Wed·Jul 25, 2018Wednesday·July 25, 2018

1. 01*

   High Scale Electroweak Phase Transition: Baryogenesis & Symmetry Non-Restoration

   Iason Baldes🇩🇪 · Geraldine Servant🇩🇪

   We explore the possibility that the electroweak phase transition happens at a scale much higher than the electroweak scale today. In this context, high scale CP-violating sources for electroweak baryogenesis are not constrained by low-energy experiments. We propose a scenario of high-scale electroweak baryogenesis linked to flavour physics. This scenario allows for a period of enhanced Yukawa couplings during the evolution of the universe, which source time-dependent CP violation. The electroweak symmetry is never restored after the high-scale phase transition due to negative contributions to the Higgs thermal mass squared from a large number of additional electroweak-scale neutral scalars coupling to the Higgs. As a result, the washout of the baryon asymmetry is avoided.

   hep-phJHEP(2018)·122 citations
2. 02*

   Charged current quasi elastic scattering of muon anti-neutrino off ^{12}C

   Deepika Grover🇮🇳 · Kapil Saraswat🇮🇳 · Prashant Shukla🇮🇳 · Venktesh Singh🇮🇳

   In this work, we study charged current quasi elastic scattering of muon anti-neutrino off nucleon and nucleus using a formalism based on Llewellyn Smith (LS) model. Parameterizations by Galster et al. are used for electric and magnetic Sach's form factors of nucleons. We use Fermi gas model along with Pauli suppression condition to take into account the nuclear effects in anti-neutrino - nucleus QES. We calculate muon anti-neutrino-p and muon anti-neutrino-^{12}C charged current quasi elastic scattering differential and total cross sections for different values of axial mass M_{A} and compare the results with data from GGM, SKAT, BNL, NOMAD, MINERvA and MiniBooNE experiments. The present theoretical approach gives an excellent description of differential cross section data. The calculations with axial mass M_{A} = 0.979 and 1.05 GeV are compatible with data from most of the experiments.

   hep-phnucl-thCPC(2018)·3 citations
3. 03*

   Z polarization in $e^{+}{e}^{-}\to ZWW$ for testing special interactions of massive particles

   Fernand M. Renard🇫🇷

   We show that the $ZWW$ production process may give complementary informations about scale dependent heavy particle masses and possible final state interactions as compared to previously studied top quark production processes. We illustrate the $p_Z$ distribution of the rate of longitudinal $Z_L$ component showing its sensitivity to these effects which may arise from heavy particle substructure or a dark matter (DM) environment.

   hep-ph5 citations
4. 04*

   Bose-Einstein condensation and pion stars

   Jens O. Andersen🇳🇴 · Patrick Kneschke🇳🇴

   Pion stars consisting of Bose-Einstein condensed charged pions have recently been proposed as a new class of compact stars. We use the two-particle irreducible effective action to leading order in the $1/N$-expansion to describe charged and neutrals pions as well as the sigma particle. Tuning the parameters in the Lagrangian correctly, the onset of Bose-Einstein condesation of charged pions is exactly at ${\mu }_I=m_{\pi }$, where ${\mu }_I$ is the isospin chemical potential. We calculate the pressure, energy density, and equation of state, which are used as input to the Tolman-Oppenheimer-Volkov equations. Solving these equations, we obtain the mass radius-relation for pion stars. Global electric charge neutrality is ensured by adding the contribution to the pressure and energy density from a gas of free relativistic leptons. We compare our results with those of recent lattice simulations and find good agreement. The masses of the pion stars are up to approximately 200 solar masses while the corresponding radii are of the order of $10^5$ km.

   hep-ph30 citations
5. 05*

   Features of forward $\pi N$ scattering from a Reggeized model

   Kook-Jin Kong🇰🇷 · Byung-Geel Yu🇰🇷

   Charge exchange process ${\pi }^{-}p\to {\pi }^{0}n$ and elastic scatterings ${\pi }^{\pm }p\to {\pi }^{\pm }p$ are investigated within the Regge framework where the relativistic Born amplitude is reggeized for the $t$-channel meson exchange. Charge exchange cross section is featured by the single $\rho$ exchange. Additional correction by Regge cuts, $\rho$-$f_2$ and $\rho$-Pomeron, agree with differential cross sections and new trajectory for the ${\rho }^{\prime }(1450)$ exchange is attempted to reproduce polarization data. For the description of elastic scattering data up to pion momentum $P_{\mathrm{Lab}}\approx 250$ GeV/c, Pomeron exchange of the Donnachie-Landshoff type is newly constructed and applied in this work. Elastic cross section data are well reproduced with the dominance of $f_2$ and Pomeron exchanges in intermediate and high energies. Analysis of nucleon resonances is presented to test the validity of the present Regge framework below $W\le 2$ GeV.

   hep-phPRC(2018)·6 citations
6. 06*

   Probing stop pair production at the LHC with graph neural networks

   Murat Abdughani🇨🇳 · Jie Ren🇨🇳 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳

   Top-squarks (stops) play a crucial role for the naturalness of supersymmetry (SUSY). However, searching for the stops is a tough task at the LHC. To dig the stops out of the huge LHC data, various expert-constructed kinematic variables or cutting-edge analysis techniques have been invented. In this paper, we propose to represent collision events as event graphs and use the message passing neutral network (MPNN) to analyze the events. As a proof-of-concept, we use our method in the search of the stop pair production at the LHC, and find that our MPNN can efficiently discriminate the signal and background events. In comparison with other machine learning methods (e.g. DNN), MPNN can enhance the mass reach of stop mass by several tens of GeV to over a hundred GeV.

   hep-phhep-exJHEP(2019)·89 citations
7. 07*

   Meson-baryon coupling constants of the SU(3) baryons with flavor SU(3) symmetry breaking

   Ghil-Seok Yang🇰🇷 · Hyun-Chul Kim🇰🇷

   We investigate the strong coupling constants for the baryon octet-octet, decuplet-octet, and decuplet-decuplet vertices with pseudoscalar mesons within a general framework of the chiral quark-soliton model, taking into account the effects of flavor SU(3) symmetry breaking to linear order in the expansion of the strange current quark mass. All relevant dynamical parameters are fixed by using the experimental data on hyperon semileptonic decays and the singlet axial-vector constant of the nucleon. The results of the strong coupling constants for the baryon octet and the pseudoscalar meson octet are compared with those determined from the Jülich-Bonn potential and the Nijmegen extended soft-core potential for hyperon-nucleon scattering. The results of the strong decay widths of the baryon decuplet are in good agreement with the experimental data. The effects of $S{U}_f(3)$ symmetry breaking are sizable on the ${\eta }^{\prime }$ coupling constants. We predict also the strong coupling constants for the $\Omega$ baryons.

   hep-phhep-exnucl-exnucl-thPLB(2018)·20 citations
8. 08*

   NNLO QCD Corrections to W+jet Production in NNLOJET

   Aude Gehrmann-De Ridder🇨🇭 · Thomas Gehrmann🇨🇭 · Nigel Glover🇬🇧 · Alexander Huss🇨🇭 · Duncan Walker🇬🇧

   We give an overview of our calculation of the next-to-next-to-leading order (NNLO) QCD corrections to W + jet production in hadronic collisions. Phenomenological results for multiple differential distributions are compared to CMS data for 8 TeV proton-proton collisions. We further discuss the application of the calculation to the transverse momentum spectrum of inclusive W boson production, again accompanied by a comparison to 8 TeV CMS data. In both cases, the inclusion of NNLO QCD effects give an improved agreement between theory and data with considerably reduced scale uncertainties with respect to the next-to-leading order (NLO) results.

   hep-phPoS(2018)·8 citations
9. 09*

   Proposal of searching for the ${\rm Y}(6S)$ hadronic decays into ${\rm Y}(nS)$ plus ${\eta }^{(\prime )}$

   Qi Huang🇨🇳 · Xiang Liu🇨🇳 · Takayuki Matsuki🇯🇵

   In this work, we propose a possible experimental research topic on the ${\rm Y}(6S)\to {\rm Y}(nS){\eta }^{(\prime )}$ ($n=1,2,3$) transitions. Considering the hadronic loop effect from the intermediate $S$-wave $B_{(s)}$ and $B_{(s)}^{\ast }$ mesons, we estimate the partial decay widths and the corresponding branching ratios of the ${\rm Y}(6S)\to {\rm Y}(nS){\eta }^{(\prime )}$ hadronic decays, which become considerably large. With the running of the Belle II experiment, it becomes possible to explore these ${\rm Y}(6S)\to {\rm Y}(nS){\eta }^{(\prime )}$ transitions.

   hep-phPRD(2018)·12 citations
10. 10*

    On next-to-leading power threshold corrections in Drell-Yan production at N${}^3$LO

    Nadia Bahjat-Abbas🇬🇧 · J. Sinninghe Damsté🇳🇱 · Leonardo Vernazza🇳🇱 · Chris D. White🇬🇧

    The cross-section for Drell-Yan production of a vector boson has been previously calculated at next-to-next-to-leading order, supplemented by enhanced logarithmic terms associated with the threshold region. In this paper, we calculate a large set of enhanced terms associated with the colour structure $C_F^3$ at N${}^3$LO, for the double real emission contribution in the quark-antiquark channel, as an expansion around the threshold region up to and including the first subleading power. We perform our calculation using the method of regions, which systematically characterises all contributions according to whether the virtual gluon is (next-to) soft, collinear or hard in nature. Our results will prove useful for developing general formalisms for classifying next-to-leading power (NLP) threshold effects. They are also interesting in their own right, given that they constitute a previously unknown contribution to the Drell-Yan cross-section at $\mathcal{O}({\alpha }_s^3)$.

    hep-phhep-thJHEP(2018)·41 citations
11. 11*

    Statistical challenges in the search for dark matter

    Sara Algeri🇬🇧 · Melissa van Beekveld🇳🇱 · Nassim Bozorgnia🇬🇧 · Alyson Brooks🇺🇸 · J. Alberto Casas🇪🇸 · Jessi Cisewski-Kehe🇺🇸 · Francis-Yan Cyr-Racine🇺🇸 · Thomas D. P. Edwards🇳🇱 · Fabio Iocco🇧🇷 · Bradley J. Kavanagh🇳🇱 · Judita Mamužić🇪🇸 · Siddharth Mishra-Sharma🇺🇸 and 10 other authors

    The search for the particle nature of dark matter has given rise to a number of experimental, theoretical and statistical challenges. Here, we report on a number of these statistical challenges and new techniques to address them, as discussed in the DMStat workshop held Feb 26 - Mar 3 2018 at the Banff International Research Station for Mathematical Innovation and Discovery (BIRS) in Banff, Alberta.

    hep-phastro-ph.CO7 citations
12. 12*

    JETSCAPE v1.0 Quickstart Guide

    Kolja Kauder (for the JETSCAPE Collaboration)🇺🇸

    The JETSCAPE collaboration announced the first public release of its framework and Monte Carlo event generator at this conference, providing a unified interface and a comprehensive suite of model implementations for all stages of ultra-relativistic heavy ion collisions. This release focuses on validation of the framework and the $pp$ reference. A full manual is under development. In the mean-time, these proceedings will provide a guide for installation and simulation runs in lieu of the more traditional summary of the presentation.

    hep-phnucl-thNPA(2019)·23 citations
13. 13*

    Ergoregion instability of exotic compact objects: electromagnetic and gravitational perturbations and the role of absorption

    Elisa Maggio🇮🇹 · Vitor Cardoso🇵🇹 · Sam R. Dolan🇬🇧 · Paolo Pani🇮🇹

    Spinning horizonless compact objects may be unstable against an 'ergoregion instability'. We investigate this mechanism for electromagnetic perturbations of ultracompact Kerr-like objects with a reflecting surface, extending previous (numerical and analytical) work limited to the scalar case. We derive an analytical result for the frequency and the instability time scale of unstable modes which is valid at small frequencies. We argue that our analysis can be directly extended to gravitational perturbations of exotic compact objects in the black-hole limit. The instability for electromagnetic and gravitational perturbations is generically stronger than in the scalar case and it requires larger absorption to be quenched. We argue that exotic compact objects with spin $\chi \lesssim 0.7$ ($\chi \lesssim 0.9$) should have an absorption coefficient of at least $0.3\%$ ($6\%$) to remain linearly stable, and that an absorption coefficient of at least $\approx 60\%$ would quench the instability for any spin. We also show that - in the static limit - the scalar, electromagnetic, and gravitatonal perturbations of the Kerr metric are related to one another through Darboux transformations.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2019)·129 citations
14. 14*

    A Dark Matter Hurricane: Measuring the S1 Stream with Dark Matter Detectors

    Ciaran A. J. O'Hare🇪🇸 · Christopher McCabe🇬🇧 · N. Wyn Evans🇬🇧 · GyuChul Myeong🇬🇧 · Vasily Belokurov🇬🇧

    The recently discovered S1 stream passes through the Solar neighbourhood on a low inclination, counter-rotating orbit. The progenitor of S1 is a dwarf galaxy with a total mass comparable to the present-day Fornax dwarf spheroidal, so the stream is expected to have a significant DM component. We compute the effects of the S1 stream on WIMP and axion detectors as a function of the density of its unmeasured dark component. In WIMP detectors the S1 stream supplies more high energy nuclear recoils so will marginally improve DM detection prospects. We find that even if S1 comprises less than 10% of the local density, multi-ton xenon WIMP detectors can distinguish the S1 stream from the bulk halo in the relatively narrow mass range between 5 and 25 GeV. In directional WIMP detectors such as CYGNUS, S1 increases DM detection prospects more substantially since it enhances the anisotropy of the WIMP signal. Finally, we show that axion haloscopes possess by far the greatest potential sensitivity to the S1 stream. Once the axion mass has been discovered, the distinctive velocity distribution of S1 can easily be extracted from the axion power spectrum.

    ↳ astro-ph.COastro-ph.GAhep-exhep-phPRD(2018)·97 citations
15. 15*

    Failure of the stochastic approach to inflation beyond slow-roll

    Diego Cruces🇪🇸 · Cristiano Germani🇪🇸 · Tomislav Prokopec🇳🇱

    After giving a pedagogical review we clarify that the stochastic approach to inflation is generically reliable only at zeroth order in the (geometrical) slow-roll parameter ${ϵ}_1$ if and only if ${ϵ}_2^2\ll 6/{ϵ}_1$, with the notable exception of slow-roll. This is due to the failure of the stochastic $\Delta N$ formalism in its standard formulation. However, by keeping the formalism in its regime of validity, we showed that, in ultra-slow-roll, the stochastic approach to inflation reproduces the power spectrum calculated from the linear theory approach.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2019)·80 citations
16. 16*

    A tale of two Regge limits

    Vittorio Del Duca🇨🇭

    In light of the strong advances in understanding the mathematical structure of scattering amplitudes, we discuss the Regge limit of QCD and of the $\mathcal{N}=4$ Super Yang-Mills theory.

    ↳ hep-thhep-phEPJ Web Conf.(2018)·1 citation
17. 17*

    Dark Energy in light of Multi-Messenger Gravitational-Wave astronomy

    Jose María Ezquiaga🇪🇸 · Miguel Zumalacárregui🇺🇸

    Gravitational waves (GWs) provide a new tool to probe the nature of dark energy (DE) and the fundamental properties of gravity. We review the different ways in which GWs can be used to test gravity and models for late-time cosmic acceleration. Lagrangian-based gravitational theories beyond general relativity (GR) are classified into those breaking fundamental assumptions, containing additional fields and massive graviton(s). In addition to Lagrangian based theories we present the effective theory of DE and the $\mu$-$\Sigma$ parametrization as general descriptions of cosmological gravity. Multi-messenger GW detections can be used to measure the cosmological expansion (standard sirens), providing an independent test of the DE equation of state and measuring the Hubble parameter. Several key tests of gravity involve the cosmological propagation of GWs, including anomalous GW speed, massive graviton excitations, Lorentz violating dispersion relation, modified GW luminosity distance and additional polarizations, which may also induce GW oscillations. We summarize present constraints and their impact on DE models, including those arising from the binary neutron star merger GW170817. Upgrades of LIGO-Virgo detectors to design sensitivity and the next generation facilities such as LISA or Einstein Telescope will significantly improve these constraints in the next two decades.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ph+1Front.Astron.Space Sci.(2018)·236 citations
18. 18*

    Self-Generated Cosmic-Ray Confinement in TeV Halos: Implications for TeV Gamma-Ray Emission and the Positron Excess

    Carmelo Evoli🇮🇹 · Tim Linden🇺🇸 · Giovanni Morlino🇮🇹

    Recent observations have detected extended TeV gamma-ray emission surrounding young and middle-aged pulsars. The morphology of these "TeV halos" requires cosmic-ray diffusion to be locally suppressed by a factor of ~100-1000 compared to the typical interstellar medium. No model currently explains this suppression. We show that cosmic-ray self-confinement can significantly inhibit diffusion near pulsars. The steep cosmic-ray gradient generates Alfven waves that resonantly scatter the same cosmic-ray population, suppressing diffusion within ~20 pc of pulsars younger than ~100 kyr. In this model, TeV halos evolve through two phases, a growth phase where Alfven waves are resonantly generated and cosmic-ray diffusion becomes increasingly suppressed, and a subsequent relaxation phase where the diffusion coefficient returns to the standard interstellar value. Intriguingly, cosmic-rays are not strongly confined early in the TeV halo evolution, allowing a significant fraction of injected e+e- to escape. If these e+e- also escape from the surrounding supernova remnant, they would provide a natural explanation for the positron excess observed by PAMELA and AMS-02. Recently created TeV cosmic-rays are confined in the TeV halo, matching observations by HAWC and H.E.S.S. While our default model relaxes too rapidly to explain the confinement of TeV cosmic rays around mature pulsars, such as Geminga, models utilizing a Kraichnan turbulence spectrum experience much slower relaxation. Thus, observations of TeV halos around mature pulsars may provide a probe into our understanding of interstellar turbulence.

    ↳ astro-ph.HEastro-ph.GAhep-phPRD(2018)·138 citations
19. 19*

    On the Prospect of Studying Nonperturbative QED with Beam-Beam Collisions

    V. Yakimenko🇺🇸 · S. Meuren🇺🇸 · F. Del Gaudio🇵🇹 · C. Baumann🇩🇪 · A. Fedotov🇷🇺 · F. Fiuza🇺🇸 · T. Grismayer🇵🇹 · M.J. Hogan🇺🇸 · A. Pukhov🇩🇪 · L.O. Silva🇵🇹 · G. White🇺🇸

    We demonstrate the possibility of probing for the first time the fully nonperturbative regime of quantum electrodynamics. By using tightly compressed and focused electron beams in a 100 GeV-class particle collider, beamstrahlung radiation losses can be mitigated, allowing the particles to experience extreme electromagnetic fields. Three-dimensional particle-in-cell simulations confirm the viability of this approach. The experimental forefront envisaged has the potential to establish a novel research field and to stimulate the development of a new theoretical methodology for this yet unexplored regime of strong-field quantum electrodynamics.

    ↳ physics.plasm-phhep-phphysics.acc-phPRL(2019)·160 citations
20. 20*

    On Magneticons and some related matters

    David Fryberger🇺🇸

    The name "magneticon" in this paper refers to a magnetically charged spin 1/2 particle predicted by incorporating a symmetry of classical electromagnetism, called dyality symmetry, into a certain model for the structure of point-like fermions. (Actually, it is anticipated that there would be a full spectrum, both hadronic and leptonic, of such magnetically charged particles.) The lightest of these magneticons is anticipated to be leptonic in nature and predicted to have the same magnitude of electromagnetic charge (in Gaussian units) as the electron, except that it is magnetic. Accompanying this spectrum of magnetic fermions, it is suggested that there may also be a second, or magnetic, photon. After a brief introduction, the pair production cross section of magneticons by electron-positron annihilation is derived using a lowest order quantum perturbation approximation suggested by a two-potential Lagrangian form for classical electromagnetism, symmetrized through the use of space-time algebra to include magnetic charge and currents. A discussion of how these ideas might be included in other quantum interactions involving magnetic charges and the magnetic photon is undertaken. These interactions include electron-magneticon scattering and magneticon vacuum polarization loops. Possibilities for the observation of these magnetic particles in past experiments, as well as future experiments, are explored, and some predictions are made.

    ↳ physics.gen-phhep-ph1 citation
21. 21*

    Inflaton candidates: from string theory to particle physics

    K. Sravan Kumar

    Cosmic inflation is the cornerstone of modern cosmology. In particular, following the Planck mission reports presented in 2015 regarding cosmic microwave background (CMB), there is an increasing interest in searching for inflaton candidates within fundamental theories and to ultimately test them with future CMB data. This thesis presents inflationary models using a methodology that can be described as venturing top-down or bottom-up along energy scales. In the top-down motivation, we study inflationary scenarios in string theory and supergravity (SUGRA), namely with (multiple) 3-forms, Dirac-Born-Infeld Galileon model, a string field theory setup and $\mathcal{N}=1$ SUGRA $\alpha -$attractor models. In the bottom-up motivation, we construct a grand unified theory based inflationary model with an additional conformal symmetry and study not only inflation but also provide predictions related to particle physics. Our research work includes various classes of inflation driven by scalar fields under a canonical, non-canonical and induced gravity frameworks. All these models are consistent with Planck data, supported by key primordial cosmological parameters such as the scalar spectral index $n_s$, the tensor to scalar ratio $r$, together with the primordial non-Gaussianities. Future probes aiming to detect primordial gravitational waves and CMB non-Gaussianities can further help to distinguish between them.

    ↳ hep-thastro-ph.COgr-qchep-ph4 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.