesons, using the lowest Fock states. We use these GPDs to
reconstruct the charge and gravitational form factors, and discuss their
relative sizes. The results are also compared to reported QCD lattice results. | hep-ph |
Composite Higgs to two Photons and Gluons: We introduce a simple framework to estimate the composite Higgs boson
coupling to two-photon in Technicolor extensions of the standard model. The
same framework allows us to predict the composite Higgs to two-gluon process.
We compare the decay rates with the standard model ones and show that the
corrections are typically of order one. We suggest, therefore, that the
two-photon decay process can be efficiently used to disentangle a light
composite Higgs from the standard model one. We also show that the Tevatron
results for the gluon-gluon fusion production of the Higgs either exclude the
techniquarks to carry color charges to the 95% confidence level, if the
composite Higgs is light, or that the latter must be heavier than around 200
GeV. | hep-ph |
The Gerasimov-Drell-Hearn sum rule and the infinite-momentum limit: We study the current-algebra approach to the Gerasimov-Drell-Hearn sum rule,
paying particular attention to the infinite-momentum limit. Employing the
order-alpha^2 Weinberg-Salam model of weak interactions as a testing ground, we
find that the legitimacy of the infinite-momentum limit is intimately connected
with the validity of the naive equal-times algebra of electric charge
densities. Our results considerably reduce the reliability of a recently
proposed modification of the Gerasimov-Drell-Hearn sum rule, originating from
an anomalous charge-density algebra. | hep-ph |
Current correlators to all orders in the quark masses: The contributions to the coefficient functions of the quark and the mixed
quark-gluon condensate to mesonic correlators are calculated for the first time
to all orders in the quark masses, and to lowest order in the strong coupling
constant. Existing results on the coefficient functions of the unit operator
and the gluon condensate are reviewed. The proper factorization of short- and
long-distance contributions in the operator product expansion is discussed in
detail. It is found that to accomplish this task rigorously the operator
product expansion has to be performed in terms of non-normal-ordered
condensates. The resulting coefficient functions are improved with the help of
the renormalization group. The scale invariant combination of dimension 5
operators, including mixing with the mass operator, which is needed for the
renormalization group improvement, is calculated in the leading order. | hep-ph |
Cabibbo-favored $Λ^+_c\toΛa_{0}(980)^+$ decay in the final
state interaction: The anti-triplet charmed baryon decays with the light scalar mesons are
rarely measured, whereas the recent observation of the Cabibbo-favored
$\Lambda_c^+\to \Lambda\eta\pi^+$ decay hints a possible $\Lambda_c^+\to\Lambda
a_0(980)^+,a_0(980)^+\to \eta\pi^+$ process. We hence study the
$\Lambda_c^+\to\Lambda a_0(980)^+$ decay. Particularly, it is found that the
final state interaction can give a significant contribution, where
$\Sigma^{+}(1385)$ and $\eta$ in $\Lambda_c^+\to \Sigma^{+}(1385)\eta$ by
exchanging a charged pion are transformed as $\Lambda$ and $a_0(980)^+$,
respectively. Accordingly, we predict ${\cal B}(\Lambda_c^+\to\Lambda
a_0(980)^+)=(1.7^{+2.8}_{-1.0}\pm 0.3)\times 10^{-3}$, accessible to the
BESIII, BELLEII and LHCb experiments. | hep-ph |
The static potential in QCD to two loops: We evaluate the static QCD potential to two--loop order. Compared to a
previous calculation a sizable reduction of the two--loop coefficient $a_2$ is
found. | hep-ph |
Update of the Hagedorn mass spectrum: We present an update of the Hagedorn hypothesis of the exponential growth of
the number of hadronic resonances with mass. We use the newest available
experimental data for the non-strange mesons and baryons, as well as fill in
some missing states according to the observation that the high-lying states
form chiral multiplets. The results show, especially for the case of the
mesons, that the Hagedorn growth continues with the increasing mass, with the
new states lining up along the exponential growth. | hep-ph |
Limits on Cosmological Variation of Strong Interaction and Quark Masses
from Big Bang Nucleosynthesis, Cosmic, Laboratory and Oklo Data: Recent data on cosmological variation of the electromagnetic fine structure
constant from distant quasar (QSO) absorption spectra have inspired a more
general discussion of possible variation of other constants. We discuss
variation of strong scale and quark masses. We derive the limits on their
relative change from (i) primordial Big-Bang Nucleosynthesis (BBN); (ii)
Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv)
laboratory measurements of hyperfine intervals. | hep-ph |
Higgs Physics: These lectures review the background to Higgs physics, its current status
following the discovery of a/the Higgs boson at the LHC, models of Higgs
physics beyond the Standard Model and prospects for Higgs studies in future
runs of the LHC and at possible future colliders. | hep-ph |
Geometry of the neutrino mixing space: We study a geometric structure of a physical region of neutrino mixing
matrices as part of the unit ball of the spectral norm. Each matrix from the
geometric region is a convex combination of unitary PMNS matrices. The disjoint
subsets corresponding to a different minimal number of additional neutrinos are
described as relative interiors of faces of the unit ball. We determined the
Carath\'eodory's number showing that, at most, four unitary matrices of
dimension three are necessary to represent any matrix from the neutrino
geometric region. For matrices which correspond to scenarios with one and two
additional neutrino states, the Carath\'eodory's number is two and three,
respectively. Further, we discuss the volume associated with different
mathematical structures, particularly with unitary and orthogonal groups, and
the unit ball of the spectral norm. We compare the obtained volumes to the
volume of the region of physically admissible mixing matrices for both the
CP-conserving and CP-violating cases in the present scenario with three
neutrino families and scenarios with the neutrino mixing matrix of dimension
higher than three. | hep-ph |
Probing New Physics With b Decays: I discuss how b decays can be used to unravel new physics beyond the Standard
Model. Decays second order in the weak interaction involving loops and CP
violation are emphasized. This information is complementary to that obtainable
with higher energy machines. | hep-ph |
A screening mechanism for extra W and Z gauge bosons: We generalize a previous construction of a fermiophobic model to the case of
more than one extra $W$ and $Z$ gauge bosons. We focus in particular on the
existence of screening configurations and their implication on the gauge boson
mass spectrum. One of these configurations allows for the existence of a set of
relatively light new gauge bosons, without violation of the quite restrictive
bounds coming from the $\rho_{\rm NC}$ parameter. The links with Bess and
degenerate Bess models are also discussed. Also the signal given here by this
more traditional gauge extension of the SM could help to disentangle it from
the towers of Kaluza-Klein states over $W$ and $Z$ gauge bosons in extra
dimensions. | hep-ph |
A study of the resonances $K_{0}^{*}(800)$ and $K_{0}^{*}(1430)$: We study the scalar kaonic states $K_{0}^{\ast}(800)$ and
$K_{0}^{\ast}(1430)$ by using a relativistic QFT Lagrangian in which only a
single kaonic field corresponding to the well-established scalar state
$K_{0}^{\ast}(1430)$ is considered and in which both derivative and
non-derivative interaction terms are taken into account. Even if the scalar
spectral function shows a unique peak close to $1.4$ GeV, we find two poles in
the complex plane: $1.413\pm0.002-i(0.127\pm0.003)$ GeV, which is related to
the seed quark-antiquark state $K_{0}^{\ast}(1430),$ and
$0.746\pm0.019-i(262\pm0.014)$ GeV, which is an additional companion pole
related to $K_{0}^{\ast}(800)$. As a further investigation for increasing
$N_{c}$ confirms, $K_{0}^{\ast}(800)$ emerges as a dynamically generated
four-quark object as a consequence of pion-kaon loops. | hep-ph |
A note on Higgs decays into $Z$ boson and $J/Ψ(Υ)$: Rare decays $h\to Z V$ with $V$ denoting the narrow $c\bar{c}$ or $b\bar{b}$
resonances, such as $J/\Psi$ or $\Upsilon$ states, have been analyzed. Within
the standard model, these channels may proceed through the tree-level
transition $h\to ZZ^*$ with the virtual $Z^*\to V$, and also loop-induced
process $h\to Z\gamma^*$, followed by $\gamma^*\to V$. Our analysis shows that,
for the bottomonium final states, the decay rate of $h\to Z \Upsilon$ from the
loop-induced process is small and the former transition gives the dominant
contribution; while, for the charmonium final states, $\Gamma(h\to Z J/\Psi)$
and $\Gamma(h\to Z\Psi(2S))$ induced by $h\to Z\gamma^* \to Z V$ could be
comparable to the contribution given by the tree-level $h\to ZZ^*\to Z V$
transition. | hep-ph |
Axionic Mirage Mediation: In this talk, we propose a model of mirage mediation, in which Peccei-Quinn
symmetry is incorporated. In this \textit{axionic mirage mediation}, it is
shown that the Peccei-Quinn symmetry breaking scale is dynamically determined
around $10^{10}$ GeV to $10^{12}$ GeV due to the supersymmetry breaking
effects. The problems in the original mirage mediation such as the
$\mu$-problem and the moduli problem can be solved simultaneouly. Furthermore,
in our model the axino, which is the superpartner of the axion, is the lightest
sparticle. | hep-ph |
Deuteron Magnetic Quadrupole Moment From Chiral Effective Field Theory: We calculate the magnetic quadrupole moment (MQM) of the deuteron at leading
order in the systematic expansion provided by chiral effective field theory. We
take into account parity and time-reversal violation which, at the quark-gluon
level, results from the QCD vacuum angle and dimension-six operators that
originate from physics beyond the Standard Model. We show that the deuteron MQM
can be expressed in terms of five low-energy constants that appear in the
parity- and time-reversal-violating nuclear potential and electromagnetic
current, four of which also contribute to the electric dipole moments of light
nuclei. We conclude that the deuteron MQM has an enhanced sensitivity to the
QCD vacuum angle and that its measurement would be complementary to the
proposed measurements of light-nuclear EDMs. | hep-ph |
Predicting the Pion and Eta Masses as Quantum Corrections without Quark
Masses: This paper is removed because it used an approximation, which alters some of
the conclusions. Another paper will be written in the near future. | hep-ph |
Probing the Dark Matter of Three-loop Radiative Neutrino Mass Generation
Model with the Cherenkov Telescope Array: We investigate the prospect of detecting the Dark Matter (DM) candidate in
the three-loop radiative neutrino mass generation model extended with large
electroweak multiplets of the Standard Model (SM) gauge group, at the future
imaging atmospheric Cherenkov telescope known as the Cherenkov Telescope Array
(CTA). We find that the addition of such large electroweak multiplets leads to
a sizable Sommerfeld enhanced annihilation of the DM with $O(\text{TeV})$ mass,
into the SM gauge bosons which results in continuum and line-like spectra of
very high energy (VHE) gamma-rays, and therefore becomes observable for the
CTA. We determine the viable models by setting the upper limit on the
$SU(2)_{L}$ isospin of the multiplets from the partial-wave unitarity
constraints and the appearance of low-scale Landau pole in the gauge coupling.
Afterwards, by considering the continuum VHE gamma-rays produced from the DM
annihilation at the Galactic center, we probe the parameter space of the model
using the sensitivity reach of the CTA. | hep-ph |
Probing initial geometrical anisotropy and final azimuthal anisotropy in
heavy-ion collisions at Large Hadron Collider energies through event-shape
engineering: Anisotropic flow is accredited to have effects from the initial state
geometry and fluctuations in the nuclear overlap region. The elliptic flow
($v_2$) and triangular flow ($v_3$) coefficients of the final state particles
are expected to have influenced by eccentricity ($\varepsilon_2$) and
triangularity ($\varepsilon_3$) of the participants, respectively. In this
work, we study $v_2$, $v_3$, $\varepsilon_2$, $\varepsilon_3$ and the
correlations among them with respect to event topology in the framework of a
multi-phase transport model (AMPT). We use transverse spherocity and reduced
flow vector as event shape classifiers in this study. Transverse spherocity has
the unique ability to separate events based on geometrical shapes, i.e., jetty
and isotropic, which pertain to pQCD and non-pQCD domains of particle
production in high-energy physics, respectively. We use the two-particle
correlation method to study different anisotropic flow coefficients. We
confront transverse spherocity with a more widely used event shape classifier
-- reduced flow vector ($q_n$) and they are found to have significant
(anti-)correlations among them. We observe significant spherocity dependence on
$v_2$, $v_3$ and $\varepsilon_2$. This work also addresses transverse momentum
dependent crossing points between $v_2$ and $v_3$, which varies for different
centrality and spherocity percentiles. | hep-ph |
Hadron-hadron collision mode in ReneSANCe-v1.3.0: We report an implementation of the hadron-hadron ($pp$ and $p\bar{p}$)
collision mode to the Monte Carlo event generator ReneSANCe - the code that was
previously developed for $e^+e^-$ collisions. The described extension of
ReneSANCe currently contains neutral and charged current Drell-Yan prosesses
$pp[p\bar{p}] \to ZX \to \ell^+\ell^- X$, $pp[p\bar{p}] \to W^+X \to
\ell^+\nu_\ell X$ and $pp[p\bar{p}] \to W^-X \to \ell^-\bar{\nu}_\ell X$. We
take into account complete one-loop electroweak (EW) and one-loop QCD
corrections to these processes. The calculation is based on the SANC (Support
for Analytic and Numeric Calculations for experiments at colliders) modules.
The generator is constructed in such a way that new processes can be easily
added. The paper contains a theoretical description of the SANC approach,
numerical validations and a manual. | hep-ph |
Dissipative Effects on Reheating after Inflation: The inflaton must convert its energy into radiation after inflation, which,
in a conventional scenario, is caused by the perturbative inflaton decay. This
reheating process would be much more complicated in some cases: the decay
products obtain masses from an oscillating inflaton and thermal environment,
and hence the conventional reheating scenario can be modified. We study in
detail processes of particle production from the inflaton, their subsequent
thermalization and evolution of inflaton/plasma system by taking dissipation of
the inflaton in a hot plasma into account. It is shown that the reheating
temperature is significantly affected by these effects. | hep-ph |
The connection between the DRED and NSVZ renormalisation schemes: We explore the relationship between the DRED and NSVZ schemes. Using certain
exact results for the soft scalar mass $\beta$-function, we derive the
transformation of $\alpha^{\DRED}$ to $\alpha^{\NSVZ}$ through terms of order
$\alpha^4$. We thus incidentally determine $\beta_{\alpha}^{\DRED}$ through
four loops, and we compare our result to a previous Pad\'e Approximant
prediction. | hep-ph |
Herwig++ 2.2 Release Note: A new release of the Monte Carlo program Herwig++ (version 2.2) is now
available. This version includes a number of improvements including: matrix
elements for the production of an electroweak gauge boson, W and Z, in
association with a jet; several new processes for Higgs production in
association with an electroweak gauge boson; and the matrix element correction
for QCD radiation in Higgs production via gluon fusion. | hep-ph |
Late decaying 2-component dark matter scenario as an explanation of the
AMS-02 positron excess: The long standing anomaly in the positron flux as measured by the PAMELA and
AMS-02 experiments could potentially be explained by dark matter (DM)
annihilations. This scenario typically requires a large "boost factor" to be
consistent with a thermal relic dark matter candidate produced via freeze-out.
However, such an explanation is disfavored by constraints from CMB observations
on energy deposition during the epoch of recombination. We discuss a scenario
called late-decaying two-component dark matter (LD2DM), where the entire DM
consists of two semi-degenerate species. Within this framework, the heavier
species is produced as a thermal relic in the early universe and decays to the
lighter species over cosmological timescales. Consequently, the lighter species
becomes the DM which populates the universe today. We show that annihilation of
the lighter DM species with an enhanced cross-section, produced via such a
non-thermal mechanism, can explain the observed AMS-02 positron flux while
avoiding CMB constraints. The observed DM relic density can be correctly
reproduced as well with simple s-wave annihilation cross-sections. We
demonstrate that the scenario is safe from CMB constraints on late-time energy
depositions during the cosmic "dark ages". Interestingly, structure formation
constraints force us to consider small mass splittings between the two dark
matter species. We explore possible cosmological and particle physics
signatures in a toy model that realizes this scenario. | hep-ph |
Testing collinear factorization and nuclear parton distributions with pA
collisions at the LHC: Global perturbative QCD analyses, based on large data sets from
electron-proton and hadron collider experiments, provide tight constraints on
the parton distribution function (PDF) in the proton. The extension of these
analyses to nuclear parton distributions (nPDF) has attracted much interest in
recent years. nPDFs are needed as benchmarks for the characterization of hot
QCD matter in nucleus-nucleus collisions, and attract further interest since
they may show novel signatures of non- linear density-dependent QCD evolution.
However, it is not known from first principles whether the factorization of
long-range phenomena into process-independent parton distribution, which
underlies global PDF extractions for the proton, extends to nuclear effects. As
a consequence, assessing the reliability of nPDFs for benchmark calculations
goes beyond testing the numerical accuracy of their extraction and requires
phenomenological tests of the factorization assumption. Here we argue that a
proton-nucleus collision program at the LHC would provide a set of measurements
allowing for unprecedented tests of the factorization assumption underlying
global nPDF fits. | hep-ph |
Collisions and collective flavor conversion: Integrating out the fast
dynamics: In dense astrophysical environments, notably core-collapse supernovae and
neutron star mergers, neutrino-neutrino forward scattering can spawn flavor
conversion on very short scales. Scattering with the background medium can
impact collective flavor conversion in various ways, either damping
oscillations or possibly setting off novel collisional flavor instabilities
(CFIs). A key feature in this process is the slowness of collisions compared to
the much faster dynamics of neutrino-neutrino refraction. Assuming spatial
homogeneity, we leverage this hierarchy of scales to simplify the description
accounting only for the slow dynamics driven by collisions. We illustrate our
new approach both in the case of CFIs and in the case of fast instabilities
damped by collisions. In both cases, our strategy provides new equations, the
slow-dynamics equations, that simplify the description of flavor conversion and
allow us to qualitatively understand the final state of the system after the
instability, either collisional or fast, has saturated. | hep-ph |
Effective Theory for Heavy Quarkonia Decays: An effective theory approach to heavy quarkonia decays based on the $1/m_Q$
expansion is introduced. Its application to decays in which the two heavy
quarks annihilate is discussed. | hep-ph |
Inverse Primakoff Scattering for Axionlike Particle Coupling: Axionlike particles (ALPs) can be produced in the Sun, and are considered
viable candidates for the cosmological dark matter (DM). It can decay into two
photons or interact with matter. We identify new inelastic channels of inverse
Primakoff processes due to atomic excitation and ionization. Their cross
sections are derived by incorporating full electromagnetic fields of atomic
charge and current densities, and computed by well-benchmarked atomic many-body
methods. Complementing data from the underground XENONnT and surface TEXONO
experiments are analyzed. Event rates and sensitivity reaches are evaluated
with respect to solar- and DM-ALPs. New parameter space in ALP couplings with
the photons versus ALP masses in (1~eV$-$10~keV) not previously accessible to
laboratory experiments are probed and excluded with solar-ALPs. However, at
regions where DM-ALPs have already decayed, there would be no ALP-flux and
hence no interactions at the detectors in direct search experiments. No physics
constraints can be derived. Future projects would be able to evade the
stability bound and open new observable windows in (100~eV$-$1~MeV) for
DM-ALPs. | hep-ph |
Multi-color QCD at High Energies and Exactly Solvable Lattice Theories: We examine the generalized leading-logarithmic approximation (LLA) equations
for compound states of n-reggeized gluons. It is shown that in multi-color QCD,
when $N_c \rightarrow \infty$, these equations have a sufficient number of
conservation laws to be exactly solvable. Holomorphic factorization of the wave
functions is used to reduce the corresponding quantum mechanical problem to the
solution of the one-dimensional Heisenberg model with the spins being the
generators of the M$\ddot{o}$bius group of conformal transformations. | hep-ph |
Resonances in a sudden chemical freeze-out model: The prediction for $p_T$ spectra of various resonances produced in Pb+Pb
collisions at 2.76 TeV at the LHC in equilibrium and non-equilibrium models is
made. It includes the $\eta$, $\rho$(770), $\Sigma$(1385), $\Lambda$(1520), and
$\Xi$(1530). The apparent differences may allow to distinguish between the
models. | hep-ph |
Rare Z-decay into light pseudoscalar bosons in the simplest little Higgs
model: The simplest little Higgs model predicts a light pseudoscalar boson $\eta$
and opens up some new decay modes for $Z$-boson, such as $Z \to \bar{f} f
\eta$, $Z\to \eta\eta\eta$, $Z\to \eta\gamma$ and $Z\to \eta gg$. We examine
these decay modes in the parameter space allowed by current experiments, and
find that the branching ratios can reach $10^{-7}$ for $Z\to \bar{b}b\eta$,
$10^{-8}$ for $Z\to \bar{\tau}\tau\eta$, and $10^{-8}$ for $Z\to \eta\gamma$,
which should be accessible at the GigaZ option of the ILC. However, the
branching ratios can reach $10^{-12}$ for $Z\to \eta\eta\eta$, and $10^{-11}$
for $Z\to \eta gg$, which are hardly accessible at the GigaZ option. | hep-ph |
NNLO QCD$\oplus$QED corrections to Higgs production in bottom quark
annihilation: We present next-to-next-to leading order (NNLO) quantum electrodynamics (QED)
corrections to the production of the Higgs boson in bottom quark annihilation
at the Large Hadron Collider (LHC) in the five flavor scheme. We have
systematically included the NNLO corrections resulting from the interference of
quantum chromodynamics (QCD) and QED interactions. We have investigated the
infrared (IR) structure of the bottom quark form factor up to two loop level in
QED and in QCD$\times$QED using K+G equation. We find that the IR poles in the
form factor are controlled by the universal cusp, collinear and soft anomalous
dimensions. In addition, we derive the QED as well as QCD$\times$QED
contributions to soft distribution function as well as to the ultraviolet
renormalization constant of the bottom Yukawa coupling up to second order in
strong coupling and fine structure constant. Finally, we report our findings on
the numerical impact of the NNLO results from QED and QCD$\times$QED at the LHC
energies taking into account the dominant NNLO QCD corrections. | hep-ph |
Photoproduction of $a_{2}(1320)$ in a Regge model: In this work, the photoproduction of $a_{2}(1320)$ off a proton target is
investigated within an effective Lagrangian approach and the Regge model. The
theoretical result indicates that the shapes of {the} total and differential
cross sections of the $\gamma p\rightarrow a_{2}^{+}n$ reaction within the
Feynman (isobar) model are much different from that of the Reggeized treatment.
The obtained cross section is compared with the existing experimental results
at low energies. The $a_{2}(1320)$ production cross section at high energies
can be tested by the COMPASS experiment, which can provide important
information for clarifying the role of the Reggeized treatment at that energy
range. | hep-ph |
Quark distributions in polarized rho meson and its comparison with those
in pion: Valence quark distributions in transversally and longitudinally polarizied
rho mesons in the region of intermediate x are obtained by generalizied QCD sum
rules. Power corrections up to d=6 are taken into account. Comparison of the
results for pi and rho mesons shows, that polarization effects are very
significant and SU(6) symmetry of distribution functions is absent. The strong
suppression of quark and gluon sea distributions in longitudinally polarizied
rho mesons is found. | hep-ph |
The T7 flavor symmetry in 3-3-1 model with neutral leptons: We construct a 3-3-1 model based on non-Abelian discrete symmetry $T_7$
responsible for the fermion masses. Neutrinos get masses from only anti-sextets
which are in triplets $\underline{3}$ and $\underline{3}^*$ under $T_7$. The
flavor mixing patterns and mass splitting are obtained without perturbation.
The tribimaximal form obtained with the breaking $T_7 \rightarrow Z_3$ in
charged lepton sector and both $T_7 \rightarrow Z_3$ and $Z_3 \rightarrow
\{\mathrm{Identity}\}$ must be taken place in neutrino sector but only apart in
breakings $Z_3 \rightarrow \{\mathrm{Identity}\}$ (without contribution of
$\si'$), and the upper bound on neutrino mass $\sum_{i=1}^3m_i$ at the level is
presented. The Dirac CP violation phase $\delta$ is predicted to either
$\frac{\pi}{2}$ or $\frac{3\pi}{2}$ which is maximal CP violation. From the
Dirac CP violation phase we obtain the relation between Euler's angles which is
consistent with the experimental in PDG 2012. On the other hand, the realistic
lepton mixing can be obtained if both the direction for breakings $T_7
\rightarrow Z_3$ and $Z_3 \rightarrow \{\mathrm{Identity}\}$ are taken place in
neutrino sectors. The CKM matrix is the identity matrix at the tree-level. | hep-ph |
On holographic relation between radial meson trajectories and
deconfinement temperature: The interrelation between the deconfinement temperature of hadron medium and
parameters of radial Regge trajectories within the bottom-up holographic models
for QCD is scrutinized. We show that the lattice data on the deconfinement
temperature can yield a powerful restriction on the spectrum of excited mesons
and glueballs within the framework of holographic approach. The best
phenomenological agreement and theoretical self-consistency are achieved if the
scalar meson $f_0(1500)$ is considered as the lightest glueball. | hep-ph |
Improving NLO-parton shower matched simulations with higher order matrix
elements: In recent times the algorithms for the simulation of hadronic collisions have
been subject to two substantial improvements: the inclusion, within parton
showering, of exact higher order tree level matrix elements (MEPS) and,
separately, next-to-leading order corrections (NLOPS). In this work we examine
the key criteria to be met in merging the two approaches in such a way that the
accuracy of both is preserved, in the framework of the POWHEG approach to
NLOPS. We then ask to what extent these requirements may be fulfilled using
existing simulations, without modifications. The result of this study is a
pragmatic proposal for merging MEPS and NLOPS events to yield much improved
MENLOPS event samples. We apply this method to W boson and top quark pair
production. In both cases results for distributions within the remit of the NLO
calculations exhibit no discernible changes with respect to the pure NLOPS
prediction; conversely, those sensitive to the distribution of multiple hard
jets assume, exactly, the form of the corresponding MEPS results. | hep-ph |
Supersymmetric Large Extra Dimensions Are Small and/or Numerous: Recently, a scenario has been proposed in which the gravitational scale could
be as low as the TeV scale, and extra dimensions could be large and detectable
at the electroweak scale. Although supersymmetry is not a requirement of this
scenario, it is nevertheless true that its best-motivated realizations arise in
supersymmetric theories (like M theory). We argue here that supersymmetry can
have robust, and in some instances fatal, implications for the expected
experimental signature for TeV-scale gravity. The signature of the
supersymmetric version of the scenario differs most dramatically from what has
been considered in the literature because mass splittings within the gravity
supermultiplet in these models are extremely small, implying in particular the
existence of a very light spin-one superpartner for the graviton. We compute
the implications of this graviphoton, and show that it can acquire
dimension-four couplings to ordinary matter which can strongly conflict with
supernova bounds. | hep-ph |
The study of the negative pion production in neutron-proton collisions
at beam momenta below 1.8 GeV/c: A detailed investigation of the reaction np -> pp\pi^{-} has been carried out
using the data obtained with the continuous neutron beam produced by charge
exchange scattering of protons off a deuterium target. A partial wave
event-by-event based maximum likelihood analysis was applied to determine
contributions of different partial waves to the pion production process. The
combined analysis of the np -> pp\pi^{-} and pp -> pp\pi^{0} data measured in
the same energy region allows us to determine the contribution of isoscalar
partial waves (I=0) in the momentum range from 1.1 up to 1.8 GeV/c. The decay
of isoscalar partial waves into (^1S_0)_{pp}\pi$ channel provides a good tool
for a determination of the pp S-wave scalar scattering length in the final
state which was found to be a_{pp}=-7.5\pm 0.3 fm. | hep-ph |
Neutrino interactions with a weak slowly varying electromagnetic field: We derive the effective action for processes involving two neutrinos and two
photons at energies much below the electron mass. We discuss several
applications in which one or both photons are replaced by external fields. In
particular, Cherenkov radiation and neutrino pair production in weak external
fields are investigated for massive Dirac neutrinos. | hep-ph |
Comment on astrophysical consequences of a neutrinophilic 2HDM: Several authors have pointed out that the scalar-mediated interaction of
neutrinos in a neutriophilic two-Higgs-doublet model (nu2HDM) can be as strong
as electromagnetic interaction [1-3]. We show that the coupling constants of
neutrino-scalar interaction are actually restricted to be y_i < 1.5 x 10^{-3}
by supernova neutrino observation, and further constrained to be y_i < 2.3 x
10^{-4} by precision measurements of acoustic peaks of the cosmic microwave
background. Based on the energy-loss argument for supernova cores, we derive a
slightly more restrictive bound y_i < 3.5 x 10^{-5}. Therefore, the nu2HDM has
lost its spirit of explaining tiny Dirac neutrino masses while keeping neutrino
Yukawa couplings of order one. | hep-ph |
The Supersymmetric Standard Model, with a Brout-Englert-Higgs boson as
spin-0 partner of the Z: Supersymmetric extensions of the standard model lead us to expect
superpartners for all particles, spin-0 squarks and sleptons and spin-1/2
gluinos, charginos and neutralinos, with an odd R-parity making the lightest
one stable. The electroweak breaking is induced by a pair of spin-0 doublets,
leading to several charged and neutral BE-Higgs bosons. These theories also
lead to gauge/Higgs unification by providing spin-0 bosons as extra states for
spin-1 gauge bosons within massive gauge multiplets. In particular, the 125 GeV
boson recently observed at CERN, most likely a BE-Higgs boson associated with
the electroweak breaking, may also be interpreted, up to a mixing angle induced
by supersymmetry breaking, as the spin-0 partner of the Z under two
supersymmetry transformations. We also discuss how the compactification of
extra dimensions, relying on R-parity and other discrete symmetries, may
determine both the grand-unification and supersymmetry-breaking scales. | hep-ph |
Constraining Sterile Neutrino Interpretations of the LSND and MiniBooNE
Anomalies with Coherent Neutrino Scattering Experiments: Results from the LSND and MiniBooNE experiments have been interpreted as
evidence for a sterile neutrino with a mass near the electronvolt scale. Here
we propose to test such a scenario by measuring the coherent elastic scattering
rate of neutrinos from a pulsed spallation source. Coherent scattering is
universal across all active neutrino flavors, and thus can provide a
measurement of the total Standard Model neutrino flux. By performing
measurements over different baselines and making use of timing information, it
is possible to significantly reduce the systematic uncertainties and to
independently measure the fluxes of neutrinos that originate as $\nu_{\mu}$ or
as either $\nu_e$ or $\bar{\nu}_{\mu}$. We find that a 100 kg CsI detector
would be sensitive to the large fraction of the sterile neutrino parameter
space that could potentially account for the LSND and MiniBooNE anomalies. | hep-ph |
General Issues Connecting Flavor Symmetry and Supersymmetry: We motivate and construct supersymmetric theories with continuous flavor
symmetry, under which the electroweak Higgs doublets transform non-trivially.
Flavor symmetry is spontaneously broken at a large mass scale in a sector of
gauge-singlet fields; the light Higgs multiplets naturally emerge as special
linear combinations that avoid acquiring the generic large mass. Couplings of
the light Higgs doublets to light moduli fields from the singlet sector could
lead to important effects in the phenomenology of the Higgs sector. | hep-ph |
Gauge dependence of the on-shell renormalized mixing matrices: It was recently pointed out that the on-shell renormalization of the
Cabibbo-Kobayashi-Maskawa (CKM) matrix in the method by Denner and Sack causes
a gauge parameter dependence of the amplitudes. We analyze the gauge dependence
of the on-shell renormalization of the mixing matrices both for fermions and
scalars in general cases, at the one-loop level. We then show that this gauge
dependence can be avoided by fixing the counterterms for the mixing matrices in
terms of the off-diagonal wave function corrections for fermions and scalars
after a rearrangement, in a similar manner to the pinch technique for gauge
bosons. We finally present explicit calculation of the gauge dependence for two
cases: CKM matrix in the Standard Model, and left-right mixing of scalar quarks
in the minimal supersymmetric standard model. | hep-ph |
Distinguishing magnetic moment from oscillation solutions of the solar
neutrino problem with Borexino: Assuming that the observed deficit of solar neutrinos is due to the
interaction of their transition magnetic moment with the solar magnetic field
we derive the predictions for the forthcoming Borexino experiment. Three
different model magnetic field profiles which give very good global fits of the
currently available solar neutrino data are used. The expected signal at
Borexino is significantly lower than those predicted by the LMA, LOW and VO
neutrino oscillation solutions of the solar neutrino problem. It is similar to
that of the SMA oscillation solution which, however, is strongly disfavoured by
the Super-Kamiokande data on day and night spectra and zenith angle
distribution of the events. Thus, the neutrino magnetic moment solution of the
solar neutrino problem can be unambiguously distinguished from the currently
favoured oscillation solutions at Borexino. | hep-ph |
Heavy hybrid mesons in the QCD sum rule: We study the spectra of the hybrid mesons containing one heavy quark
($q\bar{Q}g$) within the framework of QCD sum rules in the heavy quark limit.
The derived sum rules are stable with the variation of the Borel parameter
within their corresponding working ranges. The extracted binding energy for the
heavy hybrid doublets $H^h(S^h)$ and $M^h(T^h)$ is almost degenerate. We also
calculate the pionic couplings between these heavy hybrid and the conventional
heavy meson doublets using the light-cone QCD sum rule method. The extracted
coupling constants are rather small as a whole. With these couplings we make a
rough estimate of the partial widths of these pionic decay channels. | hep-ph |
MSSM at future Higgs factories: In this work, we study the implication of Higgs precision measurements at
future Higgs factories on the MSSM parameter space, focusing on the dominant
stop sector contributions. We perform a multi-variable fit to both the signal
strength for various Higgs decay channels at Higgs factories and the Higgs
mass. The chi-square fit results show sensitivity to mA, tan beta, stop mass
parameter mSUSY as well as the stop left-right mixing parameter Xt. We also
study the impact of the Higgs mass prediction on the MSSM and compare the
sensitivities of different Higgs factories. | hep-ph |
Test of beta and antineutrino spectra symmetry in beta-decay: The mechanism of beta decay in nature is not understood yet. Mirrored energy
spectra of electron and antineutrino can clarify the situation. A special
experiment is needed to measure antineutrino spectrum from known beta-decaying
isotope to compare it with the beta one. One of ongoing experiments with large
volume detector can be chosen to make the experiment. Another possibility is to
make a special experiment close to a powerful source of mixture of known
beta-decaying isotopes. If sufficient differences in shape will be observed the
method of antineutrino spectrum calculation should be revised. | hep-ph |
Color-Octet $ψ'$ Production at Low $p_\perp$: We study contributions from color-octet quarkonium formation mechanisms to
$p_\perp$-integrated $\psi'$ production cross sections in pion-nucleon
reactions. The observed polarization of the $\psi'$ is not reproduced by the
lowest-order leading-twist color-singlet and color-octet mechanisms. This
suggests that there are important quarkonium production mechanisms beyond
leading twist. | hep-ph |
B-Mesons on the Transverse Lattice: We present results from a first study of $B$-mesons that is based on a
transverse lattice formulation of light-front QCD. The shape of the Isgur-Wise
form factor is in very good agreement with experimental data. However, the
calculations yield rather large values for $f_B$ and $\bar{\Lambda}$ compared
to contemporary calculations based on other techniques. | hep-ph |
Seesaw and the Riddle of Mass: The prediction of small neutrino masses through the Seesaw Mechanism and
their subsequent measurement suggests that the natural cut-off of the Standard
Model is very high indeed. The recent neutrino data must be interpreted as a
reflection of physics at very high energy. We examine their implications in
terms of ideas of Grand Unification and Supersymmetry, and as possible hints
for a unified theory of flavor. | hep-ph |
Neutrino Oscillometry: Neutrino oscillations are studied employing sources of low energy
monoenergetic neutrinos following electron capture by the nucleus and measuring
electron recoils. Since the neutrino energy is very low the oscillation length
appearing in this electronic neutrino disappearance experiment can be so small
that the full oscillation can take place inside the detector. Thus one may
determine very accurately all the neutrino oscillation parameters. In
particular one can measure or set a better limit on the unknown parameter
theta13. One, however, has to pay the price that the expected counting rates
are very small. Thus one needs a very intensive neutrino source and a large
detector with as low as possible energy threshold and high energy and position
resolution. Both spherical gaseous and cylindrical liquid detectors are
studied. Different source candidates are considered | 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 |
Polarization puts a New Spin on Physics: Polarization and spin effects are useful for probing the Standard Model, in
both the electroweak sector and the strong sector, where the spin decomposition
of the nucleon is still a hot topic, with important new data on the net
polarizations of the gluon and the strange quarks. Spin phenomena are also
useful in searches for new physics, for example via measurements of the
anomalous magnetic moment of the muon and searches for electric dipole moments.
The cross sections for the direct detection of dark matter may also have an
important spin-dependent component, related to the spin decomposition of the
nucleon, that could be an important diagnostic tool. Polarization effects are
also important diagnostic aids for high-energy experiments at electron-proton,
proton-proton and electron-positron colliders. | hep-ph |
High energy photon production in strong colliding laser beams: The collision of two intense, low-frequency laser beams is considered. The
$e^-e^+$ pairs created in this field are shown to exhibit recollisions, which
take place at high energy accumulated due to the wiggling of fermions. The
resulting $e^-e^+$ annihilation produces high energy photons, or heavy
particles. The coherent nature of the laser field provides strong enhancement
of the probability of these events. Analytical and numerical results are
outlined. | hep-ph |
Out-of-Equilibrium Photon Production in the Late Stages of Relativistic
Heavy-Ion Collisions: In this work, we assess the importance of non-equilibrium dynamics in the
production of photons from the late stages of relativistic heavy-ion
collisions. The p$_\mathrm{T}$-differential spectra and $v_2$ of photons from
the late hadronic stage are computed within a non-equilibrium hadron transport
approach, and compared to the results of a local equilibrium evolution using
ideal relativistic hydrodynamics. It is found that non-equilibrium dynamics
enhance the late-stage photon production at low p$_\mathrm{T}$ and decreases it
at higher p$_\mathrm{T}$ compared to the estimate from hydrodynamics. This same
comparison points to a significant increase in the momentum anisotropies of
these photons due to non-equilibrium dynamics. Once combined with photons
produced above the particlization temperature in the hydrodynamics evolution,
the differences between the two approaches appear modest in what concerns the
p$_\mathrm{T}$ differential spectra, but are clearly noticeable at low
p$_\mathrm{T}$ for the elliptic flow: non-equilibrium dynamics enhance the
photon $v_2$ below p$_\mathrm{T}$ $\approx 1.4$ GeV. | hep-ph |
Measuring Slepton Masses and Mixings at the LHC: Flavor physics may help us understand theories beyond the standard model. In
the context of supersymmetry, if we can measure the masses and mixings of
sleptons and squarks, we may learn something about supersymmetry and
supersymmetry breaking. Here we consider a hybrid gauge-gravity supersymmetric
model in which the observed masses and mixings of the standard model leptons
are explained by a U(1) x U(1) flavor symmetry. In the supersymmetric sector,
the charged sleptons have reasonably large flavor mixings, and the lightest is
metastable. As a result, supersymmetric events are characterized not by missing
energy, but by heavy metastable charged particles. Many supersymmetric events
are therefore fully reconstructible, and we can reconstruct most of the charged
sleptons by working up the long supersymmetric decay chains. We obtain
promising results for both masses and mixings, and conclude that, given a
favorable model, precise measurements at the LHC may help shed light not only
on new physics, but also on the standard model flavor parameters. | hep-ph |
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