HEP Phenomenology·hep-ph
54 papers—34 primary·20 cross-listed·reconstructed*
Marco S. Bianchi🇬🇧 · Matias Leoni🇦🇷
We consider a planar doublebox with four massive external momenta and two massive internal propagators. We derive the system of differential equations for the relevant master integrals, cast it in canonical form, write it as a form and solve it in terms of iterated integrals up to depth four.
Timothy Cohen🇺🇸 · Kohta Murase🇺🇸 · Nicholas L. Rodd🇺🇸 · Benjamin R. Safdi🇺🇸 · Yotam Soreq🇺🇸
Utilizing the Fermi measurement of the gamma-ray spectrum toward the Galactic Center, we derive some of the strongest constraints to date on the dark matter (DM) lifetime in the mass range from hundreds of MeV to above an EeV. Our profile-likelihood based analysis relies on 413 weeks of Fermi Pass 8 data from 200 MeV to 2 TeV, along with up-to-date models for diffuse gamma-ray emission within the Milky Way. We model Galactic and extragalactic DM decay and include contributions to the DM-induced gamma-ray flux resulting from both primary emission and inverse-Compton scattering of primary electrons and positrons. For the extragalactic flux, we also calculate the spectrum associated with cascades of high-energy gamma-rays scattering off of the cosmic background radiation. We argue that a decaying DM interpretation for the 10 TeV-1 PeV neutrino flux observed by IceCube is disfavored by our constraints. Our results also challenge a decaying DM explanation of the AMS-02 positron flux. We interpret the results in terms of individual final states and in the context of simplified scenarios such as a hidden-sector glueball model.
Hooman Davoudiasl🇺🇸 · Pier Paolo Giardino🇺🇸 · Cen Zhang🇺🇸
The exo-Higgs model can accommodate a successful baryogenesis mechanism that closely mirrors electroweak baryogenesis in the Standard Model, but avoids its shortcomings. We extend the exo-Higgs model by the addition of a singlet complex scalar . In our model, can be a viable asymmetric dark matter (ADM) candidate. We predict the mass of the ADM particle to be . The leptophilic couplings of can provide for efficient annihilation of the ADM pairs. We also discuss the LHC signals of our scenario, and in particular the production and decays of exo-leptons which would lead to "lepton pair plus missing energy" final states. Our model typically predicts potentially detectable gravitational waves originating from the assumed strong first order phase transition at a temperature of TeV. If the model is further extended to include new heavy vector-like fermions, {\it e.g.} from an ultraviolet extension, couplings could explain the muon anomaly.
Gabriel Magill🇨🇦 · Ryan Plestid🇨🇦
We have calculated cross sections for the production of lepton pairs by a neutrino incident on a nucleus using both the equivalent photon approximation, and deep inelastic formalism. We find that production of mixed flavour lepton pairs can have production cross sections as high as 35 times those of the traditional muon pair-production process. Rates are estimated for the SHiP and DUNE intensity frontier experiments. We find that multiple trident production modes, some of which have never been observed, represent observable signals over the lifetime of the detectors. Our estimates indicate that the SHiP collaboration should be able to observe on the order of 300 trident events given POT, and that the DUNE collaboration can expect approximately 250 trident events in their near detector given 3X10^{22} POT. We also discuss possible applications of the neutrino trident data to be collected at SHiP and DUNE for SM and BSM physics.
Jose Bernabeu🇪🇸 · Francisco J. Botella (Valencia U. & IFIC)🇪🇸 · Nick E. Mavromatos (King's Coll. London)🇬🇧 · Miguel Nebot (CFTP Lisbon & IST)🇵🇹
In the presence of quantum gravity fluctuations (space-time foam), the CPT operator may be ill-defined. Its perturbative treatment leads to a modification of the Einstein-Podolsky-Rosen correlation of the neutral meson system by adding an Entanglement-weakening term of the wrong exchange symmetry, the -effect. In the current paper we identify how to probe the complex in the entangled -system using Flavour(f)-CP(g) eigenstate decay channels: the connection between the Intensities for the two time-ordered decays (f, g) and (g, f) is lost. Appropriate observables are constructed allowing independent experimental determinations of Re() and Im(), disentangled from CPT violation in the evolution Hamiltonian Re() and Im(). 2- tensions for both Re() and Im() are shown to be uncorrelated.
Materials with charged chiral quasiparticles in external parallel electric and magnetic fields can support an electric current that grows linearly in time, corresponding to diverging DC conductivity. From experimental viewpoint, this "Chiral Magnetic Superconductivity" (CMS) is thus analogous to conventional superconductivity. However the underlying physics is entirely different -- the CMS does not require a condensate of Cooper pairs breaking the gauge degeneracy, and is thus not accompanied by Meissner effect. Instead, it owes its existence to the (temperature-independent) quantum chiral anomaly and the conservation of chirality. As a result, this phenomenon can be expected to survive to much higher temperatures. Even though the chirality of quasiparticles is not strictly conserved in real materials, the chiral magnetic superconductivity should still exhibit itself in AC measurements at frequencies larger than the chirality-flipping rate, and in microstructures of Dirac and Weyl semimetals with thickness below the mean chirality-flipping length that is about 1-100 m. In nuclear physics, the CMS should contribute to the charge-dependent elliptic flow in heavy ion collisions.
Over the past years, the topic of the nucleon's nonperturbative or charm (IC) content has enjoyed something of a renaissance, largely motivated by theoretical developments involving quark modelers and PDF fitters. In this talk I will briefly describe the importance of intrinsic charm to various issues in high-energy phenomenology, and survey recent progress in constraining its overall normalization and contribution to the momentum sum rule of the nucleon. I end with the conclusion that progress on the side of calculation has now placed the onus on experiment to unambiguously resolve the proton's intrinsic charm component.
Christopher Karwin🇺🇸 · Simona Murgia🇺🇸 · Tim M.P. Tait🇺🇸 · Troy A. Porter🇺🇸 · Philip Tanedo🇺🇸
The center of the Milky Way is predicted to be the brightest region of gamma-rays generated by self-annihilating dark matter particles. Excess emission about the Galactic center above predictions made for standard astrophysical processes has been observed in gamma-ray data collected by the Fermi Large Area Telescope. It is well described by the square of an NFW dark matter density distribution. Although other interpretations for the excess are plausible, the possibility that it arises from annihilating dark matter is valid. In this paper, we characterize the excess emission as annihilating dark matter in the framework of an effective field theory. We consider the possibility that the annihilation process is mediated by either pseudo-scalar or vector interactions and constrain the coupling strength of these interactions by fitting to the Fermi Large Area Telescope data for energies 1-100 GeV in the 15 x 15 degree region about the Galactic center using self-consistently derived interstellar emission models and point source lists for the region. The excess persists and its spectral characteristics favor a dark matter particle with a mass in the range approximately from 50 to 190 (10 to 90) GeV and annihilation cross section approximately from 1E-26 to 4E-25 (6E-27 to 2E-25) cm^3/s for pseudo-scalar (vector) interactions. We map these intervals into the corresponding WIMP-neutron scattering cross sections and find that the allowed range lies well below current and projected direct detection constraints for pseudo-scalar interactions, but are typically ruled out for vector interactions.
Kari J. Eskola🇫🇮 · Petja Paakkinen🇫🇮 · Hannu Paukkunen🇫🇮 · Carlos A. Salgado🇪🇸
We introduce a global analysis of collinearly factorized nuclear parton distribution functions (PDFs) including, for the first time, data constraints from LHC proton-lead collisions. In comparison to our previous analysis, EPS09, where data only from charged-lepton-nucleus deep inelastic scattering (DIS), Drell-Yan (DY) dilepton production in proton-nucleus collisions and inclusive pion production in deuteron-nucleus collisions were the input, we now increase the variety of data constraints to cover also neutrino-nucleus DIS and low-mass DY production in pion-nucleus collisions. The new LHC data significantly extend the kinematic reach of the data constraints. We now allow much more freedom for the flavour dependence of nuclear effects than in other currently available analyses. As a result, especially the uncertainty estimates are more objective flavour by flavour. The neutrino DIS plays a pivotal role in obtaining a mutually consistent behaviour for both up and down valence quarks, and the LHC dijet data clearly constrain gluons at large momentum fraction. Mainly for insufficient statistics, the pion-nucleus DY and heavy gauge boson production in proton-lead collisions impose less visible constraints. The outcome - a new set of next-to-leading order nuclear PDFs called EPPS16 - is made available for applications in high-energy nuclear collisions.
Moritz Greif🇩🇪 · Florian Senzel🇩🇪 · Heiner Kremer🇩🇪 · Kai Zhou🇩🇪 · Carsten Greiner🇩🇪 · Zhe Xu🇨🇳
We discuss the implementation of leading-order photon production in nonequilibrium partonic transport simulations. In this framework photons are produced by microscopic scatterings, where we include the exact matrix elements of Compton scattering, quark-antiquark annihilation, and bremsstrahlung processes. We show how the hard-thermal loop inspired screening of propagators has to be modified such that the microscopic production rate agrees well with the analytically known resummed leading-order rate. We model the complete quark-gluon plasma phase of heavy-ion collisions by using the partonic transport approach called the Boltzmann approach to multiparton scatterings (BAMPS), which solves the ultrarelativistic Boltzmann equation with Monte Carlo methods. We show photon spectra and elliptic flow of photons from BAMPS and discuss nonequilibrium effects. Due to the slow quark chemical equilibration in BAMPS, the yield is lower than the results from other groups; in turn we see a strong effect from scatterings of energetic jet-like partons with the medium. This nonequilibrium photon production can dominate the thermal emission, such that the spectra are harder and the photonic elliptic flow of the quark-gluon plasma becomes negative.
Sanjin Benic🇯🇵 · Kenji Fukushima🇯🇵 · Oscar Garcia-Montero🇩🇪 · Raju Venugopalan🇺🇸
We report on a first NLO computation of photon production in p+A collisions at collider energies within the Color Glass Condensate framework, significantly extending previous LO results. At central rapidites, our result is the dominant contribution and probes multi-gluon correlators in nuclei. At high photon momenta, the result is directly sensitive to the nuclear gluon distribution. The NLO result contains two processes, the annihilation process and the process with pair and a photon in the final state. We provide a numerical evaluation of the photon spectrum from the annihilation process.
Andre Sopczak (Institute of Experimental and Applied Physics, Czech Technical University in Prague)🇨🇿
After the discovery of a Higgs boson, the measurements of its properties are at the forefront of research. The determination of the associated production of a Higgs boson and a pair of top quarks is of particular importance as the ttH Yukawa coupling is large and thus an excellent probe for physics beyond the Standard Model (SM). For the complete LHC Run-1 dataset, the combined ATLAS and CMS signal strength (defined as the ratio of measured cross-section to the SM prediction) was , which indicated a mild excess with respect to the SM expectation. The results of the ttH search with multilepton and diphoton signatures are presented for the first LHC Run-2 data (13 fb at 13 TeV) recorded by the ATLAS experiment: for the multilepton analyses and for the diphoton analyses. Both measurements are in agreement with the SM expectation.
Wei Dai🇨🇳 · Ben-Wei Zhang🇨🇳
The suppression of the productions of the meson in relativistic heavy-ion collisions and its ratio of are computed theoretically in the framework of the perturbative QCD(pQCD) to confront the experimental data which matches well. We explore how the hadron production ratios as would further disclose the informations of the production suppressions due to the energy loss of the energetic jet that propagating though the QGP medium. Also, we present our further studies on vector mesons such as and within the same framework. The theoretical predictions based on pQCD are thus firstly given which give a decent description on the experimental measurements. It paved the way to the uniformly understanding of the strong suppression of single hadron productions at large transverse momentum which is a convincing evidence of the jet quenching effect.
M. Cristina Diamantini🇮🇹 · Dmitri E. Kharzeev🇺🇸 · Alexander Molochkov🇷🇺 · Thomas Schaefer🇺🇸 · Tin Sulejmanpasic🇫🇷
We discuss a number of examples for recent connections between emergent phenomena in many-body systems in atomic and condensed matter physics, and confinement and other non-perturbative effects in quantum chromodynamics.
The vectorlike top partners are predicted in many extensions of the Standard Model (SM). In a simplified model including a single vectorlike quark with charge , we investigate the process induced by the couplings between the top partner with the first and the third generation quarks at the LHC. We find that the mixing with the first generation can enhance the production cross section. We further study the observability of the single heavy top partner through the process at the high-luminosity~(HL)-LHC~(a 14 TeV collider with an integrated luminosity of 3 ab). For three typical heavy quark masses and 1000 GeV, the exclusion limits, as well as the discovery reach in the parameter plane of the two variables , are respectively obtained at the HL-LHC.
We present the first ever AdS/CFT calculation of for a light quark jet as a function of position or, equivalently, time. Our result does not suffer from the gamma factor blow up of the usual time-independent AdS/CFT heavy quark setup and is qualitatively similar to, but differs by factor from, the light flavor result of Liu, Rajagopal, and Wiedemann. Our findings can be immediately implemented into any -based energy loss model. Our derivation relies on our calculation of the average distance squared, , travelled by the endpoint of a string falling in an AdS-Schwarzschild spacetime. The early time behavior is ballistic, , but the late time behavior is the usual diffusive Brownian motion, . These late time dynamics are universal and depend only on the near-horizon physics, which allows us to generalize our results to arbitrary dimensions and thus make contact with the physics explored by RHIC and LHC. Additionally, we find that AdS/CFT predicts angular ordering for radiation in medium, just as in vacuum, and in contradistinction to weak-coupling, with its anti-angular ordering prediction. Finally, our results also imply, sensibly, that AdS/CFT predicts a smooth interpolation between the angular correlations of open heavy flavor and light flavor observables.
N.Yu. Chernikova🇷🇺 · A.V. Kotikov🇷🇺
We present a set of formulas to extract the gluon density from the Berger-Block-Tan form of the deep inelastic structure function F2 at small x in the leading order of perturbation theory.
Dan Wang🇨🇳 · Rong-Gang Ping🇨🇳 · Lei Li🇨🇳 · Xiao-Rui Lyu🇨🇳 · Yang-Heng Zheng🇨🇳
We propose to measure the decay asymmetry parameters in the hadronic weak decays of singly charmed baryons, such as , and . The joint angular formulae for these processes are presented, and are used to extract the asymmetry parameters in annihilation data. Base on the current data set collected at BESIII, we estimate the experimental sensitivities to measure the parameters for , for and for .
Ya Li🇨🇳 · Ai-Jun Ma🇨🇳 · Zhen-Jun Xiao🇨🇳 · Wen-Fei Wang🇨🇳
In this work, we calculate the -averaged branching ratios and the direct -violating asymmetries of the quasi-two-body decays by employing the perturbative QCD (PQCD) approach (here stands for a light pseudoscalar meson or ). The vector current time-like form factor , which contains the final state interactions between the pion pair in the resonant region associated with the -wave states along with the two-pion distribution amplitudes, are employed to describe the interactions between the and the pion pair under the hypothesis of the conserved vector current. We found that (a) the PQCD predictions for the branching ratios and the direct -violating asymmetries for most considered decays agree with currently available data within errors; (b) for , the PQCD prediction is much smaller than the measured one; and (c) for decay mode, we found a negative asymmetry , which agrees with other theoretical predictions but different in sign from those as reported by BaBar and LHCb Collaboration.
E. Accomando🇬🇧 · L. Delle Rose🇬🇧 · S. Moretti🇬🇧 · E. Olaiya🇬🇧 · C. Shepherd-Themistocleous🇬🇧
We examine the observability of heavy neutrino (nu_h) signatures of a U(1)' enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the the Large Hadron Collider (LHC). We show that heavy neutrinos can be rather long-lived particles producing distinctive displaced vertices that can be accessed in the CERN LHC detectors. We concentrate here on the gluon fusion production mechanism gg -> H_{1,2} -> nu_h nu_h, where H_1 is the discovered SM-like Higgs and H_2 is a heavier state, yielding displaced leptons following nu_h decays into weak gauge bosons. Using data collected by the end of the LHC Run 2, these signatures would prove to be accessible with negligibly small background.
In this paper I investigate the analytic properties of the quark propagator Dyson-Schwinger equation (DSE) in the Landau gauge. In the quark self-energy, the combined gluon propagator and quark-gluon vertex is modeled by an effective interaction (the so-called Maris-Tandy interaction), where the ultraviolet term is neglected. This renders the loop integrand of the quark self-energy analytic on the cut-plane -Pi < arg(x) < Pi of the square of the external momentum. Exploiting the simplicity of the truncation, I study solutions of the quark propagator in the domain x in [-5.1,0] GeV^2 X i[0,10.2] GeV^2. Because of a complex conjugation symmetry, this region fully covers the parabolic integration domain for Bethe-Salpeter equations (BSEs) for bound state masses of up to 4.5 GeV. Employing a novel numerical technique that is based on highly parallel computation on graphics processing units (GPUs), I extract more than 6500 poles in this region, which arise as the bare quark mass is varied over a wide range of closely spaced values. The poles are grouped in 23 individual 'trajectories', that capture the movement of the poles in the complex region as the bare mass is varied. The raw data of the pole locations and -residues is provided as supplemental material, which can be used to parametrize solutions of the complex quark propagator for a wide range of bare mass values and for large bound state masses. This study is a first step towards an extension of previous work on the analytic continuation of perturbative one-loop integrals, with the long-term goal of establishing a framework that allows for the numerical extraction of the analytic properties of the quark propagator with a truncation that extends beyond the rainbow by making adequate adjustments in the contour of the radial integration of the quark self-energy.
M. A. Hernández-Ruíz🇲🇽 · A. Gutiérrez-Rodríguez🇲🇽 · A. González-Sánchez🇲🇽
We calculate the stellar energy loss due to neutrino-pair production in annihilation in the context of a 331 model, a left-right symmetric model and a simplest little Higgs model in a way that can be used in supernova calculations. We also present some simple estimates which show that such process can act as an efficient energy loss mechanism in the shocked supernova core. We find that the stellar energy loss is almost independent on the parameters of the models in the allowed range for these parameters. This work complements other studies on the stellar energy loss rate in annihilation.
Liang-Liang Liu🇨🇳 · Chao Wang🇨🇳 · Ying Liu🇨🇳 · Xin-Heng Guo🇨🇳
The heavy baryon is regarded as composed of a heavy quark and a scalar diquark which has good spin and isospin quantum numbers. In this picture, we calculate the electromagnetic (EM) form factors of in the Bethe-Salpeter equation approach. We find that the shapes of the EM form factors of are similar to those of , which have a peak at about , but the amplitudes are much smaller than those of .
B.I. Ermolaev🇷🇺 · S.I. Troyan🇷🇺
In this paper we argue for existence of an intrinsic mass scale in QCD factorization and present a possible origin of it. Values of this scale are within the Non-Perturbative QCD mass range. It differs from the known factorization scale which is within the perturbative mass range and dependence on which vanishes in the factorization convolutions. We show that the intrinsic mass scale plays the key part in reduction of KT Factorization to Collinear Factorization: such a reduction can be done provided that dependence of the non-perturbative inputs in KT Factorization on invariant energy has a sharp-peaked form. In this case the intrinsic mass scale is associated with location of the peak(s). We also present models where the intrinsic scale is generated by such peaks.
G. Lazarides🇬🇷 · C. Panagiotakopoulos🇬🇷 · Q.Shafi🇺🇸
We show how successful supersymmetric hybrid inflation is realized in realistic models where the resolution of the minimal supersymmetric standard model mu problem is intimately linked with axion physics. The scalar fields that accompany the axion, such as the saxion, are closely monitored during and after inflation to ensure that the axion isocurvature perturbations lie below the observational limits. The scalar spectral index n_s is about 0.96 - 0.97, while the tensor-to-scalar ratio r, a canonical measure of gravity waves, lies well below the observable range in our example. The axion domain walls are inflated away, and depending on the axion decay constant f_a and the magnitude of the mu parameter, the axions and/or the lightest supersymmetric particle compose the dark matter in the universe. Non-thermal leptogenesis is naturally implemented in this class of models.
G. Aliferis🇬🇷 · G.K. Leontaris🇬🇷 · N.D. Vlachos🇬🇷
The investigation of the role of finite groups in flavor physics and particularly, in the interpretation of the neutrino data has been the subject of intensive research. Motivated by this fact, in this work we derive the three-dimensional unitary representations of the projective linear group PSL_2(7). Based on the observation that the generators of the group exhibit a latin square pattern, we use available computational packages on discrete algebra to determine the generic properties of the group elements. We present analytical expressions and discuss several examples which reproduce the neutrino mixing angles in accordance with the experimental data.
Maxim Dvornikov (IZMIRAN, Tomsk State University)🇷🇺
We study the generation of strong large scale magnetic fields in compact stars containing degenerate quark matter with unbroken chiral symmetry. The magnetic field growth is owing to the magnetic field instability driven by the electroweak interaction of quarks. In this system we predict the enhancement of the seed magnetic field to the strengths . In our analysis we use the typical parameters of the quark matter in the core of a hybrid star or in a quark star. We also apply of the obtained results to model the generation of magnetic fields in magnetars.
If observed, charged lepton flavour violation is a clear sign of new physics - beyond the Standard Model minimally extended to accommodate neutrino oscillation data. After a brief review of several charged lepton flavour violation observables and their current experimental status, we consider distinct extensions of the Standard Model which could potentially give rise to observable signals, focusing on the case of models in which the mechanism of neutrino mass generation is the common source of neutral and charged lepton flavour violation.
Stanislaw D. Glazek🇵🇱 · Arkadiusz P. Trawinski🇵🇱
The concept of effective particles is introduced in the Minkowski space-time Hamiltonians in quantum field theory using a new kind of the relativistic renormalization group procedure that does not integrate out high-energy modes but instead integrates out the large changes of invariant mass. The new procedure is explained using examples of known interactions. Some applications in phenomenology, including processes measurable in colliders, are briefly presented.
Albert Escrivà🇪🇸 · Cristiano Germani🇪🇸
Naïve dimensional analysis seems to suggest possible unitarity violations in the framework of the Higgs and new Higgs inflationary scenarios. These violations seem to happen around the value in which the potential energy, per given Higgs boson's vacuum expectation value, crosses the perturbative cut-off scale calculated around the electroweak vacuum. Conversely to these expectations, in this paper we show that, by using an exact analysis of the background dependent cut-off scale, and by including the contribution of the phase-space volume in the perturbative scattering amplitudes, no violation of (perturbative) unitarity might ever happen during the whole Universe evolution.
V. P. Goncalves🇧🇷 · B. D. Moreira🇧🇷 · F. S. Navarra🇧🇷
In this letter we update our predictions for exclusive and photoproduction in proton-proton and nucleus - nucleus collisions at the Run 2 LHC energies obtained with the color dipole formalism and considering the impact parameter Color Glass Condensate model (bCGC) for the forward dipole - target scattering amplitude. A comparison with the LHCb data on rapidity distributions and photon - hadron cross sections is presented. Our results demonstrate that the current data can be quite well described by the bCGC model, which takes into account nonlinear effects in the QCD dynamics and reproduces the very precise HERA data, without introducing any additional effect or free parameter.
Javier L. Albacete🇪🇸 · Hannah Petersen🇩🇪 · Alba Soto-Ontoso🇪🇸
We investigate the effect of non-trivial spatial correlations between proton constituents, considered in this work to be gluonic hot spots, on the initial conditions of proton-proton collisions from ISR to LHC energies, i.e. GeV. The inclusion of these correlations is motivated by their fundamental role in the description of a recently observed new feature of scattering at TeV, the hollowness effect. Our analysis relies on a Monte-Carlo Glauber approach including fluctuations in the hot spot positions and their entropy deposition in the transverse plane. We explore both the energy dependence and the effect of spatial correlations on the number of wounded hot spots, their spatial distribution and the eccentricities, , of the initial state geometry of the collision. In minimum bias collisions we find that the inclusion of short range repulsive correlations between the hot spots reduces the value of the eccentricity () and the triangularity (). In turn, upon considering only the events with the highest entropy deposition i.e. the ultra-central ones, the probability of having larger increases significantly in the correlated scenario. Finally, the eccentricities show a quite mild energy dependence.
Piotr Lebiedowicz🇵🇱 · Otto Nachtmann🇩🇪 · Antoni Szczurek🇵🇱
We consider the and processes at LHC energies. Our description is based on the nonperturbative framework of tensor pomeron and tensor reggeon exchanges. We discuss the Drell-Hiida-Deck type mechanism with centrally produced meson associated with a very forward/backward system. The considered processes constitute an inelastic (non-exclusive) background to the reaction in the case when only the centrally produced meson decaying into is measured, the final state protons are not observed, and only rapidity-gap conditions are checked experimentally. We compare our results for the reaction with the experimental data obtained by the H1 collaboration at HERA. We present several differential distributions for the reaction and estimate the size of the proton dissociative background to the exclusive process. The ratio of integrated cross sections for the inelastic processes, where stands for plus , to the reference reaction is of order of (7--10)\%. We present also the ratios of the rapidity and transverse momentum distributions for the inelastic versus the elastic reaction. Our results may be used to investigate the process at LHC energies.
Roberto Fiore🇮🇹 · Laszlo Jenkovszky🇺🇦 · Rainer Schicker🇩🇪
A model for exclusive diffractive resonance production in proton-proton collisions at LHC energies is presented. This model is based on the convolution of the Donnachie-Landshoff parameterisation of Pomeron flux in the proton with the Pomeron cross section for resonance production. The hadronic cross section for f(980) and f(1270) production at midrapidity is given differentially in mass and transverse momentum of the resonance. The proton fractional longitudinal momentum loss is presented.
We answer to 72 frequently asked questions about theories of multifractional spacetimes. Apart from reviewing and reorganizing what we already know about such theories, we discuss the physical meaning and consequences of the very recent flow-equation theorem on dimensional flow in quantum gravity, in particular its enormous impact on the multifractional paradigm. We will also get some new theoretical results about the construction of multifractional derivatives and the symmetries in the yet-unexplored theory , the resolution of ambiguities in the calculation of the spectral dimension, the relation between the theory with -derivatives and the theory with fractional derivatives, the interpretation of complex dimensions in quantum gravity, the frame choice at the quantum level, the physical interpretation of the propagator in as an infinite superposition of quasiparticle modes, the relation between multifractional theories and quantum gravity, and the issue of renormalization, arguing that power-counting arguments do not capture the exotic properties of extreme UV regimes of multifractional geometry, where may indeed be renormalizable. A careful discussion of experimental bounds and new constraints are also presented.
Nicola Tomassetti🇮🇹 · Jie Feng🇨🇳
A new analysis of cosmic ray (CR) data collected by the SOKOL experiment in space found that the deuteron-to-helium ratio at energies between 500 and 2000 GeV/nucleon takes the value d/He ~ 1.5. As we will show, this result cannot be explained by standard models of secondary CR production in the interstellar medium and points to the existence of a high-energy source of CR deuterons. To account for the deuteron excess in CRs, we argue that the only viable solution is hadronic interaction processes of accelerated particles inside old supernova remnants (SNRs). From this mechanism, however, the B/C ratio is also expected to increase at energy above ~50 of GeV/nucleon, in conflict with new precision data just released by the AMS-02 experiment. Hence, if this phenomenon is a real physical effect, hadronic production of CR deuterons must occur in SNRs characterized by low metal abundance. In such a scenario, the sources accelerating C-N-O nuclei are not the same as those accelerating helium or protons, so that the connection between d/He ratio and B/C ratio is broken, and the latter cannot be used to place constraints on the production of light isotopes or antiparticles.
Hou-Jun Lü🇨🇳 · Hai-Ming Zhang🇨🇳 · Shu-Qing Zhong🇨🇳 · Shu-Jin Hou🇨🇳 · Hui Sun🇨🇳 · Jared Rice🇺🇸 · En-Wei Liang🇨🇳
GRB 160821B is a short gamma-ray burst (GRB) at redshift , with a duration less than 1 second and without detection of any "extended emission" up to more than 100 seconds in both {\em Swift}/BAT and {\em Fermi}/GBM bands. An X-ray plateau with a sharp drop 180 seconds after the BAT trigger was observed with {\em Swift}/XRT. No supernova or kilo-nova signature was detected. Assuming the central engine of this SGRB is a recently born supra-massive magnetar, we can explain the SGRB as jet radiation and its X-ray plateau as the internal energy dissipation of the pulsar wind as it spins down. We constrain its surface magnetic field as G and initial spin period as seconds. Its equation of state is consistent with the GM1 model with and ellipticity . Its gravitational wave (GW) radiation may be detectable with the future Einstein Telescope, but is much weaker than the current detectability limit of advanced-LIGO. The GW radiation of such an event would be detectable by advanced-LIGO if it occurred at a distance of 100 Mpc ().
Yan Gong🇨🇳 · Xuelei Chen🇨🇳 · Hua Feng🇨🇳
The recently measured 3.5 keV line in a number of galaxy clusters, the Andromeda galaxy (M31) and the Milky Way (MW) center can be well accounted for by a scenario in which dark matter decays to axion-like particles (ALPs) and subsequently convert to 3.5 keV photons in magnetic fields of galaxy clusters or galaxies. We propose to test this hypothesis by performing X-ray polarization measurements. Since ALPs can only couple to photons with polarization orientation parallel to magnetic field, we can confirm or reject this model by measuring the polarization of 3.5 keV line and comparing it to the orientation of magnetic field. We discuss luminosity and polarization measurements for both galaxy cluster and spiral galaxy, and provide a general relation between polarization and galaxy inclination angle. This effect is marginally detectable with X-ray polarimetry detectors currently under development, such as the enhanced X-ray Timing and Polarization (eXTP), the Imaging X-ray Polarimetry Explorer (IXPE) and the X-ray Imaging Polarimetry Explorer (XIPE). The sensitivity can be further improved in the future with detectors of larger effective area or better energy resolutions.
We study the tensor consistency relation in models of axion inflation with an SU(2) gauge field. In the tensor sector, we have two spin-2 modes, the standard gravity waves and the tensor perturbations of the SU(2) gauge field which sources the gravity waves at the linear level. Interestingly enough, we find that the gravity waves are adiabatic and Maldacena's consistency relation including a long wavelength gravity wave holds in this setup. However, since it is partially polarized, there is a difference between the (n+1)-point functions with different helicity states proportional to the ratio of the gauge field density to the total density. These chiral n-point functions are the imprints of the SU(2) gauge field on the primordial cosmological perturbations and a robust observational feature of their contribution to the physics of inflation.
H. Bahtiyar🇹🇷 · K. U. Can🇯🇵 · G. Erkol🇹🇷 · M. Oka🇯🇵 · T. T. Takahashi🇯🇵
We evaluate the electromagnetic transition on 2+1 flavor lattices corresponding to a pion mass of MeV. We extract the magnetic Sachs and Pauli form factors which give the - transition magnetic moment and the decay rates of baryons. We did not find a signal for the magnetic form factor of the neutral transition , which is suppressed by the U-spin flavor symmetry. As a byproduct, we extract the magnetic form factors and the magnetic moments of and baryons, which give an insight to the dynamics of , and quarks having masses at different scales.
Caio A. G. Prado🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Jorge Noronha🇧🇷 · Alexandre A. P. Suaide🇧🇷 · Marcelo G. Munhoz🇧🇷 · Mauro R. Cosentino🇧🇷
Event-by-event viscous hydrodynamics is combined with heavy quark energy loss models to compute heavy flavor flow cumulants , , and as well as the nuclear modification factors of and mesons in PbPb collisions at 2.76 TeV. Our results indicate that bottom quarks can flow as much as charm quarks in the range 8--30 GeV.
Benedict Aaronson🇬🇧 · Steven Abel🇬🇧 · Eirini Mavroudi🇬🇧
The interpolation from supersymmetric to non-supersymmetric heterotic theories is studied, via the Scherk-Schwarz compactification of supersymmetric 6D theories to 4D. A general modular-invariant Scherk-Schwarz deformation is deduced from the properties of the 6D theories at the endpoints, which significantly extends previously known examples. This wider class of non-supersymmetric 4D theories opens up new possibilities for model building. The full one-loop cosmological constant of such theories is studied as a function of compactification radius for a number of cases, and the following interpolating configurations are found: two supersymmetric 6D theories related by a T-duality transformation, with intermediate 4D maximum or minimum at the string scale; a non-supersymmetric 6D theory interpolating to a supersymmetric 6D theory, with the 4D theory possibly having an AdS minimum; a "metastable" non-supersymmetric 6D theory interpolating via a 4D theory to a supersymmetric 6D theory.
Michael Dine🇺🇸 · Patrick Draper🇺🇸 · Laurel Stephenson-Haskins🇺🇸 · Di Xu🇺🇸
We study the large dependence and the potential in supersymmetric QCD with small soft SUSY-breaking terms. Known exact results in SUSY QCD are found to reflect a variety of expectations from large perturbation theory, including the presence of branches and the behavior of theories with matter (both with and ). However, there are also striking departures from ordinary QCD and the conventional large description: instanton effects, when under control, are not exponentially suppressed at large , and branched structure in supersymmetric QCD is always associated with approximate discrete symmetries. We suggest that these differences motivate further study of large QCD on the lattice.
Maxim Dvornikov (1 and 2)🇷🇺 · Victor B. Semikoz (1) ((1) IZMIRAN, (2) Tomsk State University)🇷🇺
We study the magnetohydrodynamics of relativistic plasmas accounting for the chiral magnetic effect (CME). To take into account the evolution of the plasma velocity, obeying the Navier-Stokes equation, we approximate it by the Lorentz force accompanied by the phenomenological drag time parameter. On the basis of this ansatz, we obtain the contributions of both the turbulence effects, resulting from the dynamo term, and the magnetic field instability, caused by the CME, to the evolution of the magnetic field governed by the modified Faraday equation. In this way, we explore the evolution of the magnetic field energy and the magnetic helicity density spectra in the early Universe plasma. We find that the right-left electron asymmetry is enhanced by the turbulent plasma motion in a strong seed magnetic field compared to the pure the CME case studied earlier for the hot Universe plasma in the same broken phase.
We propose a gauge-invariant description for the Higgs mechanism by which a gauge boson acquires the mass. We do not need to assume spontaneous breakdown of gauge symmetry signaled by a non-vanishing vacuum expectation value of the scalar field. In fact, we give a manifestly gauge-invariant description of the Higgs mechanism in the operator level, which does not rely on spontaneous symmetry breaking. For concreteness, we discuss the gauge-Higgs models with and gauge groups explicitly. This enables us to discuss the confinement-Higgs complementarity from a new perspective.
S. A. Alavi🇮🇷 · N. Rezaei🇮🇷
We derive the relativistic Hamiltonian of hydrogen atom in dynamical noncommutative spaces (DNCS or {\tau}-space). Using this Hamiltonian we calculate the energy shift of the ground state and as well the [2P]_(1/2), [2S]_(1/2) levels. In all cases the energy shift depend on the dynamical noncommutative parameter {\tau}. Using the accuracy of the energy measurement we obtain an upper bound for {\tau}. We also study the lamb shift in DNCS. Both the levels [2P]_(1/2) and [2S]_(1/2) receive corrections due to dynamical noncommutativity of space which is in contrast to the non-dynamical noncommutative spaces (NDNCS or {\theta}-space) in which the level [2S]_(1/2) receives no correction.
We study the massless limit in synchrotron radiation and one-photon pair creation in magnetic field. In this limit Schwinger critical field tends to zero, so two characteristic quantum parameters are infinite, and the standard approximations used in analytical calculations fail. Applying Schwinger's proper time methods we derive simple expressions for synchrotron radiation spectra emitted by massless charges of spins and the pair creation probability distribution in the quasiclassical (high Landau levels) regime exhibiting simple scaling properties and possessing universal spectral shapes.
A. Deur🇺🇸
We report on the low and moderate Q^2 nucleon spin structure measurements done at Jefferson Lab, examining specifically the inclusive program. We discuss what the data teach us about quark confinement and the emergence of the effective hadronic degrees of freedom from the fundamental partonic ones. We show how this experimental program has reached its goal by providing a precise mapping at low, intermediate and moderately high Q^2 which has followed in many advances, e.g., with Chiral Perturbation Theory. Another example of a recent advance imputable to the JLab spin data is the improved understanding of \alpha_s at low energy, which allowed Light-Front Holographic QCD, an approximation to non-perturbative QCD, to derive the hadron spectrum from \Lambda_s.
We review lattice calculations of the elementary Greens functions of QCD with a special emphasis on the Landau gauge. These lattice results have been of interest to continuum approaches to QCD over the past 20 years. They are used as reference for Dyson-Schwinger- and functional renormalization group equation calculations as well as for hadronic bound-state equations. The lattice provides low-energy data for propagators and three-point vertices in Landau gauge at zero and finite temperature even including dynamical fermions. We summarize Michael Müller-Preußker's important contributions to this field and put them into the perspective of his other research interests.
Mehmet Koca · Ramazan Koc🇹🇷 · Nazife Ozdes Koca🇴🇲
We analyze the group structures of two groups of order 1344 which are respectively non-split and split extensions of the elementary Abelian group of order 8 by its automorphism group PSL_2(7).They share the same character table. The group 2^3.PSL_2(7) is a finite subgroup of the Lie Group G_2 preserving the set of octonions \pm e_i , (i=1,2,...,7) representing a 7-dimensional octahedron.Its three maximal subgroups 2^3:7:3, 2^3.S_4 and 4.S_4:2 correspond to the finite subgroups of the Lie groups G_2, SO(4) and SU(3) respectively. The group 2^3:PSL_2(7) representing the split extension possesses five maximal subgroups 2^3:7:3, 2^3:S_4, 4:S_4:2 and two non-conjugate Klein's group PSL_2(7).The character tables of the groups and their maximal subgroups, tensor products and decompositions of the irreducible representations under the relevant maximal subgroups are identified. Possible implications in physics are discussed.
Edwin Lizarazo🇬🇧 · Oliver Witzel🇬🇧
-physics is one of the most promising windows to find new physics in the flavor sector. One key ingredient to these searches are precise theoretical predictions derived from the Standard Model. Focusing at the nonperturbative QCD contributions, we carry out lattice QCD simulations in order to calculate -meson decay constants and semi-leptonic form factors. Combined with experimental measurements our results enable us to determine CKM matrix elements. Here we present and meson decay constants as well as semi-leptonic form factors including rare decays, CKM or GIM suppressed in the Standard Model. Our results are based on the set of 2+1 flavor domain-wall Iwasaki gauge field configurations generated by the RBC-UKQCD collaboration. Heavy -quarks are simulated using the relativistic heavy quark action.
Andreas Zacchi🇩🇪 · Laura Tolos🇩🇪 · Jürgen Schaffner-Bielich🇩🇪
We present new stable solutions of the Tolman Oppenheimer Volkoff equations for quark stars using a quark matter equation of state based on the SU(3) Quark-Meson model that exhibits the onset of the chiral phase transition. These new solutions appear as two stable branches in the mass-radius relation allowing for so called twin stars, i.e. two stable quark star solutions with the same mass, but distinctly different radii. We find solutions which are compatible with causality, the stability conditions of dense matter, the astrophysical constraints of the rotation of the millisecond pulsar PSR J1748-2446ad and the 2 pulsar mass constraint.
David Dudal🇧🇪 · Subhash Mahapatra🇧🇪
We consider the soft wall model for a heuristic holographical modelling of a confining gauge theory and discuss how the introduction of a (constant) magnetic field influences the (de)confinement phase structure. We use the entanglement entropy as a diagnostic tool in terms of the length of an entangling strip geometry. Due to the anisotropy introduced by the magnetic field, we find that the results depend on the orientation of the strip relative to the field. This allows to identify a richer, anisotropic, interplay between confinement and a magnetic field than possibly can be extracted from a more standard order parameter as, for example, the Polyakov loop expectation value.
Claudio Bonati🇮🇹 · Massimo D'Elia🇮🇹 · Marco Mariti🇮🇹 · Guido Martinelli🇮🇹 · Michele Mesiti🇮🇹 · Francesco Negro🇮🇹 · Francesco Sanfilippo🇬🇧 · Giovanni Villadoro🇮🇹
The properties of the QCD axion are strictly related to the dependence of strong interactions on the topological parameter theta. We present a determination of the topological properties of QCD for temperatures up to around 600 MeV, obtained by lattice QCD simulations with 2+1 flavors and physical quark masses. Numerical results for the topological susceptibility, when compared to instanton gas computations, differ both in size and in the temperature dependence. We discuss the implications of such findings for axion phenomenology, also in comparison to similar studies in the literature, and the prospects for future investigations.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.