Mon·Apr 10, 2017Monday·April 10, 2017

1. 01*

   Phase Transitions and Baryogenesis From Decays

   Brian Shuve🇺🇸 · Carlos Tamarit🇬🇧

   We study scenarios in which the baryon asymmetry is generated from the decay of a particle whose mass originates from the spontaneous breakdown of a symmetry. This is realized in many models, including low-scale leptogenesis and theories with classical scale invariance. Symmetry breaking in the early universe proceeds through a phase transition that gives the parent particle a time-dependent mass, which provides an additional departure from thermal equilibrium that could modify the efficiency of baryogenesis from out-of-equilibrium decays. We characterize the effects of various types of phase transitions and show that an enhancement in the baryon asymmetry from decays is possible if the phase transition is of the second order, although such models are typically fine-tuned. We also stress the role of new annihilation modes that deplete the parent particle abundance in models realizing such a phase transition, reducing the efficacy of baryogenesis. A proper treatment of baryogenesis in such models therefore requires the inclusion of the effects we study in this paper.

   hep-phastro-ph.COJHEP(2017)·14 citations
2. 02*

   Search for single production of vector-like top partners at the Large Hadron Electron Collider

   Yao-Bei Liu🇨🇳

   The new vector-like top partners with charge $2/3$ are a typical feature of many new physics models beyond the Standard Model (SM). We propose a search strategy for single production of top partners $T$ focusing on both the $T\to Wb$ and $T\to th$ decay channels at the Large Hadron Electron Collider (LHeC). Our analysis is based on a simplified model in which the top partner is an $SU(2)$ singlet, with couplings only to the third generation of SM quarks. We study the observability of the single $T$ through the processes $e^{+}p\to T(\to b{W}^{+}){\bar{\nu }}_e\to b{\ell }^{+}+/E_T^{miss}$ and $e^{+}p\to T(\to th){\bar{\nu }}_e\to t(\to j{j}^{\prime }b)h(\to b\bar{b})/E_T^{miss}$ at the LHeC with the proposed 140 GeV electron beam (with $80\%$ polarization) and 7 TeV proton beam. For three typical $T$-quark masses (800, 900 and 1000 GeV), the $3\sigma$ exclusion limits on the $TWb$ coupling are respectively presented for various values of the integrated luminosity.

   hep-phNPB(2017)·24 citations
3. 03*

   Generation of radiative neutrino mass in the linear seesaw framework, charged lepton flavor violation and dark matter

   Arindam Das🇰🇷 · Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼 · Sourov Roy🇮🇳

   We investigate a model with local U(1)${}_{B-L}$ and discrete $Z_2$ symmetries where two types of weak isospin singlet neutrinos, vector-like charged lepton and exotic scalar fields are introduced. The linear seesaw mechanism is induced at one-loop level through Yukawa interactions associated with the standard model leptons and exotic fields. We also discuss lepton flavor violation and muon anomalous dipole magnetic moment induced by the new Yukawa interaction. In addition, our model has dark matter candidate which is the lightest $Z_2$ odd neutral particle. We calculate the relic density and constraints from direct detection.

   hep-phhep-exPRD(2017)·76 citations
4. 04*

   Interpreting the 3 TeV $WH$ Resonance as a $W^{\prime }$ boson

   Kingman Cheung🇹🇼 · Wai-Yee Keung🇺🇸 · Chih-Ting Lu🇹🇼 · Po-Yan Tseng🇯🇵

   Motivated by a local $3.2-3.4$ sigma resonance in $WH$ and $ZH$ in the ATLAS Run 2 data, we attempt to interpret the excess in terms of a $W^{\prime }$ boson in a $SU(2{)}_1\times SU(2{)}_2\times U(1{)}_X$ model. We stretch the deviation from the alignment limit of the Equivalence Theorem, so as to maximize $WH$ production while keeping the $WZ$ production rate below the experimental limit. We found a viable though small region of parameter space that satisfies all existing constraints on $W^{\prime }\to jj,t\bar{b},WZ$, as well as the precision Higgs data. The cross section of $W^{\prime }\to WH$ that we obtain is about $5-6$ fb.

   hep-phJHEP(2017)·1 citation
5. 05*

   Dynamical formation of center domains in quark-gluon plasma

   Jakapat Kannika🇹🇭 · Christoph Herold🇹🇭 · Ayut Limphirat🇹🇭 · Chinorat Kobdaj🇹🇭 · Yupeng Yan🇹🇭

   We study the formation of domain structures due to spontaneous breakdown of center symmetry at high temperatures in quenched QCD. We develop a phenomenological model for the explicit propagation of the Polyakov loop as the relevant order parameter of the deconfinement phase transition. The surface tension in the equation of motion is fit in comparison with lattice QCD data. Results give insight into the dynamical formation of center domains as well as the formation of energy bands along domain walls and let us estimate the required time to form such structures above the critical temperature.

   hep-phPRC(2017)·1 citation
6. 06*

   Analysis of $pp$ and $\bar{p}p$ Elastic Scattering Based on Theoretical Bounds in High-Energy Physics: an Update

   V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺 · S. D. Campos (Universidade Federal de São Carlos)🇧🇷

   In a previous work a novel parametrization was proposed for the $pp$ and $\bar{p}p$ total cross section. Here, results are presented for analysis updated with taken into account the recent data from accelerator experiments as well as from cosmic ray measurements. The analytic parameterizations suggested within axiomatic quantum field theory (AQFT) provide the quantitative description of energy dependence of global scattering observables with robust values of fit parameters. Based on the fit results the estimations are derived for the total cross section and the $\rho$ parameter in elastic $pp$ scattering at various $\sqrt{s}$ up to energy frontier $\sqrt{s}=10$ PeV which can be useful for present and future hadron colliders as well as for cosmic ray measurements at ultra-high energies.

   hep-phhep-exInt.J.Mod.Phys.A(2017)·9 citations
7. 07*

   Dark matter self-interactions from a general spin-0 mediator

   Felix Kahlhoefer🇩🇪 · Kai Schmidt-Hoberg🇩🇪 · Sebastian Wild🇩🇪

   Dark matter particles interacting via the exchange of very light spin-0 mediators can have large self-interaction rates and obtain their relic abundance from thermal freeze-out. At the same time, these models face strong bounds from direct and indirect probes of dark matter as well as a number of constraints on the properties of the mediator. We investigate whether these constraints can be consistent with having observable effects from dark matter self-interactions in astrophysical systems. For the case of a mediator with purely scalar couplings we point out the highly relevant impact of low-threshold direct detection experiments like CRESST-II, which essentially rule out the simplest realization of this model. These constraints can be significantly relaxed if the mediator has CP-violating couplings, but then the model faces strong constraints from CMB measurements, which can only be avoided in special regions of parameter space.

   hep-phastro-ph.COJCAP(2017)·121 citations
8. 08*

   Charm-beauty meson bound states from $B(B^{\ast })D(D^{\ast })$ and $B(B^{\ast })\bar{D}({\bar{D}}^{\ast })$ interaction

   S. Sakai🇪🇸 · L. Roca🇪🇸 · E. Oset🇪🇸

   We evaluate the s-wave interaction of pseudoscalar and vector mesons with both charm and beauty to investigate the possible existence of molecular $BD$, $B^{\ast }D$, $B{D}^{\ast }$, $B^{\ast }{D}^{\ast }$, $B\bar{D}$, $B^{\ast }\bar{D}$, $B{\bar{D}}^{\ast }$ or $B^{\ast }{\bar{D}}^{\ast }$ meson states. The scattering amplitude is obtained implementing unitarity starting from a tree level potential accounting for the dominant vector meson exchange. The diagrams are evaluated using suitable extensions to the heavy flavor sector of the hidden gauge symmetry Lagrangians involving vector and pseudoscalar mesons{, respecting heavy quark spin symmetry}. We obtain bound states at energies above 7 GeV for $BD$ ($J^P=0^{+}$), $B^{\ast }D$ ($1^{+}$), $B{D}^{\ast }$ ($1^{+}$) and $B^{\ast }{D}^{\ast }$ ($0^{+}$, $1^{+}$, $2^{+}$), all in isospin 0. For $B\bar{D}$ ($0^{+}$), $B^{\ast }\bar{D}$ ($1^{+}$), $B{\bar{D}}^{\ast }$ ($1^{+}$) and $B^{\ast }{\bar{D}}^{\ast }$ ($0^{+}$, $1^{+}$, $2^{+}$) we also find similar bound states in $I=0$, but much less bound, which would correspond to exotic meson states with $\bar{b}$ and $\bar{c}$ quarks, and for the $I=1$ we find a repulsive interaction. We also evaluate the scattering lengths in all cases, which can be tested in current investigations of lattice QCD.

   hep-phPRD(2017)·74 citations
9. 09*

   $Z\to l_i^{\pm }{l}_j^{\mp }$ processes in the BLMSSM

   Xing-Xing Dong🇨🇳 · Shu-Min Zhao🇨🇳 · Xi-Jie Zhan🇨🇳 · Zhong-Jun Yang🇨🇳 · Hai-Bin Zhang🇨🇳 · Tai-Fu Feng🇨🇳

   In a supersymmetric extension of the Standard Model(SM) where baryon and lepton numbers are local gauge symmetries (BLMSSM), we investigate the charged lepton flavor violating (CLFV) processes $Z\to l_i^{\pm }{l}_j^{\mp }$ after introducing the new gauginos and the right-handed neutrinos. In this model, the branching ratios of $Z\to l_i^{\pm }{l}_j^{\mp }$ are around ($10^{-8}\sim 10^{-10}$), which approach the present experimental upper bounds. We hope that the branching ratios for these CLFV processes can be detected in the near future.

   hep-phCPC(2017)·4 citations
10. 10*

    A study of jet mass distributions with grooming

    Simone Marzani🇺🇸 · Lais Schunk🇫🇷 · Gregory Soyez🇫🇷

    We perform a phenomenological study of the invariant mass distribution of hadronic jets produced in proton-proton collisions, in conjunction a grooming algorithm. In particular, we consider the modified MassDrop Tagger (mMDT), which corresponds to Soft Drop with angular exponent $\beta =0$. Our calculation, which is differential in both jet mass and jet transverse momentum, resums large logarithms of the jet mass, including the full dependence on the groomer's energy threshold $z_{\text{cut}}$, and it is matched to fixed-order QCD matrix elements at next-to-leading order. In order to account for non-perturbative contributions, originating from the hadronisation process and from the underlying event, we also include a phenomenological correction factor derived from Monte Carlo parton-shower simulations. Furthermore, we consider two different possibilities for the jet transverse momentum: before or after grooming. We show that the former should be preferred for comparisons with upcoming experimental data essentially because the mMDT transverse momentum spectrum is not collinear safe.

    hep-phJHEP(2017)·118 citations
11. 11*

    Top and bottom partners, Higgs boson on the brane, and the tth signal

    Gilles Couture🇨🇦 · Mariana Frank🇨🇦 · Cherif Hamzaoui🇨🇦 · Manuel Toharia🇨🇦

    Current LHC results indicate a possible enhancement in the production of Higgs bosons in association with top quarks (tth) over the Standard Model (SM) expectations, suggesting an increase in the top Yukawa coupling. To explain these results, we study the effect of adding to the SM a small set of vector-like partners of the top and bottom quarks with masses of order ~1 TeV. We consider Yukawa coupling matrices with vanishing determinant and show that then, Higgs production through gluon fusion is not affected by deviations in the top quark Yukawa coupling, and in fact depends only on deviations in the bottom quark Yukawa coupling. We call this scenario the "Brane Higgs Limit", as it can emerge naturally in models of warped extra-dimensions with all matter fields in the bulk, except the Higgs (although it could also occur in 4D scenarios with vector-like quarks and special flavor symmetries forcing the vanishing of the Yukawa determinants). We show that the scenario is highly predictive for all Higgs production/decay modes, making it easily falsifiable, maybe even at the LHC RUN 2 with higher luminosity.

    hep-phPRD(2017)·8 citations
12. 12*

    Improved Determination of the ${}^{235}\text{U}$ and ${}^{239}\text{Pu}$ Reactor Antineutrino Cross Sections per Fission

    Carlo Giunti🇮🇹

    We present the results of a combined fit of the reactor antineutrino rates and the Daya Bay measurement of ${\sigma }_{f,235}$ and ${\sigma }_{f,239}$. The combined fit leads to a better determination of the two cross sections per fission: ${\sigma }_{f,235}=6.29\pm 0.08$ and ${\sigma }_{f,239}=4.24\pm 0.21$ in units of $10^{-43}{\text{cm}}^2/\text{fission}$, with respective uncertainties of about $1.2\%$ and $4.9\%$. Since the respective deviations from the theoretical cross sections per fission are $2.5\sigma$ and $0.7\sigma$, we conclude that, if the reactor antineutrino anomaly is not due to active-sterile neutrino oscillations, it is likely that it can be solved with a revaluation of the ${}^{235}\text{U}$ reactor antineutrino flux. However, the ${}^{238}\text{U}$, ${}^{239}\text{Pu}$, and ${}^{241}\text{Pu}$ fluxes, which have larger uncertainties, could also be significantly different from the theoretical predictions.

    hep-phhep-exnucl-exnucl-thPRD(2017)·23 citations
13. 13*

    New prospects for the numerical calculation of Mellin-Barnes integrals in Minkowskian kinematics

    Ievgen Dubovyk🇩🇪 · Janusz Gluza🇵🇱 · Tomasz Jelinski🇵🇱 · Tord Riemann🇵🇱 · Johann Usovitsch🇩🇪

    During the last several years remarkable progress has been made in numerical calculations of dimensionally regulated multi-loop Feynman diagrams using Mellin-Barnes (MB) representations. The bottlenecks were non-planar diagrams and Minkowskian kinematics. The method has been proved to work in highly non-trivial physical application (two-loop electroweak bosonic corrections to the $Z\to b\bar{b}$ decay), and cross-checked with the sector decomposition (SD) approach. In fact, both approaches have their pros and cons. In calculation of multidimensional integrals, depending on masses and scales involved, they are complementary. A powerful top-bottom approach to the numerical integration of multidimensional MB integrals is automatized in the MB-suite AMBRE/MB/ MBtools/MBnumerics/CUBA. Key elements are a dedicated use of the Cheng-Wu theorem for non-planar topologies and of shifts and deformations of the integration contours. An alternative bottom-up approach starting with complex 1-dimensional MB-integrals, based on the exploration of steepest descent integration contours in Minkowskian kinematics, is also discussed. Short and long term prospects of the MB-method for multi-loop applications to LHC- and LC-physics are discussed.

    hep-phActa Phys.Polon.B(2017)·18 citations
14. 14*

    Maxi-sizing the trilinear Higgs self-coupling: how large could it be?

    Luca Di Luzio🇬🇧 · Ramona Gröber🇬🇧 · Michael Spannowsky🇬🇧

    In order to answer the question on how much the trilinear Higgs self-coupling could deviate from its Standard Model value in weakly coupled models, we study both theoretical and phenomenological constraints. As a first step, we discuss this question by modifying the Standard Model using effective operators. Considering constraints from vacuum stability and perturbativity, we show that only the latter can be reliably assessed in a model-independent way. We then focus on UV models which receive constraints from Higgs coupling measurements, electroweak precision tests, vacuum stability and perturbativity. We find that the interplay of current measurements with perturbativity already exclude self-coupling modifications above a factor of few with respect to the Standard Model value.

    hep-phhep-exEPJC(2017)·95 citations
15. 15*

    NLO electroweak corrections in general scalar singlet models

    Raul Costa🇵🇹 · Marco O. P. Sampaio🇵🇹 · Rui Santos🇵🇹

    If no new physics signals are found, in the coming years, at the Large Hadron Collider Run-2, an increase in precision of the Higgs couplings measurements will shift the dicussion to the effects of higher order corrections. In Beyond the Standard Model (BSM) theories this may become the only tool to probe new physics. Extensions of the Standard Model (SM) with several scalar singlets may address several of its problems, namely to explain dark matter, the matter-antimatter asymmetry, or to improve the stability of the SM up to the Planck scale. In this work we propose a general framework to calculate one loop-corrections in BSM models with an arbitrary number of scalar singlets. We then apply our method to a real and to a complex scalar singlet models. We assess the importance of the one-loop radiative corrections first by computing them for a tree level mixing sum constraint, and then for the main Higgs production process $gg\to H$. We conclude that, for the currently allowed parameter space of these models, the corrections can be at most a few percent. Notably, a non-zero correction can survive when dark matter is present, in the SM-like limit of the Higgs couplings to other SM particles.

    hep-phhep-thJHEP(2017)·7 citations
16. 16*

    GUT Models at Current and Future Hadron Colliders and Implications to Dark Matter Searches

    Giorgio Arcadi🇩🇪 · Manfred Lindner🇩🇪 · Yann Mambrini🇫🇷 · Mathias Pierre🇫🇷 · Farinaldo S. Queiroz🇩🇪

    Grand Unified Theories (GUT) offer an elegant and unified description of electromagnetic, weak and strong interactions at high energy scales. A phenomenological and exciting possibility to grasp GUT is to search for TeV scale observables arising from Abelian groups embedded in GUT constructions. That said, we use dilepton data (ee and $\mu \mu$) that has been proven to be a golden channel for a wide variety of new phenomena expected in theories beyond the Standard Model to probe GUT-inspired models. Since heavy dilepton resonances feature high signal selection efficiencies and relatively well-understood backgrounds, stringent and reliable bounds can be placed on the mass of the $Z^{\prime }$ gauge boson arising in such theories. In this work, we obtain 95\% C.L. limits on the $Z^{\prime }$ mass for several GUT-models using current and future proton-proton colliders with $\sqrt{s}=13\mathrm{TeV},33\mathrm{TeV},\mathrm{and}100$~TeV, and put them into perspective with dark matter searches in light of the next generation of direct detection experiments.

    hep-phPLB(2017)·21 citations
17. 17*

    Comment on "Lattice Gluon and Ghost Propagators, and the Strong Coupling in Pure $SU(3)$ Yang-Mills Theory: Finite Lattice Spacing and Volume Effects"

    Ph. Boucaud🇫🇷 · F. De Soto🇪🇸 · J. Rodríguez-Quintero🇪🇸 · S. Zafeiropoulos🇺🇸

    The authors of ref. Phys.Rev. D94 (2016) no.1, 014502 reported about a careful analysis of the impact of lattice artifacts on the $SU(3)$ gauge-field propagators. In particular, they found that the low-momentum behavior of the renormalized propagators depends on the lattice bare coupling and interpreted this fact as the result of it being affected by finite lattice spacing artifacts. We do not share this interpretation and present here a different and more suitable explanation for these results.

    ↳ hep-lathep-phPRD(2017)·24 citations
18. 18*

    Jet Constituents for Deep Neural Network Based Top Quark Tagging

    Jannicke Pearkes🇨🇦 · Wojciech Fedorko🇨🇦 · Alison Lister🇨🇦 · Colin Gay🇨🇦

    Recent literature on deep neural networks for tagging of highly energetic jets resulting from top quark decays has focused on image based techniques or multivariate approaches using high-level jet substructure variables. Here, a sequential approach to this task is taken by using an ordered sequence of jet constituents as training inputs. Unlike the majority of previous approaches, this strategy does not result in a loss of information during pixelisation or the calculation of high level features. The jet classification method achieves a background rejection of 45 at a 50% efficiency operating point for reconstruction level jets with transverse momentum range of 600 to 2500 GeV and is insensitive to multiple proton-proton interactions at the levels expected throughout Run 2 of the LHC.

    ↳ hep-excs.LGhep-phstat.ML119 citations
19. 19*

    Vorticity in the QGP liquid and $\Lambda$ polarization at the RHIC Beam Energy Scan

    Iu. Karpenko🇮🇹 · F. Becattini🇮🇹

    Polarization of $\Lambda$ hyperons and their antiparticles is calculated in a 3+1 dimensional viscous hydrodynamic model with initial state from UrQMD hadron/string cascade. We find that, along with recent results from STAR, the mean polarization at fixed centrality decreases as a function of collision energy from 1.5% at $\sqrt{s_{\mathrm{NN}}}=7.7$ GeV to 0.2% at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. We explore the effects which lead to such collision energy dependence, feed-down corrections and a difference between $\Lambda$ and $\bar{\Lambda }$.

    ↳ nucl-thhep-phnucl-exNPA(2017)·20 citations
20. 20*

    Inflationary preheating dynamics with ultracold atoms

    Torsten V. Zache🇩🇪 · Valentin Kasper🇺🇸 · Jürgen Berges🇩🇪

    We discuss the amplification of loop corrections in quantum many-body systems through dynamical instabilities. As an example, we investigate both analytically and numerically a two-component ultracold atom system in one spatial dimension. The model features a tachyonic instability, which incorporates characteristic aspects of the mechanisms for particle production in early-universe inflaton models. We establish a direct correspondence between measureable macroscopic growth rates for occupation numbers of the ultracold Bose gas and the underlying microscopic processes in terms of Feynman loop diagrams. We analyze several existing ultracold atom setups featuring dynamical instabilities and propose optimized protocols for their experimental realization. We demonstrate that relevant dynamical processes can be enhanced using a seeding procedure for unstable modes and clarify the role of initial quantum fluctuations and the generation of a non-linear secondary stage for the amplification of modes.

    ↳ cond-mat.quant-gashep-phPRA(2017)·22 citations
21. 21*

    First Searches for Axions and Axion-Like Particles with the LUX Experiment

    D.S. Akerib🇺🇸 · S. Alsum🇺🇸 · C. Aquino🇬🇧 · H.M. Araújo🇬🇧 · X. Bai🇺🇸 · A.J. Bailey🇬🇧 · J. Balajthy🇺🇸 · P. Beltrame🇬🇧 · E.P. Bernard🇺🇸 · A. Bernstein🇺🇸 · T.P. Biesiadzinski🇺🇸 · E.M. Boulton🇺🇸 and 89 other authors

    The first searches for axions and axion-like particles with the Large Underground Xenon (LUX) experiment are presented. Under the assumption of an axio-electric interaction in xenon, the coupling constant between axions and electrons, gAe is tested, using data collected in 2013 with an exposure totalling 95 live-days $\times$ 118 kg. A double-sided, profile likelihood ratio statistic test excludes gAe larger than 3.5 $\times$ 10${}^{-12}$ (90% C.L.) for solar axions. Assuming the DFSZ theoretical description, the upper limit in coupling corresponds to an upper limit on axion mass of 0.12 eV/c${}^2$, while for the KSVZ description masses above 36.6 eV/c${}^2$ are excluded. For galactic axion-like particles, values of gAe larger than 4.2 $\times$ 10${}^{-13}$ are excluded for particle masses in the range 1-16 keV/c${}^2$. These are the most stringent constraints to date for these interactions.

    ↳ astro-ph.COhep-phPRL(2017)·190 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.