Mon·Dec 3, 2018Monday·December 3, 2018

1. 01*

   Extended Higgs sector of 2HDM with real singlet facing LHC data

   A. Arhrib🇲🇦 · R. Benbrik🇲🇦 · M. EL Kacimi🇲🇦 · L. Rahili🇲🇦 · S. Semlali🇲🇦

   We study the phenomenology of the two Higgs doublet model with a real singlet scalar $S$ (2HDMS). The model predicts three CP-even Higgses $h_{1,2,3}$, one CP-odd $A^0$ and a pair of charged Higgs. We discuss the consistency of the 2HDMS with theoretical as well as with all available experimental data. In contrast with previous studies, we focus on the scenario where $h_2$ is the Standard Model (SM) 125 GeV Higgs, while $h_1$ is lighter than $h_2$ which may open a window for Higgs to Higgs decays. We perform an extensive scan into the parameter space of 2HDMS of type I and explore the effect of the singlet-doublet admixture. We found that a large singlet-doublet admixture is still compatible with the recent Higgs data from LHC. Moreover, we show that $h_1$ could be quasi-fermiophobic and would decay dominantly into two photons. We also study in details the consistency of the non-detected decay of $h_2\to h_1{h}_1$ with LHC data followed by $h_1\to \gamma \gamma$ which leads to four photons final state at LHC: $pp\to h_2\to h_1{h}_1\to 4\gamma$. Using the results of null searches of multi-photons carried by the ATLAS collaboration, we have found that a large area of the parameter space is still allowed. We also demonstrate that various neutral Higgs of the 2HDMS could have several exotic decays.

   hep-phEPJC(2020)·30 citations
2. 02*

   Direct Detection Experiments at the Neutrino Dipole Portal Frontier

   Ian M. Shoemaker🇺🇸 · Jason Wyenberg🇺🇸

   Heavy sterile neutrinos are typically invoked to accommodate the observed neutrino masses, by positing a new Yukawa term connecting these new states to the neutrinos in the electroweak doublet. However, given our ignorance of the neutrino sector we should explore additional interactions such sterile neutrinos may have with the SM. In this paper, we study the dimension-5 operator which couples the heavy state to a light neutrino and the photon. We find that the recent XENON1T direct detection data can improve the limits on this "Neutrino Dipole Portal" by up to an order of magnitude over previous bounds. Future direct detection experiments may be able to extend these bounds down to the level probed by SN1987A.

   hep-phhep-exPRD(2019)·60 citations
3. 03*

   Constraints on $U(1{)}_{L_{\mu }-L_{\tau }}$ from LHC Data

   Manuel Drees🇩🇪 · Meng Shi🇩🇪 · Zhongyi Zhang🇩🇪

   In this study, we apply LHC data to constrain the extension of the Standard Model by an anomaly-free $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge group; this model contains a new gauge boson ($Z^{\prime }$) and a scalar dark matter particle (${\varphi }_{\mathrm{DM}}$). We recast a large number of LHC analyses from ATLAS and CMS of multi-lepton final states. We find that for $10$ GeV $<m_{Z^{\prime }}<60$ GeV the strongest constraint comes from a dedicated $Z^{\prime }$ search in the $4\mu$ final state by the CMS collaboration; for larger $Z^{\prime }$ masses, searches for final states with three leptons plus missing $E_T$ are more sensitive. Searches for final states with two leptons and missing $E_T$, which are sensitive to $Z^{\prime }$ decays into dark matter particles, can only probe regions of parameter space that are excluded by searches in the $3$ and $4$ lepton channels. The combination of LHC data excludes values of $Z^{\prime }$ mass and coupling constant that can explain the deficit in $g_{\mu }-2$ for $4$ GeV $\le m_{Z^{\prime }}\le 500$ GeV. However, for much of this range the LHC bound is weaker than the bound that can be derived from searches for trident events in neutrino-nucleus scattering.

   hep-phhep-exPLB(2019)·22 citations
4. 04*

   First results on the scalar WIMP-pion coupling, using the XENON1T experiment

   E. Aprile🇺🇸 · J. Aalbers🇳🇱 · F. Agostini🇮🇹 · M. Alfonsi🇩🇪 · L. Althueser🇩🇪 · F. D. Amaro🇵🇹 · M. Anthony🇺🇸 · V. C. Antochi🇸🇪 · F. Arneodo🇦🇪 · L. Baudis🇨🇭 · B. Bauermeister🇸🇪 · M. L. Benabderrahmane🇦🇪 and 120 other authors

   We present first results on the scalar WIMP-pion coupling from 1 t$\times$yr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most non-relativistic operators, these pion-exchange currents can be coherently enhanced by the total number of nucleons, and therefore may dominate in scenarios where spin-independent WIMP-nucleon interactions are suppressed. Moreover, for natural values of the couplings, they dominate over the spin-dependent channel due to their coherence in the nucleus. Using the signal model of this new WIMP-pion channel, no significant excess is found, leading to an upper limit cross section of $6.4\times 10^{-46}$ cm${}^2$ (90 % confidence level) at 30 GeV/c${}^2$ WIMP mass.

   hep-phastro-ph.COhep-exnucl-thPRL(2019)·53 citations
5. 05*

   FASER's Physics Reach for Long-Lived Particles

   FASER Collaboration: Akitaka Ariga🇨🇭 · Tomoko Ariga🇯🇵 · Jamie Boyd🇨🇭 · Franck Cadoux🇨🇭 · David W. Casper🇺🇸 · Yannick Favre🇨🇭 · Jonathan L. Feng🇺🇸 · Didier Ferrere🇨🇭 · Iftah Galon🇺🇸 · Sergio Gonzalez-Sevilla🇨🇭 · Shih-Chieh Hsu🇺🇸 · Giuseppe Iacobucci🇨🇭 and 15 other authors

   FASER,the ForwArd Search ExpeRiment,is a proposed experiment dedicated to searching for light, extremely weakly-interacting particles at the LHC. Such particles may be produced in the LHC's high-energy collisions and travel long distances through concrete and rock without interacting. They may then decay to visible particles in FASER, which is placed 480 m downstream of the ATLAS interaction point. In this work we briefly describe the FASER detector layout and the status of potential backgrounds. We then present the sensitivity reach for FASER for a large number of long-lived particle models, updating previous results to a uniform set of detector assumptions, and analyzing new models. In particular, we consider all of the renormalizable portal interactions, leading to dark photons, dark Higgs bosons, and heavy neutral leptons (HNLs); light B-L and $L_i-L_j$ gauge bosons; axion-like particles (ALPs) that are coupled dominantly to photons, fermions, and gluons through non-renormalizable operators; and pseudoscalars with Yukawa-like couplings. We find that FASER and its follow-up, FASER 2, have a full physics program, with discovery sensitivity in all of these models and potentially far-reaching implications for particle physics and cosmology.

   hep-phhep-exPRD(2019)·461 citations
6. 06*

   BRST invariant $d=2$ condensates in Gribov-Zwanziger theory

   David Dudal🇧🇪 · Caroline Felix🇧🇪 · Leticia Palhares🇧🇷 · François Rondeau🇫🇷 · David Vercauteren🇻🇳

   In this proceeding, $SU(N)$ Yang-Mills theory is quantized in the linear covariant gauges, while taking into account the issue of Gribov copies and we construct the one-loop effective potential for a set of mass dimension 2 condensates, including the Gribov parameter, that refines the infrared region of the Gribov-Zwanziger theory, whilst respecting renormalization group invariance and BRST symmetry.

   hep-phhep-thPoS(2019)·1 citation
7. 07*

   Multicomponent Superfluids and Superconductors in Dense Nuclear and Quark Matter

   Alexander Haber🇦🇹

   Matter at intermediate baryon densities and low temperatures is notoriously hard to tackle theoretically. Whereas lattice methods cannot cover more than rather small densities, perturbative methods are only applicable at much higher densities. The regime of intermediate chemical potential at low temperatures in the QCD-phase diagram is therefore out of reach of first-principle methods, thus we have to rely on stellar objects to investigate dense nuclear and quark matter at low temperatures. Compact stars can serve as an unique laboratory for this regime. Due to their fast rotation and high magnetic field, phenomena like hydrodynamic instabilities and the formation of vortices/flux tubes become of phenomenological interest. In my thesis, I investigate these multicomponent systems in a consistent multi-fluid treatment. By starting from a fieldtheoretical, bosonic model, the phase structure of a two-fluid system, e.g. consisting of superfluid neutrons and superconducting protons, is explored. Consequently, hydrodynamic instabilities, which might serve as trigger for pulsar glitches, are calculated for these two-fluid systems. By incorporating a gauge field and taking into account the charge of one scalar field, the influence of a superfluid on the magnetic phase structure of a superconductor is studied. In the last part, color superconducting quark matter, which can effectively be described as a multicomponent (color-)supercondcutor, is investigated.

   hep-phnucl-th2 citations
8. 08*

   An analytical approach to the field amplification and particle production by parametric resonance during inflation and reheating

   Tao Zhu🇨🇳 · Qiang Wu🇨🇳 · Anzhong Wang🇺🇸

   Field amplification and particle production due to parametric resonance are highly nontrivial predictions of quantum fields that couple to an oscillating source during inflation and reheating. Understanding this two effects is crucial for the connection between the resonance phenomenon and precise observational data. In this paper, we give a general and analytic analysis of parametric resonance of relevant field modes evolving during inflation and reheating by using the uniform asymptotic approximation. This analysis can provide a clear and quantitative explanation for the field amplification and particle production during the resonance. The potential applications of our results to several examples, including sound resonance during inflation, particle productions during reheating, and parametric resonance due to self-resonance potentials, have also been explored. The formalism developed in this paper is also applicable to parametric resonance in a broad areas of modern science.

   hep-phgr-qchep-thPhys.Dark Univ.(2019)·21 citations
9. 09*

   Light Sterile Neutrino and Low Scale Left-Right Symmetry in D-brane inspired $SU(4{)}_C\times SU(2{)}_L\times SU(2{)}_R$

   George K. Leontaris🇬🇷 · Qaisar Shafi🇺🇸

   Motivated by the ongoing searches for new physics at the LHC, we explore the low energy consequences of a D-brane inspired $SU(4{)}_C\times SU(2{)}_L\times SU(2{)}_R$ (4-2-2) model. The Higgs sector consists of an $SU(4)$ adjoint, a pair $H+\bar{H}$ in $(4,1,2)+(\bar{4},1,2)$, and a bidoublet field in $h(1,2,2)$. With the $SU(4)$ adjoint the symmetry breaks to a left-right symmetric $SU(3{)}_C\times U(1{)}_{B-L}\times SU(2{)}_L\times SU(2{)}_R$ model. A missing partner mechanism protects the $SU(2{)}_R$ Higgs doublets in $H,\bar{H}$, which subsequently break the symmetry to the Standard Model at a few TeV scale. An inverse seesaw mechanism generates masses for the observed neutrinos and also yields a sterile neutrino which can play the rôle of dark matter if its mass lies in the keV range. Other phenomenological implications including proton decay are briefly discussed.

   hep-phPRD(2019)·2 citations
10. 10*

    Gaugino Mediation Scenarios for Muon $g-2$ and Dark Matter

    Peter Cox🇯🇵 · Chengcheng Han🇯🇵 · Tsutomu T. Yanagida🇯🇵 · Norimi Yokozaki🇯🇵

    We explore the possibility that the muon $g-2$ anomaly and the nature of dark matter can be simultaneously explained within the framework of gaugino mediation, focusing on bino-like dark matter where the observed abundance is obtained via co-annihilations. The minimal model with non-universal gaugino masses is excluded by stau vacuum instability, although this constraint can be somewhat relaxed via the addition of a universal soft scalar mass (or $B-L$ gaugino mediation). A more promising alternative is gaugino+Higgs mediation, which significantly raises the soft masses of the third generation sfermions leading to a split spectrum. In this framework, the muon $g-2$ can be easily explained and the dark matter abundance obtained through either bino-wino or bino-slepton co-annihilations.

    hep-phJHEP(2019)·25 citations
11. 11*

    Searching for the Odderon in Ultraperipheral Proton--Ion Collisions at the LHC

    L.A. Harland-Lang🇬🇧 · V.A. Khoze🇬🇧 · A.D. Martin🇬🇧 · M.G. Ryskin🇬🇧

    We explore the possibility of observing Odderon exchange in proton--ion collisions at the LHC, via the ultraperipheral photoproduction of C-even mesons. As well as the signal, we consider in detail the principle backgrounds, due to QCD--initiated production (i.e. double Pomeron exchange) and $\gamma \gamma$ fusion. We find that while the photon--initiated background is dominant at very small momentum transfer, this can be effectively removed by placing a reasonable cut on the transverse momentum of the produced meson. In the case of QCD--initiated production, we show this is in general strongly suppressed by the small probability of no additional particle production in the central detector, namely the survival factor. In some scenarios, this suppression is sufficient to permit the observation of Odderon exchange in Pb$-p$ collisions in a clean environment, or else to place bounds on this. We in addition identify the cases of ${\pi }^0$ and $\eta (548)$ production as particularly promising channels. Here, the QCD--initiated background is absent for ${\pi }^0$ due to isospin conservation and very small for $\eta (548)$ due to its dominantly flavour octet nature and odd parity.

    hep-phPRD(2019)·24 citations
12. 12*

    SuperIso Relic new extensions for direct and indirect detection

    G. Robbins🇪🇪 · A. Arbey🇫🇷 · F. Mahmoudi🇫🇷

    SuperIso Relic is a public computing program for the calculation of flavour observables and relic density in supersymmetry (MSSM and NMSSM). We present new extensions of the code dedicated to the calculation of dark matter direct and indirect detection constraints from the latest experimental results. Contrary to most of the existing programs, this new version allows the user to consider straightforwardly the uncertainties related to nuclear form factors, dark matter density and velocity, as well as cosmic-ray propagation through the galactic medium. The user thus finds a direct way to calculate "conservative", "standard" or "stringent" constraints according to the chosen set of uncertainties. Some examplified results showing the impact of such uncertainties are also presented.

    hep-phPoS(2019)·0 citations
13. 13*

    Isovector scalar $a_0(980)$ and $a_0(1450)$ resonances in the $B\to \psi (K\bar{K},\pi \eta )$ decays

    Zhou Rui🇨🇳 · Ya-Qian Li🇨🇳 · Jie Zhang🇨🇳

    We present an analysis of two isovector scalar resonant contributions to the $B$ decays into charmonia plus $K\bar{K}$ or $\pi \eta$ pair in the perturbative QCD approach. The Flatté model for the $a_0(980)$ resonance and the Breit Wigner formula for the $a_0(1450)$ resonance are adopted to parametrize the timelike form factors in the dimeson distribution amplitudes, which capture the important final state interactions in these processes. The predicted distribution in the $K^{+}{K}^{-}$ invariant mass as well as its integrated branching ratio for the $a_0(980)$ resonance in the $B^0\to J/\psi K^{+}{K}^{-}$ mode agree well with the current available experimental data. The obtained branching ratio of the quasi-two-body decay $B^0\to J/\psi a_0(980)(\to {\pi }^0\eta )$ can reach the order of $10^{-6}$, letting the corresponding measurement appear feasible. For the $a_0(1450)$ component, our results could be tested by further experiments in the LHCb and Belle II. We also discuss some theoretical uncertainties in detail in our calculation.

    hep-phPRD(2019)·23 citations
14. 14*

    Dark matter and the early Universe

    A. Arbey🇫🇷 · J. Ellis🇬🇧 · F. Mahmoudi🇫🇷 · G. Robbins🇫🇷

    Big-Bang nucleosynthesis (BBN) represents one of the earliest phenomena that can lead to observational constraints on the early Universe properties. It is well-known that many important mechanisms and phase transitions occurred before BBN. We discuss the possibility of gaining insight into the primordial Universe through studies of dark matter in cosmology, astroparticle physics and colliders. For this purpose, we assume that dark matter is a thermal relic, and show that combining collider searches with dark matter observables can lead to strong constraints on the period of freeze-out before BBN.

    hep-phastro-ph.COPoS(2019)·2 citations
15. 15*

    Status of the (p)MSSM Higgs sector

    A. Arbey🇫🇷 · M. Battaglia🇨🇭 · A. Djouadi🇫🇷 · F. Mahmoudi🇫🇷 · M. Muehlleitner🇩🇪 · G. Robbins🇫🇷 · M. Spira🇨🇭

    We present some highlights on the complementaries of the Higgs and SUSY searches at the LHC, using the 8 and 13 TeV results. In particular, we discuss the constraints that can be obtained on the MSSM parameters by the determination of the Higgs boson mass and couplings. In addition, we investigate the interplay with heavy Higgs searches, and evaluate how higher LHC luminosities and a future linear collider can help probing the pMSSM Higgs sector and reconstructing the underlying parameters.

    hep-phPoS(2019)·2 citations
16. 16*

    Phenomenological consequences of Higgs inflation in the NMSSM at the electroweak scale

    Wolfgang Gregor Hollik🇩🇪 · Stefan Liebler🇩🇪 · Gudrid Moortgat-Pick🇩🇪 · Sebastian Paßehr🇫🇷 · Georg Weiglein🇩🇪

    The Next-to-Minimal Supersymmetric Standard Model (NMSSM) can incorporate inflation, where a combination of the Higgs-doublet fields plays the role of the inflaton. At the high scale, the Higgs doublets are non-minimally coupled to supergravity; this coupling appears as an additional contribution to the $\mu$ term in the low-energy effective superpotential and potentially changes physics at the electroweak scale. In a recent publication, we investigate the extended parameter space of this model with respect to collider phenomenology at the electroweak scale, and discuss scenarios which are potentially different from the pure NMSSM. We analyse the stability of the electroweak vacuum, the masses of neutralinos/charginos and Higgs bosons as well as the mixing and decays of Higgs bosons. Some important aspects of this study are described in the following.

    hep-phPoS(2019)·1 citation
17. 17*

    $B_s$-${\bar{B}}_s$ mixing interplay with $B$ anomalies

    Luca Di Luzio🇮🇹 · Matthew Kirk🇬🇧 · Alexander Lenz🇬🇧

    After reviewing the theoretical uncertainties entering the Standard Model determination of the mass difference of the neutral $B_s$-${\bar{B}}_s$ meson system, $\Delta M_s^{\mathrm{SM}}$, we discuss the implications of its updated value for new physics models addressing the experimental anomalies in semi-leptonic $B$ decays. Using the most recent FLAG average of lattice results for the non-perturbative matrix elements and the CKM-fitter determination of $V_{cb}$ points to a $1.8\sigma$ discrepancy in $\Delta M_s^{\mathrm{SM}}>\Delta M_s^{\exp }$. Extending the analysis in Ref. [1] we show that the latter tension cannot be easily accommodated within single mediator models, whenever the same mediator is also responsible for the $b\to s\ell \ell$ anomalies.

    hep-ph14 citations
18. 18*

    Dynamical spin effects within the pseudo scalar nonet within holographic QCD

    Mohammad Ahmady🇨🇦 · Chandan Mondal🇨🇳 · Ruben Sandapen🇨🇦

    We investigate the importance of dynamical spin effects in the holographic light-front wavefunctions of the pseudoscalar mesons. We find that these effects are crucial to describe the pion data while they are not necessary to describe the available kaon data. For $\eta -{\eta }^{\prime }$ system, we find that dynamical spin effects are required to describe their transition form factors data.

    hep-phPoS(2018)·0 citations
19. 19*

    Exclusive heavy quark-pair production in ultraperipheral collisions

    Mateus Reinke Pelicer🇧🇷 · Emmanuel G. de Oliveira🇧🇷 · Roman Pasechnik🇸🇪

    In this article, we study the fully differential observables of exclusive production of heavy (charm and bottom) quark pairs in high-energy ultraperipheral $pA$ and $AA$ collisions. In these processes, the nucleus $A$ serves as an efficient source of the photon flux, while the QCD interaction of the produced heavy-quark pair with the target ($p$ or $A$) proceeds via an exchange of gluons in a color singlet state, described by the gluon Wigner distribution. The corresponding predictions for differential cross sections were obtained by using the dipole $S$-matrix in the McLerran--Venugopalan saturation model with impact parameter dependence for the nucleus target, and its recent generalization, for the proton target. Prospects of experimental constraints on the gluon Wigner distribution in this class of reactions are discussed.

    hep-phPRD(2019)·14 citations
20. 20*

    QCD strings and the U(1) problem

    Chi Xiong🇸🇬

    We promote the usual QCD $\theta$-parameter to a field and interpret it as the phase of the quark condensate, which becomes nontrivial when topological defects, vortices in our formulation, are induced in the quark condensate by the QCD strings (chromoelectric flux tubes). The QCD topological term emerges naturally as a derivative coupling between the Chern-Simons current and a supercurrent in the quark condensate. This new formulation can address the $U_A(1)$ problem and leads to the chiral magnetic effects. It is possible that in this formulation the strong CP problem can be avoided without the axion particle.

    hep-phEPJ Web Conf.(2019)·1 citation
21. 21*

    Light vector mesons ($\omega$, $\rho$ and $\varphi$) in strong magnetic fields: A QCD sum rule approach

    Amruta Mishra🇮🇳 · Ankit Kumar🇮🇳 · Pallabi Parui🇮🇳 · Sourodeep De🇮🇳

    The mass modifications of the light vector mesons ($\omega$, $\rho$ and $\varphi$) are investigated in asymmetric nuclear matter in the presence of strong magnetic fields, using a QCD sum rule approach. These are computed from the medium modifications of the non-strange and strange light quark condensates as well as scalar gluon condensate. The quark and gluon condensates are calculated from the medium changes of the scalar fields (non-strange and strange) and a scalar dilaton field in the magnetized nuclear matter, within a chiral SU(3) model. The scalar dilaton field within the model breaks the scale invariance of QCD and simulates the gluon condensate. The anomalous magnetic moments for the nucleons are taken into account in the present study.

    ↳ nucl-thhep-phPRC(2019)·17 citations
22. 22*

    Evolution of high-energy particle distribution in Supernova Remnants

    Houdun Zeng🇨🇳 · Yuliang Xin🇨🇳 · Siming Liu🇨🇳

    Supernova remnants (SNRs) have been considered as the dominant contributors to Galactic cosmic rays. However, the relation between high-energy particles trapped in SNRs and cosmic rays observed at the Earth remains obscure. In this paper, we fit the spectral energy distributions of 35 SNRs with a simple one-zone emission model and analyze correlations of model parameters to uncover the evolution of high-energy particle distribution in SNRs. We find that (1) the particle distribution in general can be described by a broken power-law function with a high-energy cutoff for all SNRs; (2) the low-energy spectrum becomes harder and the break energy decreases with aging of SNRs, (3) for most middle-age SNRs, the energy loss timescale of electrons at the high-energy cutoff is approximately equal to the age of the corresponding remnant implying quenching of very high-energy electron acceleration; for young SNRs, this energy loss timescale is shorter than the age of SNRs implying continuous electon acceleration at the cutoff energy; and for a few old age SNRs, the energy loss timescale is longer than the corresponding age which may suggest escaping of higher energy particles from SNRs. Finally, we comment on the implications of these results on the SNR origin of Galactic cosmic rays.

    ↳ astro-ph.HEhep-phApJ(2019)·64 citations
23. 23*

    Scaling properties of cosmological axion strings

    C. J. A. P. Martins🇵🇹

    There has been recent interest in the evolution and cosmological consequences of global axionic string networks, and in particular in the issue of whether or not these networks reach the scale-invariant scaling solution that is known to exist for the simpler Goto-Nambu and Abelian-Higgs string networks. This is relevant for determining the amount and spectrum of axions they produce. We use the canonical velocity-dependent one-scale model for cosmic defect network evolution to study the evolution of these global networks, confirming the presence of deviations to scale-invariant evolution and in agreement with the most recent numerical simulations. We also quantify the cosmological impact of these corrections and discuss how the model can be used to extrapolate the results of numerical simulations, which have a limited dynamic range, to the full cosmological evolution of the networks, enabling robust predictions of their consequences. Our analysis suggests that around the QCD scale, when the global string network is expected to disappear and produce most of the axions, the number of global strings per Hubble patch should be around $\xi \sim 4.2$, but also highlights the need for additional high-resolution numerical simulations.

    ↳ astro-ph.COhep-phhep-thPLB(2019)·51 citations
24. 24*

    Primordial gravitational waves in Horndeski gravity

    Rafael C. Nunes🇧🇷 · Marcio E. S. Alves🇧🇷 · Jose C. N. de Araujo🇧🇷

    We investigate the propagation of primordial gravitational waves within the context of the Horndeski theories, for this, we present a generalized transfer function quantifying the sub-horizon evolution of gravitational waves modes after they enter the horizon. We compare the theoretical prediction of the modified primordial gravitational waves spectral density with the aLIGO, Einstein telescope, LISA, gLISA and DECIGO sensitivity curves. Assuming reasonable and different values for the free parameters of the theory (in agreement with the event GW170817 and stability conditions of the theory), we note that the gravitational waves amplitude can vary significantly in comparison with general relativity. We find that in some cases the gravitational primordial spectrum can cross the sensitivity curves for DECIGO detector with the maximum frequency sensitivity to the theoretical predictions around 0.05 - 0.30 Hz. From our results, it is clear that the future generations of space based interferometers can bring new perspectives to probing modifications in general relativity.

    ↳ gr-qcastro-ph.COhep-phPRD(2019)·42 citations
25. 25*

    Large regular reflecting stars have no scalar field hair

    Yan Peng🇨🇳

    We investigate the gravity system constructed with static scalar fields coupled to asymptotically flat regular reflecting stars. We consider the matter field's backreaction on the reflecting star. We analytically show that there is an upper bound on the radius of the reflecting star. When the star radius is above the bound, the reflecting star cannot support the existence of scalar field hairs. That means large reflecting stars cannot have scalar field hairs.

    ↳ gr-qchep-phhep-thEPJC(2019)·8 citations
26. 26*

    Equation of state in (2+1) flavor QCD at high temperatures

    Johannes Heinrich Weber🇺🇸 · Alexei Bazavov🇺🇸 · Peter Petreczky🇺🇸

    We calculate the Equation of State at high temperatures in (2+1) flavor QCD using the highly improved staggered quark (HISQ) action. We study the lattice spacing dependence of the pressure at high temperatures using lattices with temporal extent $N_{\tau }=6,8,10$ and $12$ and perform continuum extrapolations. We also give a continuum estimate for the Equation of State up to temperatures $T=2$GeV, which are then compared with results of the weak-coupling calculations. We find reasonable agreement with the HTL calculation at the highest temperatures and a tension with the EQCD calculation of a few percent, with the lattice results in the middle between both.

    ↳ hep-lathep-phnucl-thPoS(2019)·13 citations
27. 27*

    Quartet-metric/multi-component gravity: scalar graviton as emergent dark substance

    Yury F. Pirogov🇷🇺

    In the general frameworks of an earlier introduced quartet-metric/multi-component gravity, a theory of a massive scalar graviton supplementing the massless tensor one is consistently deduced. The peculiarities of the scalar-graviton field compared to the canonical scalar one are demonstrated. The light scalar graviton is treated as an emergent dark substance of the Universe: dark matter and/or dark energy depending on the solution. The case with scalar graviton as dark energy responsible for the late-time accelerated expansion of the Universe is studied in more detail. In particular, it is shown that due to an attractor solution for the light scalar graviton there naturally emerges at the classical level a tiny nonzero effective cosmological constant, even in the absence of the Lagrangian one. The prospects of going beyond LCDM model per scalar graviton are shortly indicated.

    ↳ gr-qcastro-ph.COhep-phJCAP(2019)·6 citations
28. 28*

    Recurrent machines for likelihood-free inference

    Arthur Pesah🇸🇪 · Antoine Wehenkel🇧🇪 · Gilles Louppe🇧🇪

    Likelihood-free inference is concerned with the estimation of the parameters of a non-differentiable stochastic simulator that best reproduce real observations. In the absence of a likelihood function, most of the existing inference methods optimize the simulator parameters through a handcrafted iterative procedure that tries to make the simulated data more similar to the observations. In this work, we explore whether meta-learning can be used in the likelihood-free context, for learning automatically from data an iterative optimization procedure that would solve likelihood-free inference problems. We design a recurrent inference machine that learns a sequence of parameter updates leading to good parameter estimates, without ever specifying some explicit notion of divergence between the simulated data and the real data distributions. We demonstrate our approach on toy simulators, showing promising results both in terms of performance and robustness.

    ↳ stat.MLcs.LGhep-phphysics.data-an2 citations
29. 29*

    PEN experiment: a precise test of lepton universality

    C.J. Glaser · D. Pocanic · L.P. Alonzi · V.A. Baranov · W. Bertl · M. Bychkov · Yu.M. Bystritsky · E. Frlez · V.A. Kalinnikov · N.V. Khomutov · A.S. Korenchenko · S.M. Korenchenko and 17 other authors

    With few open channels and uncomplicated theoretical description, charged pion decays are uniquely sensitive to certain standard model (SM) symmetries, the universality of weak fermion couplings, and to aspects of pion structure and chiral dynamics. We review the current knowledge of the pion electronic decay ${\pi }^{+}\to e^{+}{\nu }_e(\gamma )$, or ${\pi }_{e2(\gamma )}$, and the resulting limits on non-SM processes. Focusing on the PEN experiment at the Paul Scherrer Institute (PSI), Switzerland, we examine the prospects for further improvement in the near term.

    ↳ hep-exhep-phnucl-ex13 citations
30. 30*

    Fermion-boson symmetry and quantum field theory

    Sau Lan Wu🇺🇸 · Tai Tsun Wu🇺🇸 · Chen Zhou🇺🇸

    The application of fermion-boson symmetry to the standard model leads to the following: first, there are three generations of scalar quarks and scalar leptons in addition to the known quarks and leptons, and, secondly, the divergences in the perturbation series for the standard model are reduced. In the light of experimental data from LEP, Tevatron Collider, and LHC, some consequences of these two statements taken together are discussed. A series of experiments are proposed to search for the scalar quarks and scalar leptons at the Large Hadron Collider. The first step in this search is to look for new fermions by analyzing events with a pair of oppositely changed leptons both with large transverse momenta. The scalar quarks and the scalar leptons are then searched for through their decays into these new fermions plus a known quark or lepton.

    ↳ physics.gen-phhep-phhep-th0 citations

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