HEP Phenomenology·hep-ph

Wed·Dec 13, 2017Wednesday·December 13, 2017

19 papers—11 primary·8 cross-listed·reconstructed*

01*
Effective Majorana mass matrix from tau and pseudoscalar meson lepton number violating decays
Asmaa Abada🇫🇷 · Valentina De Romeri🇪🇸 · Michele Lucente🇧🇪 · Ana M. Teixeira🇫🇷 · Takashi Toma🇩🇪
An observation of any lepton number violating process will undoubtedly point towards the existence of new physics and indirectly to the clear Majorana nature of the exchanged fermion. In this work, we explore the potential of a minimal extension of the Standard Model via heavy sterile fermions with masses in the $[0.1 - 10]$ GeV range concerning an extensive array of "neutrinoless" meson and tau decay processes. We assume that the Majorana neutrinos are produced on-shell, and focus on three-body decays. We conduct an update on the bounds on the active-sterile mixing elements, $∣ U_{ℓ_{α} 4} U_{ℓ_{β} 4} ∣$ , taking into account the most recent experimental bounds (and constraints) and new theoretical inputs, as well as the effects of a finite detector, imposing that the heavy neutrino decay within the detector. This allows to establish up-to-date comprehensive constraints on the sterile fermion parameter space. Our results suggest that the branching fractions of several decays are close to current sensitivities (likely within reach of future facilities), some being already in conflict with current data (as is the case of $K^{+} \to ℓ_{α}^{+} ℓ_{β}^{+} π^{-}$ , and $τ^{-} \to μ^{+} π^{-} π^{-}$ ). We use these processes to extract constraints on all entries of an enlarged definition of a $3 \times 3$ "effective" Majorana neutrino mass matrix $m_{ν}^{α β}$ .
hep-phhep-exJHEP(2018)·89 citations
02*
Strangeness Production in low energy Heavy Ion Collisions via Hagedorn Resonances
K. Gallmeister🇩🇪 · M. Beitel🇩🇪 · C. Greiner🇩🇪
A novel, unorthodox picture of the dynamics of heavy ion collisions is developed using the concept of Hagedorn states. A prescription of the bootstrap of Hagedorn states respecting the conserved quantum numbers baryon number B, strangeness S, isospin I is implememted into the GiBUU transport model. Using a strangeness saturation suppression factor suitable for nucleon-nucleon-collisions, recent experimental data for the strangeness production by the HADES collaboration in Au+Au and Ar+KCl is reasonable well described. The experimental observed exponential slopes of the energy distributions are nicely reproduced. Thus, a dynamical model using Hagedorn resonance states, supplemented by a strangeness saturation suppression factor, is able to explain essential features (multiplicities, exponential slope) of experimental data for strangeness production in nucleus-nucleus collisions close to threshold.
hep-phhep-exnucl-thPRC(2018)·13 citations
03*
World-line formulation of chiral kinetic theory in topological background gauge fields
Niklas Mueller🇺🇸 · Raju Venugopalan🇺🇸
In heavy-ion collisions, an interesting question of phenomenological relevance is how the chiral imbalance generated at early times persists through a fluctuating background of sphalerons in addition to other "non-anomalous" interactions with the QGP. To address this question, we construct a relativistic chiral kinetic theory using the world-line formulation of quantum field theory. We outline how Berry's phase arises in this framework, and how its effects can be clearly distinguished from those arising from the chiral anomaly. We further outline how this framework can be matched to classical statistical simulations at early times and to anomalous chiral hydrodynamics at late times.
hep-phhep-thnucl-thPoS(2018)·4 citations
04*
Interference Effects in a Very Precise Measurement of the Muon Charge Asymmetry at FCC-ee
S. Jadach🇵🇱 · S. Yost🇺🇸
At the future high luminosity electron-positron collider FCC-ee proposed for CERN, the precise measurement of the charge asymmetry in $e^{+} e^{-} \to μ^{+} μ^{-}$ near the Z resonance is of special interest. In particular, such a measurement at $M_{Z} \pm 3.5$ GeV may provide a very precise measurement of the electromagnetic coupling at the scale $\sim M_{Z}$ , a fundamental constant of the Standard Model. However, this charge asymmetry is plagued by a large trivial contribution from the interference of photon emission from initial state electrons and final state muons. We address the question whether this interference can be reliably calculated and subtracted with the help of a resummed QED calculation.
hep-phActa Phys.Polon.B(2017)·0 citations
05*
Soft Particle Production in Cosmic Ray Showers
Jan Ebr🇨🇿
Indications of a discrepancy between simulations and data on the number of muons in cosmic ray showers exist over a large span of energies. We focus on the excess of multi-muon bundles observed by the DELPHI detector at LEP and on the excess in the muon number in general reported by the Pierre Auger Observatory. Even though the primary CR energies relevant for these experiments differ by orders of magnitude, we can find a single mechanism which can simultaneously increase predicted muon counts for both, while not violating constraints from accelerators or from the longitudinal shower development as observed by the Pierre Auger Observatory. We present a brief motivation and describe a practical implementation of such a model, based on the addition of soft particles to interactions above a chosen energy threshold. Results of an extensive set of simulations show the behavior of this model in various parts of a simplified parameter space.
hep-phhep-ex0 citations
06*
Production of a tensor glueball in the reaction $γ γ \to G_{2} π^{0}$ at large momentum transfer
N. Kivel🇩🇪 · M. Vanderhaeghen🇩🇪
We study the production of a tensor glueball in the reaction $γ γ \to G_{2} π^{0}$ . We compute the cross section at higher momentum transfer using the collinear factorisation approach. We find that for a value of the tensor gluon coupling of $f_{g}^{T} \sim 100$ ~MeV, the cross section can be measured in the near future by the Belle~II experiment.
hep-phPLB(2018)·4 citations
07*
Lepton mixing and the charged-lepton mass ratios
D. Jurciukonis🇱🇹 · L. Lavoura🇵🇹
We construct a class of renormalizable models for lepton mixing that generate predictions given in terms of the charged-lepton mass ratios. We show that one of those models leads, when one takes into account the known experimental values, to almost maximal CP-breaking phases and to almost maximal neutrinoless double-beta decay. We study in detail the scalar potential of the models, especially the bounds imposed by unitarity on the values of the quartic couplings.
hep-phJHEP(2018)·1 citation
08*
Analytic structure of nonhydrodynamic modes in kinetic theory
Aleksi Kurkela🇨🇭 · Urs Achim Wiedemann🇨🇭
How physical systems approach hydrodynamic behavior is governed by the decay of nonhydrodynamic modes. Here, we start from a relativistic kinetic theory that encodes relaxation mechanisms governed by different timescales thus sharing essential features of generic weakly coupled nonequilib- rium systems. By analytically solving for the retarded correlation functions, we clarify how branch cuts arise generically from noncollective particle excitations, how they interface with poles arising from collective hydrodynamic excitations, and to what extent the appearance of poles remains at best an ambiguous signature for the onset of fluid dynamic behavior. We observe that processes that are slower than the hydrodynamic relaxation timescale can make a system that has already reached fluid dynamic behavior to fall out of hydrodynamics at late times. In addition, the analytical control over this model allows us to explicitly demonstrate how the hydrodynamic gradient expansion of the correlation functions can be Borel resummed such that the full nonperturbative information is recovered using perturbative input only.
hep-phEPJC(2019)·95 citations
09*
Production of a light top-squark pair in association with a light non-standard Higgs boson within the NMSSM at the 13 TeV LHC and a 33 TeV proton collider
Siba Prasad Das🇨🇴 · Jorge Fraga🇨🇴 · Carlos Avila🇨🇴
We study the potential of the LHC accelerator, and a future 33 TeV proton collider, to observe the production of a light top squark pair in association with the lightest Higgs boson ( $t ~_{1} t ~_{1} h_{1}$ ), as predicted by the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We scan randomly about ten million points of the NMSSM parameter space, allowing all possible decays of the lightest top squark and lightest Higgs boson, with no assumptions about their decay rates, except for known physical constraints such as perturbative bounds, Dark matter relic density consistent with recent Planck experiment measurements, Higgs mass bounds on the next to lightest Higgs boson, $h_{2}$ , assuming it is consistent with LHC measurements for the Standard Model Higgs boson, LEP bounds for the chargino mass and Z invisible width, experimental bounds on B meson rare decays and some LHC experimental bounds on SUSY particle spectra different to the particles involved in our study. We find that for low mass top-squark, the dominating decay mode is $t ~_{1} \to b χ ~_{1}^{\pm}$ with $χ ~_{1}^{\pm} \to W^{\pm} χ ~_{1}^{0}$ . We use three bench mark points with the highest cross sections, which naturally fall within the compressed spectra of the top squark, and make a phenomenological analysis to determine the optimal event selection that maximizes the signal significance over backgrounds. We focus on the leptonic decays of both $W$ 's and the decay of lightest Higgs boson into b-quarks ( $h_{1} \to b b ˉ$ ). Our results show that the high luminosity LHC will have limitations to observe the studied signal and only a proton collider with higher energy will be able to observe the SUSY scenario studied with more than three standard deviations over background.
hep-phhep-exInt.J.Mod.Phys.A(2019)·6 citations
10*
Anomalous dimension of subleading-power N-jet operators
Martin Beneke🇩🇪 · Mathias Garny🇩🇪 · Robert Szafron🇩🇪 · Jian Wang🇩🇪
We begin a systematic investigation of the anomalous dimension of subleading power N-jet operators in view of resummation of logarithmically enhanced terms in partonic cross sections beyond leading power. We provide an explicit result at the one-loop order for fermion-number two N-jet operators at the second order in the power expansion parameter of soft-collinear effective theory.
hep-phhep-thJHEP(2018)·117 citations
11*
All orders structure and efficient computation of linearly reducible elliptic Feynman integrals
Martijn Hidding🇮🇪 · Francesco Moriello🇨🇭
We define linearly reducible elliptic Feynman integrals, and we show that they can be algorithmically solved up to arbitrary order of the dimensional regulator in terms of a 1-dimensional integral over a polylogarithmic integrand, which we call the inner polylogarithmic part (IPP). The solution is obtained by direct integration of the Feynman parametric representation. When the IPP depends on one elliptic curve (and no other algebraic functions), this class of Feynman integrals can be algorithmically solved in terms of elliptic multiple polylogarithms (eMPLs) by using integration by parts identities. We then elaborate on the differential equations method. Specifically, we show that the IPP can be mapped to a generalized integral topology satisfying a set of differential equations in $ϵ$ -form. In the examples we consider the canonical differential equations can be directly solved in terms of eMPLs up to arbitrary order of the dimensional regulator. The remaining 1-dimensional integral may be performed to express such integrals completely in terms of eMPLs. We apply these methods to solve two- and three-points integrals in terms of eMPLs. We analytically continue these integrals to the physical region by using their 1-dimensional integral representation.
hep-phJHEP(2019)·77 citations
12*
Jet-medium interaction and the Gubser flow
Li Yan🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We study the effects of expansion and viscous corrections on the hydrodynamical medium response to a high energy jet parton. More specifically, using a semi-analytical Gubser solution to relativistic fluid dynamics, modifications to the formed Mach cone, diffusive wake, and the momentum flow of the medium response along and perpendicular to the jet particle, are analyzed mode-by-mode. This should provide intuition and guidance for analyses of the experimentally measured jet sub-structure in heavy-ion collisions.
↳ nucl-thhep-phnucl-exPoS(2018)·2 citations
13*
Nucleon and nuclear structure through dilepton production
I.V. Anikin · N. Batzell · M. Boer · R. Boussarie · V.M. Braun · S.J. Brodsky · A. Camsonne · W.C. Chang · L. Colaneri · S. Dobbs · A.V. Efremov · K. Gnanvo and 20 other authors
Transverse momentum distributions and generalized parton distributions provide a comprehensive framework for the three-dimensional imaging of the nucleon and the nucleus experimentally using deeply virtual semi-exclusive and exclusive processes. The advent of combined high luminosity facilities and large acceptance detector capabilities enables experimental investigation of the partonic structure of hadrons with time-like virtual probes, in complement to the rich on-going space-like virtual probe program. The merits and benefits of the dilepton production channel for nuclear structure studies are discussed within the context of the International Workshop on Nucleon and Nuclear Structure through Dilepton Production taking place at the European Center for Theoretical Studies in Nuclear Physics and Related Areas (ECT $^{⋆}$ ) of Trento. Particularly, the double deeply virtual Compton scattering, the time-like Compton scattering, the deeply virtual meson production, and the Drell-Yan processes are reviewed and a strategy for high impact experimental measurements is proposed.
↳ nucl-exhep-phActa Phys.Polon.B(2018)·31 citations
14*
Sp(4) gauge theory on the lattice: towards SU(4)/Sp(4) composite Higgs (and beyond)
Ed Bennett🇬🇧 · Deog Ki Hong🇰🇷 · Jong-Wan Lee🇰🇷 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Maurizio Piai🇬🇧 · Davide Vadacchino🇬🇧
The Sp(4) gauge theory with two Dirac fundamental flavours provides a candidate for the microscopic origin of composite-Higgs models based on the SU(4)/Sp(4) coset. We employ a combination of two different, complementary strategies for the numerical lattice calculations, based on the Hybrid Monte Carlo and on the Heat Bath algorithms. We perform pure Yang-Mills, quenched computations and exploratory studies with dynamical Wilson fermions. We present the first results in the literature for the spectrum of glueballs of the pure Sp(4) Yang-Mills theory, an EFT framework for the interpretation of the masses and decay constants of the lightest pion, vector and axial-vector mesons, and a preliminary calculation of the latter in the quenched approximation. We show the first numerical evidence of a bulk phase transition in the lattice theory with dynamical Wilson fermions, and perform the technical steps necessary to set up future investigations of the mesonic spectrum of the full theory.
↳ hep-lathep-phJHEP(2018)·126 citations
15*
Hybrid Higgs Inflation: The Use of Disformal Transformation
Seiga Sato🇯🇵 · Kei-ichi Maeda🇯🇵
We propose a hybrid type of the conventional Higgs inflation and new Higgs inflation models. We perform a disformal transformation into the Einstein frame and analyze the background dynamics and the cosmological perturbations in the truncated model, in which we ignore the higher-derivative terms of the Higgs field. From the observed power spectrum of the density perturbations, we obtain the constraint on the non-minimal coupling constant $ξ$ and the mass parameter $M$ in the derivative coupling. Although the primordial tilt $n_{s}$ in the hybrid model barely changes, the tensor-to-scalar ratio $r$ moves from the value in new Higgs inflationary model to that in the conventional Higgs inflationary model as $∣ ξ ∣$ increases. We confirm our results by numerical analysis by ADM formalism of the full theory in the Jordan frame.
↳ gr-qcastro-ph.COhep-phhep-thPRD(2018)·24 citations
16*
Model-Independent Predictions for Smooth Cosmic Acceleration Scenarios
V Miranda🇺🇸 · Cora Dvorkin🇺🇸
Through likelihood analyses of both current and future data that constrain both the expansion history of the universe and the clustering of matter fluctuations, we provide falsifiable predictions for three broad classes of models that explain the accelerated expansions of the universe: $Λ$ CDM, the quintessence scenario and a more general class of smooth dark energy models that can cross the phantom barrier $w (z) = - 1$ . Our predictions are model independent in the sense that we do not rely on a specific parametrization, but we instead use a principal component (PC) basis function constructed a priori from a noise model of supernovae and Cosmic Microwave Background observations. For the supernovae measurements, we consider two type of surveys: the current JLA and the upcoming WFIRST surveys. We show that WFIRST will be able to improve growth predictions in curved models significantly. The remaining degeneracy between spatial curvature and $w (z)$ could be overcome with improved measurements of $σ_{8} Ω_{m}^{1/2}$ , a combination that controls the amplitude of the growth of structure. We also point out that a PC-based Figure of Merit reveals that the usual two-parameter description of $w (z)$ does not exhaust the information that can be extracted from current data (JLA) or future data (WFIRST).
↳ astro-ph.COhep-phhep-thPRD(2018)·13 citations
17*
PArthENoPE reloaded
R. Consiglio🇮🇹 · P.F. de Salas🇪🇸 · G. Mangano🇮🇹 · G. Miele🇮🇹 · S. Pastor🇪🇸 · O. Pisanti🇮🇹
We describe the main features of a new and updated version of the program PArthENoPE, which computes the abundances of light elements produced during Big Bang Nucleosynthesis. As the previous first release in 2008, the new one, PArthENoPE 2.0, will be soon publicly available and distributed from the code site, http://parthenope.na.infn.it. Apart from minor changes, which will be also detailed, the main improvements are as follows. The powerful, but not freely accessible, NAG routines have been substituted by ODEPACK libraries, without any significant loss in precision. Moreover, we have developed a Graphical User Interface (GUI) which allows a friendly use of the code and a simpler implementation of running for grids of input parameters. Finally, we report the results of PArthENoPE 2.0 for a minimal BBN scenario with free radiation energy density.
↳ astro-ph.COhep-phComput.Phys.Commun.(2018)·171 citations
18*
Isotropic-Nematic Phase Transitions in Gravitational Systems II: Higher Order Multipoles
Ádám Takács🇭🇺 · Bence Kocsis
The gravitational interaction among bodies orbiting in a spherical potential leads to the rapid relaxation of the orbital planes' distribution, a process called vector resonant relaxation. We examine the statistical equilibrium of this process for a system of bodies with similar semimajor axes and eccentricities. We extend the previous model of Roupas et al. (2017) by accounting for the multipole moments beyond the quadrupole, which dominate the interaction for radially overlapping orbits. Nevertheless, we find no qualitative differences between the behavior of the system with respect to the model restricted to the quadrupole interaction. The equilibrium distribution resembles a counterrotating disk at low temperature and a spherical structure at high temperature. The system exhibits a first order phase transition between the disk and the spherical phase in the canonical ensemble if the total angular momentum is below a critical value. We find that the phase transition erases the high order multipoles, i.e. small-scale structure in angular momentum space, most efficiently. The system admits a maximum entropy and a maximum energy, which lead to the existence of negative temperature equilibria.
↳ astro-ph.GAcond-mat.stat-mechhep-phhep-thApJ(2018)·20 citations
19*
Light-meson masses in an unquenched quark model
Xiaoyun Chen🇨🇳 · Jialun Ping🇨🇳 · Craig D. Roberts🇺🇸 · Jorge Segovia🇪🇸
We perform a coupled-channels calculation of the masses of light mesons with the quantum numbers $I J^{P = -}$ , $(I, J) = 0, 1$ , by including $q q ˉ$ and $(q q ˉ)^{2}$ components in a nonrelativistic chiral quark model. The coupling between two- and four-quark configurations is realized through a $^{3} P_{0}$ quark-pair creation model. With the usual form of this operator, the mass shifts are large and negative, an outcome which raises serious issues of validity for the quenched quark model. Herein, therefore, we introduce some improvements of the $^{3} P_{0}$ operator in order to reduce the size of the mass shifts. By introducing two simple factors, physically well motivated, the coupling between $q q ˉ$ and $(q q ˉ)^{2}$ components is weakened, producing mass shifts that are around 10-20% of hadron bare masses.
↳ nucl-thhep-phnucl-exPRD(2018)·32 citations

* 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.