Fri·May 3, 2019Friday·May 3, 2019

1. 01*

   Is the magnitude of the Peccei-Quinn scale set by the landscape?

   Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Dibyashree Sengupta🇺🇸 · Hasan Serce🇺🇸 · Kuver Sinha🇺🇸 · Robert Wiley Deal🇺🇸

   Rather general considerations of the string theory landscape imply a mild statistical draw towards large soft SUSY breaking terms tempered by the requirement of proper electroweak symmetry breaking where SUSY contributions to the weak scale are not too far from m(weak)~ 100 GeV. Such a picture leads to the prediction that m_h~ 125 GeV while most sparticles are beyond current LHC reach. Here we explore the possibility that the magnitude of the Peccei-Quinn (PQ) scale f_a is also set by string landscape considerations within the framework of a compelling SUSY axion model. First, we examine the case where the PQ symmetry arises as an accidental approximate global symmetry from a more fundamental gravity-safe Z(24)^R symmetry and where the SUSY mu parameter arises from a Kim-Nilles operator. The pull towards large soft terms then also pulls the PQ scale as large as possible. Unless this is tempered by rather severe (unknown) cosmological or anthropic bounds on the density of dark matter, then we would expect a far greater abundance of dark matter than is observed. This conclusion cannot be negated by adopting a tiny axion misalignment angle theta_i because WIMPs are also overproduced at large f_a. Hence, we conclude that setting the PQ scale via anthropics is highly unlikely. Instead, requiring soft SUSY breaking terms of order the gravity-mediation scale m_{3/2}~ 10-100 TeV places the mixed axion-neutralino dark matter abundance into the intermediate scale sweet zone where f_a~ 10^{11}-10^{12} GeV. We compare our analysis to the more general case of a generic SUSY DFSZ axion model with uniform selection on theta_i but leading to the measured dark matter abundance: this approach leads to a preference for f_a~ 10^{12} GeV.

   hep-phastro-ph.COEPJC(2019)·10 citations
2. 02*

   Prospects for vectorlike leptons at future proton-proton colliders

   Prudhvi N. Bhattiprolu🇺🇸 · Stephen P. Martin🇺🇸

   Vectorlike leptons are an intriguing possibility for physics beyond the Standard Model. We study the reach for discovering (at 5$\sigma$ significance) or excluding (at 95 per cent confidence) models of charged vectorlike leptons that mix predominantly with the tau, using multi-lepton signatures at various future proton-proton collider options: a high-luminosity LHC with $\sqrt{s}=$ 14 TeV, a high-energy LHC with $\sqrt{s}=$ 27 TeV, and possible new longer-tunnel colliders with $\sqrt{s}=$ 70 or 100 TeV. For weak isodoublet vectorlike leptons, we estimate that a 27 TeV high-energy LHC with 15 ab${}^{-1}$ could exclude masses up to about 2300 GeV, or discover them if the mass is less than about 1700 GeV, while a 100 TeV collider with 30 ab${}^{-1}$ could exclude masses up to about 5750 GeV, or make a discovery if the mass is less than about 4000 GeV. However, we find that weak isosinglet vectorlike leptons present a much more difficult challenge, with some reach for exclusion, but not for discovery at any of the collider options considered.

   hep-phPRD(2019)·87 citations
3. 03*

   Investigate the pentaquark resonance in the $NK$ system

   Xuejie Liu🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

   A dynamical calculation of pentaquark systems with quark contents $uudd\bar{s}$ is performed in the framework of quark delocalization color screening model with the help of resonating group method. The effective potentials between baryon and meson clusters are given, and the possible bound states or resonances are investigated. The single calculations show that the $N{K}^{\ast }$ with $I=0,J^P={\frac{1}{2}}^{-}$, $\Delta K^{\ast }$ with $I=1,J^P={\frac{1}{2}}^{-}$, and $\Delta K^{\ast }$ with $I=2,J^P={\frac{3}{2}}^{-}$ are all bound, but they all turns into scattering states by coupling with the corresponding open channels. A possible resonance state $\Delta K^{\ast }$ with $I=1,J^P={\frac{5}{2}}^{-}$ is proposed. The mass is around $2110.5$ MeV, and the decay modes are $NK$ in $D$-wave or $NK\pi \pi$ in $P$-waves.

   hep-phnucl-thPRC(2019)·6 citations
4. 04*

   Probing the anomalous $tq\gamma$ couplings through single top production at the future lepton-hadron colliders

   E. Alici🇹🇷 · M. Köksal🇹🇷

   The measurements of the top quark flavor changing neutral current interactions are one of the most important goals of the top quark physics program in the present and the future collider experiments. These measurements provide direct information on non-standard interactions of the top quark. Within the framework of new physics beyond the Standard Model, these interactions can be defined by an effective Lagrangian. In this study, we have investigated the potential of the future $\mu p$ colliders on the top quark flavor changing neutral current interactions through the subprocesses $\gamma q\to t\to Wb$ where $q=u,c$. These subprocesses have been produced through the main reaction $\mu p\to \mu \gamma p\to \mu WbX$ at the LHC$-\mu p$, the FCC$-\mu p$ and the SPPC-$\mu p$. For the main reaction, the total cross sections have been calculated as a function of the anomalous $tq\gamma$ couplings. In addition, sensitivities on BR($t\to q\gamma$) at $95\%$ Confidence Level have been calculated. We obtain that the best constraints on BR($t\to q\gamma$) are at the order of 10${}^{-7}$ which is four orders of magnitude better than the LHC's experimental results.

   hep-phMod.Phys.Lett.A(2019)·8 citations
5. 05*

   The signatures of the new particles $h_2$ and $Z_{\mu \tau }$ at e-p colliders in the $U(1{)}_{L_{\mu }-L_{\tau }}$ model

   Jin-Xin Hou🇨🇳 · Chong-Xing Yue🇨🇳

   Considering the superior performances of the future e-p colliders, LHeC and FCC-eh, we discuss the feasibility of detecting the extra neutral scalar $h_2$ and the light gauge boson $Z_{\mu \tau }^{}$, which are predicted by the ${U(1)}_{L_{\mu }^{}-L_{\tau }^{}}$ model. Taking into account the experimental constraints on the relevant free parameters, we consider all possible production channels of $h_2$ and $Z_{\mu \tau }^{}$ at e-p colliders and further investigate their observability through the optimal channels in the case of the beam polarization P($e^{-}$)= -0.8. We find that the signal significance above 5$\sigma$ of $h_2$ as well as $Z_{\mu \tau }^{}$ detecting can be achieved via $e^{-}p\to e^{-}j{h}_2(\to Z_{\mu \tau }{Z}_{\mu \tau })\to e^{-}j+/E_T^{}$ process and a 5$\sigma$ sensitivity of $Z_{\mu \tau }^{}$ detecting can be gained via $e^{-}p\to e^{-}j{h}_1(\to Z_{\mu \tau }^{}{Z}_{\mu \tau }^{})\to e^{-}j+/E_T^{}$ process at e-p colliders with appropriate parameter values and a designed integrated luminosity. However, the signals of $h_2$ decays into pair of SM particles are difficult to be detected.

   hep-phEPJC(2019)·9 citations
6. 06*

   $\Xi (1690{)}^{-}$ resonance production via $K^{-}p\to K^{+}{K}^{-}\Lambda$

   Seung-il Nam🇰🇷 · Jung Keun Ahn🇰🇷

   In this talk, we investigate $\Xi (1690{)}^{-}$ production from the $K^{-}p\to K^{+}{K}^{-}\Lambda$ reaction wit the effective Lagrangian method and consider the $s$- and $u$-channel $\Sigma /\Lambda$ ground states and resonances for the $\Xi$-pole contributions, in addition to the $s$-channel $\Lambda$, $u$-channel nucleon pole, and $t$-channel $K^{-}$-exchange for the $\varphi$-pole contributions. The $\Xi$-pole includes $\Xi (1320)$, $\Xi (1535)$, $\Xi (1690)(J^p=1/2^{-})$, and $\Xi (1820)(J^p=3/2^{-})$. We compute the Dalitz plot density of $(d^2\sigma /d{M}_{K^{+}{K}^{-}}d{M}_{K^{-}\Lambda }$ at 4.2 GeV$/c$) and the total cross sections for the $K^{-}p\to K^{+}{K}^{-}\Lambda$. Employing the parameters from the fit, we present the cross sections for the two-body $K^{-}p\to K^{+}\Xi (1690{)}^{-}$ reaction near the threshold. We also demonstrate that the Dalitz plot analysis for $p_{K^{-}}=1.915\sim 2.065$ GeV/c makes us to explore direct information for $\Xi (1690{)}^{-}$ production, which can be done by future $K^{-}$ beam experiments.

   hep-phhep-exnucl-thJPS Conf.Proc.(2019)·2 citations
7. 07*

   Phase broken $\mu -\tau$ symmetry and the neutrino mass hierarchy

   N. Chamoun🇸🇾 · C. Hamzaoui🇨🇦 · S. Lashin🇪🇬 · S. Nasri🇦🇪 · M. Toharia🇨🇦

   Inspired by the neutrino oscillations data, we consider the exact $\mu -\tau$ symmetry, implemented at the level of the neutrino mass matrix, as a good initial framework around which to study and describe neutrino phenomenology. Working in the diagonal basis for the charged leptons, we deviate from $\mu -\tau$ symmetry by just modifying the phases of the neutrino mass matrix elements. This deviation is enough to allow for a non-vanishing neutrino mixing entry $|V_{e3}|$ (i.e. ${\theta }_{13}$) but it also gives a very stringent (and eventually falsifiable) prediction for the atmospheric neutrino mixing element $|V_{\mu 3}|$ as a function of $|V_{e3}|$. The breaking by phases is characterized by a single phase and is shown to lead to interesting lower bounds on the allowed mass of the lightest neutrino depending on the ordering of neutrino masses (normal or inverted) and on the value of the Dirac $\mathcal{C}\mathcal{P}$ violating phase ${\delta }_{CP}$. The allowed parameter space for the effective Majorana neutrino mass $m_{ee}$ is also shown to be non-trivially constrained.

   hep-phPRD(2021)·18 citations
8. 08*

   Jets in QCD matter: Monte Carlo approaches

   Liliana Apolinário🇵🇹

   Monte Carlo approaches are a powerful tool in collider physics as they allow to make theory-data comparison on complex multi-particle observables, otherwise difficult for perturbative calculations. In heavy-ion collisions, there is a multitude of Monte Carlo approaches that try to address jet quenching phenomena, name given to the collection of medium-induced modifications that high momentum particles and jets undergo when traversing the hot and dense medium that is produced in such collisions. These models are being continuous developed alongside the theoretical efforts to understand and accurately describe experimental results provided by both RHIC and the LHC. In this manuscript, it is given a general overview about the fundamental building blocks that these tools have to address to describe jets in heavy-ion collisions. It follows a comparison on the latest results provided by some of the jet quenching Monte Carlo models to jet and intra-jet observables. A final personal outlook is presented at the end of the manuscript.

   hep-phPoS(2019)·0 citations
9. 09*

   Effective Theories for Quark Flavour Physics

   Luca Silvestrini🇮🇹

   The purpose of these lectures is to provide the reader with an idea of how we can probe New Physics with quark flavour observables using effective theory techniques. After giving a concise review of the quark flavour structure of the Standard Model, we introduce the effective Hamiltonian for quark weak decays. We then consider the effective Hamiltonian for $\Delta F=2$ transitions in the Standard Model and beyond. We discuss how meson-antimeson mixing and CP violation can be described in terms of the $\Delta F=1$ and $\Delta F=2$ effective Hamiltonians. Finally we present the Unitarity Triangle Analysis and discuss how very stringent constraints on New Physics can be obtained from $\Delta F=2$ processes.

   hep-phLes Houches Lect.Notes(2020)·24 citations
10. 10*

    Diffractive excitation in $pp$ and $pA$ collisions at high energies

    V. P. Goncalves🇧🇷 · R. Palota da Silva🇧🇷 · P. V. R. G. Silva🇧🇷

    In this paper we consider the Good - Walker approach for the diffractive excitation and updated the Miettinen -- Pumplin (MP) model for $pp/\bar{p}p$ collisions considering the recent LHC data for the total and elastic $pp$ cross sections. The behavior of the total, elastic and diffractive cross sections is analyzed and predictions for the energies of Run 3 of the LHC and those of the Cosmic Rays experiments are derived. Our results demonstrate that the MP model is able to describe the current data and that it implies that the cross section for the diffraction excitation in $pp$ collisions is almost constant in the energy range probed by the LHC and slowly decreases at higher energies. Our results indicate that the Pumplin bound is not reached at the LHC and Cosmic Ray energies. Moreover, the implications of the diffractive excitation in $pA$ collisions is discussed. In particular, the MP model, constrained by the $pp$ data, is used to derive the main quantities present in the treatment of the diffractive excitation in $pA$ collisions. Predictions for the total, elastic and diffractive $pA$ cross sections are presented considering different nuclei. We demonstrate that the effect of fluctuations decreases at larger energies and heavier nuclei. The energy dependence of the diffractive excitation cross section in $pA$ collisions is estimated for different nuclei and compared with the predictions for the proton dissociation induced by photon interactions.

    hep-phhep-exnucl-thPRD(2019)·10 citations
11. 11*

    Neutrino Mixing via the Neutrino Portal

    Alexei Y Smirnov🇩🇪

    Relation between the lepton and quark mixings: $U_{PMNS}\approx V_{CKM}^{†}{U}_X$, where $U_X$ is the BM or TBM mixing matrices, implies the quark-lepton (Grand) unification and existence of hidden sector with certain flavor symmetries. The latter couples to the visible sector via the neutrino portal and is responsible for $U_X$, as well as for smallness of neutrino mass. GUT ensures appearance of $\sim V_{CKM}$ in the lepton mixing. General features of this scenario (inverse or double seesaw, screening of the Dirac structures, basis fixing symmetry) are described and two realizations are presented. The high energy realization is based on $SO(10)$ GUT with the hidden sector at the Planck scale. The low energy realization includes the 100 TeV scale $L-R$ symmetry and the hidden sector at the keV - MeV scale.

    hep-ph3 citations
12. 12*

    Boosting quantum vacuum signatures by coherent harmonic focusing

    Felix Karbstein🇩🇪 · Alexander Blinne🇩🇪 · Holger Gies🇩🇪 · Matt Zepf🇩🇪

    We show that coherent harmonic focusing provides an efficient mechanism to boost all-optical signatures of quantum vacuum nonlinearity in the collision of high-intensity laser fields, thereby offering a promising route to their first experimental detection. Assuming two laser pulses of given parameters at our disposal, we demonstrate a substantial increase of the number of signal photons measurable in experiments where one of the pulses undergoes coherent harmonic focusing before it collides with the fundamental-frequency pulse. Imposing a quantitative criterion to discern the signal photons from the background of the driving laser photons and accounting for the finite purity of polarization filtering, we find that signal photons arising from inelastic scattering processes constitute a promising signature. By contrast, quasi-elastic contributions which are conventionally assumed to form the most prospective signal remain background dominated. Our findings may result in a paradigm shift concerning which photonic signatures of quantum vacuum nonlinearity are accessible in experiment.

    hep-phquant-phPRL(2019)·38 citations
13. 13*

    A Portalino to the Twin Sector

    Di Liu🇺🇸 · Neal Weiner🇺🇸

    Extensions of the Standard Model are often highly constrained by cosmology. The presence of new states can dramatically alter observed properties of the universe by the presence of additional matter or entropy. In particular, attempts too solve the hierarchy problem through naturalness invariably predict new particles near the weak scale which come into thermal equilibrium. Without a means to deposit this energy into the SM, these models are often excluded. Scenarios of "neutral naturalness" especially, such as the Twin Higgs frequently suffer from this. However, the Portalino, a singlet fermion that marries gauge neutral fermion operators, can naturally help provide a portal for entropy to return to the SM and to lift fermionic degrees of freedom in the Twin Sector. Together with spontaneous breaking of the $Z_2$ $\mathrm{SM}\leftrightarrow \mathrm{Twin}$ symmetry, there are new opportunities to confront the cosmological challenges of these models. Here, we attempt to develop such ideas. We shall show how one can lift many of the light fields by breaking $\text{ztwo}$ with a $U(1{)}_Y$ scalar and its Twin partner. The introduction of Portalinos can lift the remaining degrees of freedom. We shall find that such models are highly constrained by precision SM measurements, motivating moderate extensions beyond this. We will discuss two, one with additional weak matter and another with additional colored matter. The weak model will involve simple two Higgs doublet models on top of $\text{ztwo}$ breaking. The strong model will involve the presence of new leptoquarks and diquarks. We will discuss the implications for neutrino masses from radiative corrections and possible colored signals even within these models of neutral naturalness, some of which might appear at the LHC or future colliders.

    hep-phJHEP(2023)·17 citations
14. 14*

    Equation of state for hot QCD and compact stars from a mean field approach

    Anton Motornenko🇩🇪 · Jan Steinheimer🇩🇪 · Volodymyr Vovchenko🇩🇪 · Stefan Schramm🇩🇪 · Horst Stoecker🇩🇪

    The thermodynamic properties of high temperature and high density QCD-matter are explored within the Chiral SU(3)-flavor parity-doublet Polyakov-loop quark-hadron mean-field model, CMF. The quark sector of the CMF model is tuned to describe the ${\mu }_B=0$ thermodynamics data of lattice QCD. The resulting lines of constant physical variables as well as the baryon number susceptibilities are studied in some detail in the temperature/chemical potential plane. The CMF model predicts three consecutive transitions, the nuclear first-order liquid-vapor phase transition, chiral symmetry restoration, and the cross-over transition to a quark-dominated phase. All three phenomena are cross-over, for most of the $T-{\mu }_B$-plane. The deviations from the free ideal hadron gas baseline at ${\mu }_B=0$ and $T\approx 100-200$ MeV can be attributed to remnants of the liquid-vapor first order phase transition in nuclear matter. The chiral crossing transition determines the baryon fluctuations at much higher ${\mu }_B\approx 1.5$ GeV, and at even higher baryon densities ${\mu }_B\approx 2.4$ GeV, the behavior of fluctuations is controlled by the deconfinement cross-over. The CMF model also describe well the static properties of high ${\mu }_B$ neutron stars as well as the new neutron star merger observations. The effective EoS presented here describes simultaneously lattice QCD results at ${\mu }_B=0$, as well as observed physical phenomena (nuclear matter and neutron star matter) at $T\cong 0$ and high densities, ${\mu }_B>1$ GeV.

    hep-phastro-ph.HEnucl-thPRC(2020)·118 citations
15. 15*

    Gravitational Waves from First-Order Phase Transition in a Simple Axion-Like Particle Model

    P. S. Bhupal Dev🇺🇸 · Francesc Ferrer🇺🇸 · Yiyang Zhang🇺🇸 · Yongchao Zhang🇺🇸

    We consider a gauge-singlet complex scalar field $\Phi$ with a global $U(1)$ symmetry that is spontaneously broken at some high energy scale $f_a$. As a result, the angular part of the $\Phi$-field becomes an axion-like particle (ALP). We show that if the $\Phi$-field has a non-zero coupling $\kappa$ to the Standard Model Higgs boson, there exists a certain region in the $\left(f_a,\kappa \right)$ parameter space where the global $U(1)$ symmetry-breaking induces a strongly first order phase transition, thereby producing stochastic gravitational waves that are potentially observable in current and future gravitational-wave detectors. In particular, we find that future gravitational-wave experiments such as TianQin, BBO and Cosmic Explorer could probe a broad range of the energy scale $10^3\mathrm{GeV}\lesssim f_a\lesssim 10^8\mathrm{GeV}$, independent of the ALP mass. Since all the ALP couplings to the Standard Model particles are proportional to inverse powers of the energy scale $f_a$ (up to model-dependent $\mathcal{O}(1)$ coefficients), the gravitational-wave detection prospects are largely complementary to the current laboratory, astrophysical and cosmological probes of the ALP scenarios.

    hep-phastro-ph.COJCAP(2019)·98 citations
16. 16*

    Global Analysis of Dark Matter Simplified Models with Leptophobic Spin-One Mediators using MasterCode

    E. Bagnaschi🇨🇭 · J.C. Costa🇬🇧 · K. Sakurai🇵🇱 · M. Borsato🇩🇪 · O. Buchmueller🇬🇧 · A. De Roeck🇨🇭 · M.J. Dolan🇦🇺 · J.R. Ellis🇬🇧 · H. Flächer🇬🇧 · K. Hahn🇺🇸 · S. Heinemeyer🇪🇸 · M. Lucio🇪🇸 and 4 other authors

    We report the results of a global analysis of dark matter simplified models (DMSMs) with leptophobic mediator particles of spin one, considering the cases of both vector and axial-vector interactions with dark matter (DM) particles and quarks. We require the DMSMs to provide all the cosmological DM density indicated by Planck and other observations, and we impose the upper limits on spin-independent and -dependent scattering from direct DM search experiments. We also impose all relevant LHC constraints from searches for monojet events and measurements of the dijet mass spectrum. We model the likelihood functions for all the constraints and combine them within the MasterCode framework, and probe the full DMSM parameter spaces by scanning over the mediator and DM masses and couplings, not fixing any of the model parameters. We find, in general, two allowed regions of the parameter spaces: one in which the mediator couplings to Standard Model (SM) and DM particles may be comparable to those in the SM and the cosmological DM density is reached via resonant annihilation, and one in which the mediator couplings to quarks are $\lesssim 10^{-3}$ and DM annihilation is non-resonant. We find that the DM and mediator masses may well lie within the ranges accessible to LHC experiments. We also present predictions for spin-independent and -dependent DM scattering, and present specific results for ranges of the DM couplings that may be favoured in ultraviolet completions of the DMSMs.

    hep-phastro-ph.HEhep-exEPJC(2019)·23 citations
17. 17*

    Dark matter and bubble nucleation in old neutron stars

    A. Herrero🇪🇸 · M. A. Pérez-García🇪🇸 · J. Silk🇫🇷 · C. Albertus🇪🇸

    We study the probability for nucleation of quark matter droplets in the dense cold cores of old neutron stars induced by the presence of a self-annihilating dark matter component, $\chi$. Using a parameterized form of the equation of state for hadronic and quark phases of ordinary matter, we explore the thermodynamic conditions under which droplet formation is facilitated by the energy injection from $\chi$ self-annihilations. We obtain the droplet nucleation time as a function of the dark matter candidate mass, $m_{\chi }$. We discuss further observational consequences.

    hep-phastro-ph.HEnucl-thPRD(2019)·24 citations
18. 18*

    Resonance enhancement of Charm CP

    Amarjit Soni🇺🇸

    It is suggested that a nearby $0^{++}$ resonance, $f_0$(1710) of mass $m_f=1723MeV$ and width $\Gamma =139$ MeV is playing a significant role in efficiently providing the strong (CP-conserving) and weak (CP-odd) phase simultaneously in the recently observed direct CP asymmetry $\Delta A_{CP}$ by the LHCb collaboration. The direct CP arises by the well known penguin-tree interference wherein the virtual b-quark in the c-u penguin is the source of the Kobayashi-Maskawa CP-odd phase, $\gamma$, in the SM. Loop (penguin) corrections generate left-right operators enhancing coupling to the $0^{++}$ scalar resonance. The scalar resonance is likely rich in gluonic content perhaps leading to a better understanding of large breaking of flavor SU(3) that has been known for a long-time. Approximate calculations give a rough understanding of the observed size of the CP asymmetry. The mechanism leads to several interesting implications which can be experimentally studied and tested. Moreover, in an analogous fashion to $f_0$, 4-quark operators also generate $P\times P$, P being a pseudo-scalar bilinear, which may be dominated by the nearby $\eta (1760)$ of width about 250 MeV that can influence final states such as 4 $\pi$'s, ${\eta }^{\prime }(\eta )+{\pi }^{+}+{\pi }^{-}$ etc which could exhibit CP violating triple correlation or energy asymmetries. We also briefly discuss CP violation in radiative charm decays and suggest that simple final states $\gamma \rho$ and $\gamma \varphi$ are best suited for sizeable asymmetries as well as providing precise tests of the SM.

    hep-phhep-exhep-lat45 citations
19. 19*

    Mapping the shape of the scalar potential with gravitational waves

    Mikael Chala🇬🇧 · Valentin V. Khoze🇬🇧 · Michael Spannowsky🇬🇧 · Philip Waite🇬🇧

    We study the dependence of the observable stochastic gravitational wave background induced by a first-order phase transition on the global properties of the scalar effective potential in particle physics. The scalar potential can be that of the Standard Model Higgs field, or more generally of any scalar field responsible for a spontaneous symmetry breaking in beyond-the-Standard-Model settings thatprovide for a first-order phase transition in the early universe.Characteristics of the effective potential include the relative depth of the true minimum ($E_{\alpha }^4$), the height of the barrier that separates it from the false one ($E_m^4$) and the separation between the two minima in field space ($v$), all at the bubble nucleation temperature. We focus on a simple yet quite general class of single-field polynomial potentials, with parameters being varied over several orders of magnitude. It is then shown that gravitational wave observatories such as aLIGO O5, BBO, DECIGO and LISA are mostly sensitive to values of these parameters in the region $E_{\alpha }\sim (0.1-10)\times E_m$. Finally, relying on well-defined models and using our framework, we demonstrate how to obtain the gravitational wave spectra for potentials of various shapes without necessarily relying on dedicated software packages.

    hep-phInt.J.Mod.Phys.A(2019)·22 citations
20. 20*

    Radiative corrections of order O(alpha E_e/m_N) to Sirlin's radiative corrections of order O(alpha/pi) to neutron lifetime

    A. N. Ivanov🇦🇹 · R. Höllwieser🇦🇹 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

    We calculate the radiative corrections of order O(alpha E_e/m_N) as next-to-leading order corrections in the large nucleon mass expansion to Sirlin's radiative corrections of order O(alpha/pi) to the neutron lifetime. The calculation is carried out within a quantum field theoretic model of strong low-energy pion--nucleon interactions described by the linear sigma-model (LsM) with chiral SU(2)xSU(2) symmetry and electroweak hadron-hadron, hadron-lepton and lepton-lepton interactions for the electron-lepton family with SU(2)_L x U(1)_Y symmetry of the Standard Electroweak Model (SEM). Such a quantum field theoretic model is some kind a hadronized version of the Standard Model (SM). From a gauge invariant set of the Feynman diagrams with one-photon exchanges we reproduce Sirlin's radiative corrections of order O(alpha/pi), calculated to leading order in the large nucleon mass expansion, and calculate next-to-leading corrections of order O(alpha E_e/m_N). This confirms Sirlin's confidence level of the radiative corrections O(alpha E_e/m_N). The contributions of the LsM are taken in the limit of the infinite mass of the scalar isoscalar sigma-meson. In such a limit the LsM reproduces the results of the current algebra (Weinberg, Phys. Rev. Lett. {\bf 18}, 188 (1967)) in the form of effective chiral Lagrangians of pion-nucleon interactions with non--linear realization of chiral SU(2)xSU(2) symmetry. In such a limit the L$\sigma$M is also equivalent to Gasser-Leutwyler's chiral quantum field theory or chiral perturbation theory (ChPT) with chiral SU(2)xSU(2)symmetry and the exponential parametrization of a pion-field (Ecker, Prog. Part. Nucl. Phys. {\bf 35}, 1 (1995)).

    hep-phhep-exnucl-exPRD(2019)·9 citations
21. 21*

    The Muon $g-2$ experiment at Fermilab

    Alexander Keshavarzi🇺🇸

    The current $\sim 3.5\sigma$ discrepancy between the experimental measurement and theoretical prediction of the muon magnetic anomaly, $a_{\mu }$, stands as a potential indication of the existence of new physics. The Muon $g-2$ experiment at Fermilab is set to measure $a_{\mu }$ with a four-fold improvement in the uncertainty with respect to previous experiment, with an aim to determine whether the $g-2$ discrepancy is well established. The experiment recently completed its first physics run and a summer programme of essential upgrades, before continuing on with its experimental programme. The Run-1 data alone are expected to yield a statistical uncertainty of 350 ppb and the publication of the first result is expected in late-2019.

    ↳ hep-exhep-phEPJ Web Conf.(2019)·26 citations
22. 22*

    Cosmic Microwave Background constraints on non-minimal couplings in inflationary models with power law potentials

    Mehdi Shokri🇮🇹 · Fabrizio Renzi🇮🇹 · Alessandro Melchiorri🇮🇹

    Inflationary models with power-law potentials are starting to be severely constrained by the recent measurements of Cosmic Microwave Background anisotropies provided by the Planck Satellite and by the BICEP2 telescope. In particular, models with power-law potentials $V(\phi )\propto {\phi }^n$ with $n\ge 2$ are strongly disfavored by present data since they predict a sizable contribution of gravitational waves with a tensor/scalar ratio of $r\sim 0.15$ that is at odds with current limits. A non-minimal coupling to gravity has been proposed as a physical mechanism to lower the predictions for $r$. In this paper we further investigate the issue, presenting constraints on non-minimal couplings from current CMB data under the assumption of power-law potentials. We found that models with $n>2$ show a statistically significant indication (above $95\%$ C.L.) for a non minimal coupling. Non minimal coupling is also preferred by models with $n<2$ albeit just at about $68\%$ C.L.. Interestingly, all the models considered show a non-zero running of the spectral index, $n_{\mathrm{run}}$, consistent with the 2018 Planck release value of $-0.007\pm 0.0068$. We point out how future accurate measurement of $n_{\mathrm{run}}$ would be necessary to significantly constraint these models and eventually rule out some or all of them. The combination of Planck data with the Bicep/Keck dataset strengthen these considerations.

    ↳ astro-ph.COhep-phPhys.Dark Univ.(2019)·21 citations
23. 23*

    Net-proton number fluctuations in the presence of the QCD critical point

    Michał Szymański🇵🇱 · Marcus Bluhm🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    Event-by-event fluctuations of the net-proton number studied in heavy-ion collisions provide an important means in the search for the conjectured critical end point (CP) in the QCD phase diagram. We propose a phenomenological model in which the fluctuations of the chiral critical mode couple to protons and anti-protons. This allows us to study the behavior of the net-proton number fluctuations in the presence of the CP. Calculating the net-proton number cumulants, $C_n$ with n=1,2,3,4, along the phenomenological freeze-out line we show that the ratio of variance and mean $C_2/C_1$, as well as kurtosis $C_4/C_2$ resemble qualitative properties observed in data in heavy-ion collisions as a function of beam energy obtained by the STAR Collaboration at RHIC. In particular, the non-monotonic structure of the kurtosis and smooth change of the $C_2/C_1$ ratio with beam energy could be due to the CP located near the freeze-out line. The skewness, however, exhibits properties that are in contrast to the criticality expected due to the CP. The dependence of our results on the model parameters and the proximity of the chemical freeze-out to the critical point are also discussed.

    ↳ nucl-thhep-phJ.Phys.G(2020)·12 citations
24. 24*

    Topology change from a monopole to a dipole in Berry's phase

    Shinichi Deguchi🇯🇵 · Kazuo Fujikawa🇯🇵

    The smooth topology change of Berry's phase from a Dirac monopole-like configuration to a dipole configuration, when one approaches the monopole position in the parameter space, is analyzed in an exactly solvable model. A novel aspect of Berry's connection ${\mathcal{A}}_k$ is that the geometrical center of the monopole-like configuration and the origin of the Dirac string are displaced in the parameter space. Gauss' theorem ${\int }_S(\nabla \times \mathcal{A})\cdot d\vec{S}={\int }_V\nabla \cdot (\nabla \times \mathcal{A})dV=0$ for a volume $V$ which is free of singularities shows that a combination of the monopole-like configuration and the Dirac string is effectively a dipole. The smooth topology change from a dipole to a monopole with a quantized magnetic charge $e_M=2\pi \hslash$ takes place when one regards the Dirac string as unobservable if it satisfies the Wu-Yang gauge invariance condition. In the transitional region from a dipole to a monopole, a half-monopole appears with an observable Dirac string, which is analogous to the Aharonov-Bohm phase of an electron for the magnetic flux generated by the Cooper pair condensation. The main topological features of an exactly solvable model are shown to be supported by a generic model of Berry's phase.

    ↳ hep-thcond-mat.mes-hallhep-phPRD(2019)·6 citations
25. 25*

    A microscopic model for inflation from supersymmetry breaking

    Ignatios Antoniadis🇫🇷 · Auttakit Chatrabhuti🇹🇭 · Hiroshi Isono🇹🇭 · Rob Knoops🇹🇭

    We have proposed recently a framework for inflation driven by supersymmetry breaking with the inflaton being a superpartner of the goldstino, that avoids the main problems of supergravity inflation, allowing for: naturally small slow-roll parameters, small field initial conditions, absence of a (pseudo)scalar companion of the inflation, and a nearby minimum with tuneable cosmological constant. It contains a chiral multiplet charged under a gauged R-symmetry which is restored at the maximum of the scalar potential with a plateau where inflation takes place. The effective field theory relies on two phenomenological parameters corresponding to corrections to the Kähler potential up to second order around the origin. The first guarantees the maximum at the origin and the second allows the tuning of the vacuum energy between the F- and D-term contributions. Here, we provide a microscopic model leading to the required effective theory. It is a Fayet-Iliopoulos model with two charged chiral multiplets under a second U(1) R-symmetry coupled to supergravity. In the Brout-Englert-Higgs phase of this U(1), the gauge field becomes massive and can be integrated out in the limit of small supersymmetry breaking scale. In this work, we perform this integration and we show that there is a region of parameter space where the effective supergravity realises our proposal of small field inflation from supersymmetry breaking consistently with observations and with a minimum of tuneable energy that can describe the present phase of our Universe.

    ↳ hep-thhep-phEPJC(2019)·14 citations
26. 26*

    Results and techniques for higher order calculations within the gradient-flow formalism

    Johannes Artz🇩🇪 · Robert V. Harlander🇩🇪 · Fabian Lange🇩🇪 · Tobias Neumann🇺🇸 · Mario Prausa🇩🇪

    We describe in detail the implementation of a systematic perturbative approach to observables in the QCD gradient-flow formalism. This includes a collection of all relevant Feynman rules of the five-dimensional field theory and the composite operators considered in this paper. Tools from standard perturbative calculations are used to obtain Green's functions at finite flow time $t$ at higher orders in perturbation theory. The three-loop results for the quark condensate at finite $t$ and the conversion factor for the "ringed" quark fields to the $\overline{\text{mbox}MS}$ scheme are presented as applications. We also re-evaluate an earlier result for the three-loop gluon condensate, improving on its accuracy.

    ↳ hep-lathep-phJHEP(2019)·62 citations
27. 27*

    Gravitational waves from first-order phase transitions: Ultra-supercooled transitions and the fate of relativistic shocks

    Ryusuke Jinno🇩🇪 · Hyeonseok Seong🇰🇷 · Masahiro Takimoto🇮🇱 · Choong Min Um🇯🇵

    We study the gravitational wave (GW) production in extremely strong first order phase transitions where the latent heat density dominates the plasma energy density, $\alpha \gtrsim 1$. In such transitions, bubbles develop extremely thin and relativistic fluid configurations, resulting in strong shock waves after collisions. We first propose a strategy to understand the GW production in such a system by separating the problem into the propagation part and the collision part. Focusing on the former, we next develop an effective theory for the propagation of the relativistic fluid shells. Using this effective theory, we finally calculate the expected duration of the relativistic fluid configurations and discuss its implications to the GW production.

    ↳ astro-ph.COgr-qchep-phphysics.flu-dynJCAP(2019)·63 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.