Thu·Jan 25, 2018Thursday·January 25, 2018

1. 01*

   Parametrized Equation of State for QCD from 3D Ising Model

   Paolo Parotto🇺🇸

   The only first principle knowledge of the QCD equation of state at finite baryonic density is given from Lattice QCD as a Taylor expansion around ${\mu }_B=0$. The coefficients of such an expansion are currently available up to order $\mathcal{O}({\mu }_B^6)$. The expected critical behavior of QCD is in the same static universality class as the 3D Ising model. By means of a suitable parametrization for the scaling equation of state of 3D Ising and a parametrized map to connect to QCD, we present an equation of state matching first principle Lattice QCD calculations, which spans the values of baryonic densities explored in the BES-II program, and includes the correct scaling behavior in the proximity of the critical point. This EoS can serve as an important ingredient for the fluid dynamical simulations of heavy ion collisions at BES energies needed as a basis for the calculation of observables. Future comparisons between such calculations and BES-II data can constrain the parameters in the EoS -- including the parameters that describe the location of the critical point. This contribution reports on work done within the Fluctuations/Equation of State working group of the BEST Collaboration.

   hep-phnucl-thPoS(2018)·9 citations
2. 02*

   QED Plasma at High Temperature

   Samina S Masood🇺🇸

   We demonstrate that the early universe behaved as a relativistic QED (Quantum Electrodynamics) plasma around the nucleosynthesis time while the temperature of the universe was below the neutrino decoupling temperature in the early universe. QED coupling constant becomes a temperature dependent parameter due to the radiative corrections to vacuum polarization in the early universe at nucleosynthesis temperature. Renormalization scheme of QED is used to calculate the effective parameters of relativistic plasma in the early universe. Renormalization constants of QED serve as effective parameters of the theory and are used to determine the behavior of matter. We explicitly compute the parameters of QED plasma such as Debye length and the plasma frequency as a function of temperature. Light is slowed down and trapped due to bending in such a medium and the frequency of electromagnetic radiation becomes a function of temperature as well.

   hep-phastro-ph.HE0 citations
3. 03*

   Gauge structure of Yang-Mills theories with extra dimensions

   J. A. Ahuatzi-Avendaño🇲🇽 · A. J. Correa-León🇲🇽 · M. Huerta-Leal🇲🇽 · H. Novales-Sánchez🇲🇽 · A. Sierra-Martínez🇲🇽 · J. J. Toscano🇲🇽

   An effective Lagrangian for Yang-Mills theories with $n$ extra dimensions is constructed. We start from a field theory governed by the extra-dimensional Poincaré group $ISO(1,3+n)$ and the extended gauge group $SU(N,M^{4+n})$, characterized by an energy scale $\Lambda$ and assumed to be valid at energies far below this scale. Assuming that the size of the extra dimensions is much larger than the distance scale at which this theory is valid, an effective theory with symmetry groups $ISO(1,3)$ and $SU(N,M^4)$ is constructed. Such theories are connected by a canonical transformation that hides $ISO(1,3+n)\otimes SU(N,M^{4+n})$ into $ISO(1,3)\otimes SU(N,M^4)$, and endows the KK gauge fields with mass. Using a set of orthogonal functions $\{f^{(\underline{0})},f^{(\underline{m})}(\bar{x})\}$, generated by the Casimir invariant ${\bar{P}}^2$ associated with the translations subgroup $T(n)\subset ISO(n)$, the degrees of freedom of $ISO(1,3+n)\otimes SU(N,M^{4+n})$ are expanded via a general Fourier series, whose coefficients are the degrees of freedom of $ISO(1,3)\otimes SU(N,M^4)$. These functions, corresponding to the projection on the coordinates basis $\{|\bar{x}⟩\}$ of the discrete basis $\{|0⟩,|p^{(\underline{m})}⟩\}$ generated by ${\bar{P}}^2$, are central in defining the effective theory. Components along the base state $f^{(\underline{0})}=⟨\bar{x}|0⟩$, identified as the standard Yang-Mills fields, do not receive mass at the compactification scale; components along excited states $f^{(\underline{m})}=⟨\bar{x}|p^{(\underline{m})}⟩$, corresponding to KK excitations, receive mass at this scale. Associated with any direction $|p^{(\underline{m})}\ne 0⟩$ there are a massive gauge field and a pseudo-Goldstone boson. Resemblances of this mass-generating mechanism with the Brout-Englert-Higgs mechanism are stressed.

   hep-phhep-th1 citation
4. 04*

   Neutron Star Cooling via Axion Emission by Nucleon-Nucleon Axion Bremsstrahlung

   Avik Paul🇮🇳 · Debasish Majumdar🇮🇳 · Kamakshya Prasad Modak🇮🇳

   Neutron stars generally cools off by the emission of gamma rays and neutrinos. But axions can also be produced inside a neutron star by the process of nucleon-nucleon axion bremsstrahlung. The escape of these axions adds to the cooling process of neutron star. We explore the nature of cooling of neutron stars including the axion emission and compare our result with the scenario when the neutron star is cooled by only the emission of gamma rays and neutrinos. In our calculations we consider both the degenerate and non-degenerate limits for such axion energy loss rate and the resulting variation of luminosity with time and variation of surface temperature with time of the neutron star. In short the thermal evolution of a neutron star is studied with three neutron star masses (1.0, 1.4, 1.8 solar masses) and by including the effect of axion emission for different axion masses ($m_a=10^{-5}\mathrm{eV},10^{-3}\mathrm{eV},10^{-2}\mathrm{eV}$) and compared with the same when the axion emission is not considered. We compared theoretical cooling curve with the observational data of three pulsars PSR B056+14, Geminga and PSR B1055-52 and finally give an upper bound on axion mass limits $m_a\le 10^{-3}$ eV which implies that the axion decay constant $f_a\ge 0.6\times 10^{10}\mathrm{GeV}$.

   hep-phPramana(2019)·18 citations
5. 05*

   New Developments in WHIZARD Version 2.6

   W. Kilian🇩🇪 · S. Brass🇩🇪 · T. Ohl🇩🇪 · J. Reuter🇩🇪 · V. Rothe🇩🇪 · P. Stienemeier🇩🇪 · M. Utsch🇩🇪

   We describe recent additions to the WHIZARD 2 Monte-Carlo event generator which improve the physics description of lepton-collider event samples and speed up the calculation time required for cross sections and event generation.

   hep-phhep-ex14 citations
6. 06*

   Automatised ILC-Bounds on Dark Matter Models with CheckMATE

   Daniel Dercks🇩🇪 · Gudrid Moortgat-Pick🇩🇪

   The public collider phenomenology computing tool CheckMATE (Check Models at Terascale Energies) was originally designed to allow theorists to quickly test their favourite BSM models against various existing LHC analyses performed by ATLAS and CMS. It offers an automatised chain of Monte Carlo event generation, detector simulation, event analysis and statistical evaluation so that it can automatically determine whether a given parameter point of a BSM model is excluded or not. Currently, it contains more than 50 individual ATLAS or CMS analyses whose several hundred signal regions target various final states as they typically appear in theories beyond the Standard Model. In this study, we extend this functionality to allow sensitivity studies for the International Linear Collider. As an example, we implemente a dark matter monophoton search and use it to analyse three benchmark scenarios with different assumptions about the interaction between dark matter and Standard Model particles. We determine the ILC sensitivity expected for a $\sqrt{s}=$ 500 GeV, $L=500$ fb${}^{-1}$and compare the results for the cases of completely unpolarised beams and for individual lepton polarisation settings.

   hep-ph2 citations
7. 07*

   Polyakov loop fluctuations in the presence of external fields

   Pok Man Lo🇵🇱 · Michał Szymański🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

   We study the implications of the spontaneous and explicit Z(3) center symmetry breaking for the Polyakov loop susceptibilities. To this end, ratios of the susceptibilities of the real and imaginary parts, as well as of the modulus of the Polyakov loop are computed within an effective model using a color group integration scheme. We show that the essential features of the lattice QCD results of these ratios can be successfully captured by the effective approach. Furthermore we discuss a novel scaling relation in one of these ratios involving the explicit breaking field, volume, and temperature.

   hep-phhep-latPRD(2018)·6 citations
8. 08*

   The dimensionally reduced description of the high energy scattering and the effective action for the reggeized gluons

   S.Bondarenko🇮🇱 · M.A.Zubkov🇮🇱

   We discuss the high energy scattering of hadrons with the multi - Regge kinematics. The effective $2D$ model for the interaction between the produced hard gluons appears as a result of the dimensional reduction, which is similar to the dimensional reduction $3+1$ D $\to 3$ D of the high temperature gauge theory. It is demonstrated that being supplemented by the exchange by virtual $3+1$ D gluons this $2D$ model gives rise to the hermitian version of the effective action of Lipatov for the interaction between the ordinary and the reggeized gluons.

   hep-phEPJC(2018)·18 citations
9. 09*

   Studying G-axion Inflation model in light of PLANCK

   Debaprasad Maity🇮🇳 · Pankaj Saha🇮🇳

   With the Planck 2015 result, most of the well known canonical large field inflation models turned out to be strongly disfavored. Axion inflation is one of such models which is becoming marginalized with the increasing precession of CMB data. In this paper, we have shown that with a simple Galileon type modification to the marginally favored axion model calling G-axion, we can turn them into one of the most favored models with its detectable prediction of $r$ and $n_s$ within its PLANCK $1\sigma$ range for a wide range of parameters. Interestingly it is this modification which plays the important role in turning the inflationary predictions to be independent of the explicit value of axion decay constant $f$. However, dynamics after the inflation turned out to have a non-trivial dependence on $f$. For each G-axion model there exists a critical value of $f_c$ such that for $f>f_c$ we have the oscillating phase after inflation and for $f<f_c$ we have non-oscillatory phase. Therefore, we obtained a range of sub-Planckian value of model parameters which give rise to consistent inflation. However for sub-Planckian axion decay constant the inflaton field configuration appeared to be singular after the end of inflation. To reheat the universe we, therefore, employ the instant preheating mechanism at the instant of first zero crossing of the inflaton. To our surprise, the instant preheating mechanism turned out to be inefficient as opposed to usual non-oscillatory quintessence model. For another class of G-axion model with super-Planckian axion decay constant, we performed in detail the reheating constraints analysis considering the latest PLANCK result.

   hep-phastro-ph.COJCAP(2018)·4 citations
10. 10*

    Exclusive top production at a Linear Collider at and off the threshold

    Jürgen Reuter🇩🇪 · Fabian Bach · Bijan Chokoufé Nejad🇩🇪 · Andre Hoang🇦🇹 · Wolfgang Kilian🇩🇪 · Jonas Lindert🇬🇧 · Stefano Pozzorini🇨🇭 · Maximilian Stahlhofen🇩🇪 · Thomas Teubner🇬🇧 · Christian Weiss🇩🇪

    We review exclusive top pair production including decays at a future high-energy lepton collider, both in the threshold region and for higher energies. For the continuum process, we take complete QCD next-to-leading order matrix elements for the $2\to 6$ process with leptonic W decays into account. At threshold, we match the fixed-order relativistic QCD-NLO cross section to a nonrelativistic cross section with next-to-leading logarithmic (NLL) threshold resummation implemented via a form factor.

    hep-ph3 citations
11. 11*

    New experimental approaches in the search for axion-like particles

    Igor G. Irastorza🇪🇸 · Javier Redondo🇪🇸

    Axions and other very light axion-like particles appear in many extensions of the Standard Model, and are leading candidates to compose part or all of the missing matter of the Universe. They also appear in models of inflation, dark radiation, or even dark energy, and could solve some long-standing astrophysical anomalies. The physics case of these particles has been considerably developed in recent years, and there are now useful guidelines and powerful motivations to attempt experimental detection. Admittedly, the lack of positive signal of new physics at the high energy frontier, and in underground detectors searching for weakly interacting massive particles, is also contributing to the increase of the interest in axion searches. The experimental landscape is rapidly evolving, with many novel detection concepts and new experiments being proposed lately. An updated account of those initiatives is lacking in the literature. In this review we attempt to provide such a review. We will focus on the new experimental approaches and their complementarity, but will also review the most relevant recent results from the consolidated strategies and the prospects of new generation experiments under consideration in the field. We will also briefly review the latest developments of the theory, cosmology and astrophysics of axions and we will discuss the prospects to probe a large fraction of relevant parameter space in the coming decade.

    hep-phhep-exPPNP(2018)·1020 citations
12. 12*

    Running bumps from stealth bosons

    J. A. Aguilar-Saavedra🇪🇸

    For the "stealth bosons" $S$, light boosted particles with a decay $S\to AA\to q\bar{q}q\bar{q}$ into four quarks and reconstructed as a single fat jet, the groomed jet mass has a strong correlation with groomed jet substructure variables. Consequently, the jet mass distribution is strongly affected by the jet substructure selection cuts when applied on the groomed jet. We illustrate this fact by recasting a CMS search for low-mass dijet resonances and show a few representative examples. The mass distributions exhibit narrow and wide bumps at several locations in the 100 - 300 GeV range, between the masses of the daughter particles $A$ and the parent particle $S$, depending on the jet substructure selection. This striking observation introduces several caveats when interpreting and comparing experimental results, for the case of non-standard signatures. The possibility that a single boosted particle decaying hadronically produces multiple bumps, at quite different jet masses, and depending on the event selection, brings the game of anomaly chasing to the next level.

    hep-phhep-exEPJC(2018)·6 citations
13. 13*

    Three-loop massive form factors: complete light-fermion corrections for the vector current

    Roman N. Lee🇷🇺 · Alexander V. Smirnov🇷🇺 · Vladimir A. Smirnov🇷🇺 · Matthias Steinhauser🇩🇪

    We compute the three-loop QCD corrections to the massive quark-anti-quark-photon form factors $F_1$ and $F_2$ involving a closed loop of massless fermions. This subset is gauge invariant and contains both planar and non-planar contributions. We perform the reduction using FIRE and compute the master integrals with the help of differential equations. Our analytic results can be expressed in terms of Goncharov polylogarithms. We provide analytic results for all master integrals which are not present in the large-$N_c$ calculation considered in Refs. [1,2].

    hep-phJHEP(2018)·36 citations
14. 14*

    Electromagnetic form factors of ${\Lambda }_c$ in the Bethe-Salpeter equation approach

    Liang-Liang Liu🇨🇳 · Chao Wang🇨🇳 · Xin-Heng Guo🇨🇳

    We study the electromagnetic form factors (EMFFs) of ${\Lambda }_c$ and the quark and diquark current contributes to the EMFFs of ${\Lambda }_c$ in the space-like (SL) region in the Bethe-Salpeter equation approach. In this picture, the heavy baryon ${\Lambda }_c$ is regarded as composed of a heavy quark and a scalar diquark. We find that for different values of parameters the quark and diquark current contribute to the EMFFs of ${\Lambda }_c$ is very different, but the total contribute to the EMFFs of ${\Lambda }_c$ is similarly. The EMFFs of ${\Lambda }_c$ are similar to those of other baryons (proton, ${\Xi }^{-}$, ${\Sigma }^{+}$) with a peak at $\omega =1$ ($\omega =v^{\prime }\cdot v$ is the velocity transfer between the initial state (with velocity $v$) and the final state (with velocity $v^{\prime }$) of ${\Lambda }_c$).

    hep-phCPC(2018)·5 citations
15. 15*

    Analysis of the triply-charmed pentaquark states with QCD sum rules

    Zhi-Gang Wang🇨🇳

    In this article, we construct the scalar-diquark-scalar-diquark-antiquark type current to study the ground state triply charmed pentaquark states with the QCD sum rules. We separate the contributions of the negative-parity and positive parity triply charmed pentaquark states explicitly, and take the energy scale formula $\mu =\sqrt{M_P^2-(3{\mathbb{M}}_c{)}^2}$ to determine the optimal energy scales of the QCD spectral densities. The predicted pentaquark masses can be confronted to the experimental data in the future.

    hep-phEPJC(2018)·12 citations
16. 16*

    Matter-neutrino resonance in a multi-angle neutrino bulb model

    A. Vlasenko🇺🇸 · G. C. McLaughlin🇺🇸

    Simulations of neutrino flavor evolution in compact merger environments have shown that neutrino flavor, and hence nucleosynthesis, can be strongly affected by the presence of matter-neutrino resonances (MNRs), where there is a cancelation between the matter and the neutrino potential. Simulations performed thus far follow flavor evolution along a single neutrino trajectory, but self-consistency requires all trajectories to be treated simultaneously, and it has not been known whether MNR phenomena would still occur in multi-angle models. In this paper, we present the first fully multi-angle calculations of MNR. We find that familiar MNR phenomena, where neutrinos transform to a greater extent than anti-neutrinos and a feedback mechanism maintains the cancellation between the matter and neutrino potential, still occurs for a subset of angular bins, although the flavor transformation is not as efficient as in the single-angle case. In addition, we find other types of flavor transformation that are not seen in single-angle simulations. These flavor transformation phenomena appear to be robust and are present for a wide range of model parameters, as long as an MNR is present. Although computational constraints currently limit us to models with spherical symmetry, our results suggest that the presence of an MNR generally leads to large-scale neutrino flavor evolution in multi-angle systems.

    ↳ astro-ph.HEhep-phnucl-thPRD(2018)·31 citations
17. 17*

    Higgs boson results on couplings to fermions, CP parameters and perspectives for HL-LHC (ATLAS AND CMS)

    Johannes Brandstetter (on behalf of the ATLAS and CMS Collaborations)🇦🇹

    This report summarizes latest ATLAS and CMS results on Higgs boson couplings to fermions.~Presented topics include decays into final states of pairs of tau leptons and pairs of bottom quarks as well as results on the ttH production mode.~Results are complemented by tests of the CP invariance and searches for lepton flavor violating decays.~Finally, prospects of future Higgs boson analyses within the scope of the High Luminosity LHC program are discussed.~The presented results mostly use LHC 2016 data collected at a center-of-mass energy of $\sqrt{\mathrm{s}}=13$TeV corresponding to an integrated luminosity of about 36$\mathrm{f}{\mathrm{b}}^{-1}$.

    ↳ hep-exhep-ph7 citations
18. 18*

    Removal Energies and Final State Interaction in Lepton Nucleus Scattering

    Arie Bodek🇺🇸 · Tejin Cai🇺🇸

    We investigate the binding energy parameters that should be used in modeling electron and neutrino scattering from nucleons bound in a nucleus within the framework of the impulse approximation. We discuss the relation between binding energy, missing energy, removal energy ($ϵ$), spectral functions and shell model energy levels and extract updated removal energy parameters from ee${}^{\prime }$p spectral function data. We address the difference in parameters for scattering from bound protons and neutrons. We also use inclusive e-A data to extract an empirical parameter $U_{FSI}(({\vec{q}}_3+\vec{k}{)}^2)$ to account for the interaction of final state nucleons (FSI) with the optical potential of the nucleus. Similarly we use $V_{eff}$ to account for the Coulomb potential of the nucleus. With three parameters $ϵ$, $U_{FSI}(({\vec{q}}_3+\vec{k}{)}^2)$ and $V_{eff}$ we can describe the energy of final state electrons for all available electron QE scattering data. The use of the updated parameters in neutrino Monte Carlo generators reduces the systematic uncertainty in the combined removal energy (with FSI corrections) from $\pm$ 20 MeV to $\pm$ 5 MeV.

    ↳ nucl-thhep-exhep-phEPJC(2019)·69 citations
19. 19*

    Regularity of high energy photon events from gamma ray bursts

    Haowei Xu🇨🇳 · Bo-Qiang Ma🇨🇳

    The effect of Quantum Gravity (QG) may bring a tiny light speed variation as $v(E)=c(1-E/E_{\mathrm{LV}})$, where $E$ is the photon energy and $E_{\mathrm{LV}}$ is a Lorentz violation scale. A remarkable regularity was suggested in previous studies to look for the light speed variation from high energy photon events of Gamma Ray Bursts (GRBs). We provide a general analysis on the data of 25 bright GRBs observed by the Fermi Gamma-ray Space Telescope (FGST). Such method allows a completed scan over all possibilities in a more clean and impartial way without any bias compared to previous intuitive analysis. The results show that with the increase in the intrinsic energies of photons, such regularity truly emerges and gradually becomes significant. For photons with intrinsic energies higher than 40~GeV, the regularity exists at a significance of 3-5~$\sigma$ with $E_{\mathrm{LV}}=3.6\times 10^{17}\mathrm{GeV}$ determined by the GRB data.

    ↳ gr-qcastro-ph.HEhep-phJCAP(2018)·49 citations
20. 20*

    Current and future constraints on extended Bekenstein-type models for a varying fine-structure constant

    C. S. Alves🇵🇹 · A. C. O. Leite🇵🇹 · C. J. A. P. Martins🇵🇹 · T. A. Silva🇵🇹 · S. A. Berge🇸🇪 · B. S. A. Silva🇵🇹

    There is a growing interest in astrophysical tests of the stability of dimensionless fundamental couplings, such as the fine-structure constant $\alpha$, as an optimal probe of new physics. The imminent arrival of the ESPRESSO spectrograph will soon enable significant gains in the precision and accuracy of these tests and widen the range of theoretical models that can be tightly constrained. Here we illustrate this by studying proposed extensions of the Bekenstein-type models for the evolution of $\alpha$ that allow different couplings of the scalar field to both dark matter and dark energy. We use a combination of current astrophysical and local laboratory data (from tests with atomic clocks) to show that these couplings are constrained to parts per million level, with the constraints being dominated by the atomic clocks. We also quantify the expected improvements from ESPRESSO and other future spectrographs, and briefly discuss possible observational strategies, showing that these facilities can improve current constraints by more than an order of magnitude.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2018)·19 citations
21. 21*

    The Search for Dark Matter

    Laura Baudis🇨🇭

    The dark matter problem is almost a century old. Since the 1930s evidence has been growing that our cosmos is dominated by a new form of non-baryonic matter, that holds galaxies and clusters together and influences cosmic structures up to the largest observed scales. At the microscopic level, we still do not know the composition of this dark, or invisible matter, which does not interact directly with light. The simplest assumption is that it is made of new particles that interact with gravity and at most weakly with known elementary particles. I will discuss searches for such new particles, both space- and Earth-bound including those placed in deep underground laboratories. While a dark matter particle hasn't been yet identified, even after decades of concerted efforts, new technological developments and experiments have reached sensitivities where a discovery might be imminent, albeit certainly not guaranteed.

    ↳ astro-ph.COhep-phEur.Rev.(2017)·43 citations
22. 22*

    Dynamics of vortices in chiral media: the chiral propulsion effect

    Yuji Hirono🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Andrey V. Sadofyev🇺🇸

    We study the motion of vortex filaments in chiral media, and find a semi-classical analog of the anomaly-induced chiral magnetic effect. The helical solitonic excitations on vortices in a parity-breaking medium are found to carry an additional energy flow along the vortex in the direction dictated by the sign of chirality imbalance; we call this new transport phenomenon the Chiral Propulsion Effect (CPE). The dynamics of the filament is described by a modified version of the localized induction equation in the parity-breaking background. We analyze the linear stability of simple vortex configurations, and study the effects of chiral media on the excitation spectrum and the growth rate of the unstable modes. It is also shown that, if the equation of motion of the filament is symmetric under the simultaneous reversal of parity and time, the resulting planar solution cannot transport energy.

    ↳ hep-thcond-mat.str-elhep-phnucl-thPRL(2018)·4 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.