Fri·Jun 28, 2019Friday·June 28, 2019

1. 01*

   Strong New Limits on Light Dark Matter from Neutrino Experiments

   Christopher V. Cappiello🇺🇸 · John F. Beacom🇺🇸

   The non-detection of GeV-scale WIMPs has led to increased interest in more general candidates, including sub-GeV dark matter. Direct detection experiments, despite their high sensitivity to WIMPs, are largely blind to sub-GeV dark matter. Recent work has shown that cosmic-ray elastic scattering with sub-GeV dark matter would both alter the observed cosmic ray spectra and produce a flux of relativistic dark matter, which would be detectable with traditional dark matter experiments as well as larger, higher-threshold detectors for neutrinos. Using data, detectors, and analysis techniques not previously considered, we substantially increase the regions of parameter space excluded by neutrino experiments for both dark matter-nucleon and dark matter-electron elastic scattering. We also show how to further improve sensitivity to light dark matter.

   hep-phastro-ph.HEPRD(2019)·177 citations
2. 02*

   Complete Vector-like Fourth Family and new $\mathrm{U}(1{)}^{\prime }$ for Muon Anomalies

   Junichiro Kawamura🇺🇸 · Stuart Raby🇺🇸 · Andreas Trautner🇩🇪

   We consider the Standard Model (SM) with the addition of a $\mathrm{U}(1{)}^{\prime }$ gauge symmetry and a complete fourth family of quarks and leptons which are vector-like with respect to the full $\mathrm{SU}(3{)}_{\mathrm{C}}\times \mathrm{SU}(2{)}_{\mathrm{L}}\times \mathrm{U}(1{)}_{\mathrm{Y}}\times \mathrm{U}(1{)}^{\prime }$ gauge symmetry. The model provides a unified explanation of experimental anomalies in $(g-2{)}_{\mu }$ as well as $b\to s{\ell }^{+}{\ell }^{-}$ decays. We find good fits to the deviations from the SM, while at the same time fitting all other SM observables. The model includes a new $Z^{\prime }$ gauge boson, a $\mathrm{U}(1{)}^{\prime }$-breaking scalar, and vector-like leptons all with mass of order a few $100$ GeV. It is consistent with all currently released high energy experimental data, however, it appears imminently testable with well designed future searches. Also precision flavor experiments, especially more accurate direct determinations of CKM matrix elements, would allow to probe the best fit points.

   hep-phhep-exPRD(2019)·80 citations
3. 03*

   Critical behavior of the bulk viscosity in QCD

   Mauricio Martinez🇺🇸 · Thomas Schaefer🇺🇸 · Vladimir Skokov🇺🇸

   We study the behavior of the bulk viscosity $\zeta$ in QCD near a possible critical endpoint in the phase diagram. We verify the expectation that $(\zeta /s)\sim a(\xi /{\xi }_0{)}^{x_{\zeta }}$, where $s$ is the entropy density, $\xi$ is the correlation length, ${\xi }_0$ is the non-critical correlation length, $a$ is a constant and $x_{\zeta }\simeq 3$. Using a recently developed equation of state that includes a critical point in the universality class of the Ising model we estimate the constant of proportionality $a$. We find that $a$ is typically quite small, $a\sim O(10^{-4})$. We observe, however, that the result is sensitive to the commonly made assumption that the Ising temperature axis is approximately aligned with the QCD baryon chemical potential axis. If this is not the case, then the critical $\zeta /s$ can approach the non-critical value of $\eta /s$, where $\eta$ is the shear viscosity, even if the enhancement of the correlation length is modest, $\xi /{\xi }_0\sim 2$.

   hep-phnucl-thPRD(2019)·48 citations
4. 04*

   VBSCan Thessaloniki 2018 Workshop Summary

   Riccardo Bellan🇮🇹 · Jakob Beyer🇩🇪 · Carsten Bittrich🇩🇪 · Giacomo Boldrini🇮🇹 · Ilaria Brivio🇩🇰 · Lucrezia Stella Bruni🇳🇱 · Diogo Buarque Franzosi🇸🇪 · Claude Charlot🇫🇷 · Vitaliano Ciulli🇮🇹 · Roberto Covarelli🇮🇹 · Duje Giljanovic🇭🇷 · Giulia Gonella🇩🇪 and 52 other authors

   This document reports the first year of activity of the VBSCan COST Action network, as summarised by the talks and discussions happened during the VBSCan Thessaloniki 2018 workshop. The VBSCan COST action is aiming at a consistent and coordinated study of vector-boson scattering from the phenomenological and experimental point of view, for the best exploitation of the data that will be delivered by existing and future particle colliders.

   hep-phhep-ex10 citations
5. 05*

   A New Littlest Seesaw Model

   Ping-Tao Chen🇨🇳 · Gui-Jun Ding🇨🇳 · Stephen F. King🇬🇧 · Cai-Chang Li🇨🇳

   We propose and discuss a new Littlest Seesaw model, realised in the tri-direct CP approach, in which the couplings of the two right-handed neutrinos to the lepton doublets are proportional to $(0,-1,1)$ and $(1,5/2,-1/2)$ respectively with the relative phase $\eta =-\pi /2$. This model can give an excellent description of lepton flavour mixing, including an atmospheric neutrino mixing angle in the second octant, in terms of only two input parameters. We show that the observed baryon asymmetry can be generated for the lightest right-handed neutrino mass $M_1=1.176\times 10^{11}$ GeV in SM and $M_1=3.992\times 10^{10}$ GeV in MSSM with $\tan \beta =5$. We construct an explicit Littlest Seesaw model based on the flavour symmetry $S_4\times Z_4\times Z_9$ in which the desired alignments and the phase $\eta =-\pi /2$ are achieved.

   hep-phJ.Phys.G(2020)·25 citations
6. 06*

   The infrared or ultraviolet scale for a gauge theory

   Renata Jora🇷🇴

   We propose a conjecture that leads to the determination of the intrinsic scale (the scale at which the coupling constant diverges) for any gauge theory by comparison to another theory for which there is phenomenological information, provided that the two theories are placed in the same space-time volume. This conjecture is verified independently for $U(1{)}_{em}$ and for $QCD$. In this framework and from this perspective we show that the group $SO(10)$ is the only viable candidate among the supersymmetric GUT groups $SU(5)$, $SO(10)$ and $E_6$.

   hep-ph0 citations
7. 07*

   Estimation of nucleon D-term in QCD

   I.V. Anikin🇷🇺

   Using the light-cone sum rules at leading order, we present an approach to perform the preliminary upper estimation for the nucleon gravitational form factor $D(t)$ ($D$-term contribution). Comparison with the experimental data and with the results of different models is discussed.

   hep-phParticles(2019)·6 citations
8. 08*

   A look at multiplicity distributions via modified combinants

   M.Rybczynski🇵🇱 · Z.Wlodarczyk🇵🇱 · G.Wilk🇵🇱

   The experimentally measured multiplicity distributions exhibit, after closer inspection, peculiarly enhanced void probability and oscillatory behavior of the modified combinants. We show that both these features can be used as additional sources of information, not yet fully explored, on the mechanism of multiparticle production. We provide their theoretical understanding within the class of compound distributions.

   hep-phnucl-thUkr.J.Phys.(2019)·4 citations
9. 09*

   On the direct determination of ${\sin }^2{\theta }_{eff}^{\ell }$ at hadron colliders

   Mauro Chiesa🇩🇪 · Fulvio Piccinini🇮🇹 · Alessandro Vicini🇮🇹

   We discuss the renormalization of the electroweak Standard Model at 1-loop using the leptonic effective weak mixing angle as one of the input parameters. We evaluate the impact of this choice in the prediction of the forward-backward asymmetry for the neutral current Drell-Yan process. The proposed input scheme is suitable for a direct determination of the effective leptonic weak mixing angle from the experimental data.

   hep-phhep-exPRD(2019)·46 citations
10. 10*

    Exclusive Production Ratio of Neutral over Charged Kaon Pair in $e^{+}{e}^{-}$ Annihilation Continuum via `Straton Model'

    Yi Jin🇨🇳 · Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Zhao-Xia Meng🇨🇳 · Zong-Guo Si🇨🇳 · Tao Yao🇨🇳

    A completely relativistic quark model in the Bethe-Salpter framework is employed to calculate the exclusive production ratio of the neutral over charged Kaon pair in $e^{+}{e}^{-}$ annihilation continuum region for center of mass energies smaller than the $J/\Psi$ mass. The valence quark charge plays the key rôle. The cancellation of the diagrams for the same charge case (in $K_S+K_L$) and the non-cancellation of the diagrams for the different charge case (in $K^{-}+K^{+}$) lead to the ratio as $(m_s-m_d{)}^2/M_{Kaon}^2\sim 1/10$.

    hep-phPRC(2020)·10 citations
11. 11*

    NLO Corrections to Heavy Flavour Distributions in Polarized Deep-Inelastic Scattering

    Felix Hekhorn🇩🇪 · Marco Stratmann🇩🇪

    We present a first calculation of the heavy flavor contribution to the longitudinally polarized DIS structure function $g_1$, differential in the transverse momentum or the rapidity of the observed heavy antiquark $\overline{Q}$. All results are obtained at next-to-leading order accuracy with a newly developed parton-level Monte Carlo generator that also allows one to study observables associated with the heavy quark pair such as its invariant mass distribution or its correlation in azimuthal angle. First phenomenological studies are presented in a kinematic regime relevant for a future Electron-Ion Collider with a particular emphasis on the sensitivity to the helicity gluon distribution. Finally, we also provide first NLO results for the full neutral-current sector of polarized DIS, i.e., including contributions from Z-boson exchange.

    hep-phPoS(2019)·2 citations
12. 12*

    Baryon number fluctuations in the QCD phase diagram from Dyson-Schwinger equations

    Philipp Isserstedt🇩🇪 · Michael Buballa🇩🇪 · Christian S. Fischer🇩🇪 · Pascal J. Gunkel🇩🇪

    We present results for fluctuations of the baryon number for QCD at nonzero temperature and chemical potential. These are extracted from solutions to a coupled set of truncated Dyson-Schwinger equations for the quark and gluon propagators of Landau-gauge QCD with $N_f=2+1$ quark flavors, that has been studied previously. We discuss the changes of fluctuations and ratios thereof up to fourth order for several temperatures and baryon chemical potential up to and beyond the critical endpoint. In the context of preliminary STAR data for the skewness and kurtosis ratios, the results are compatible with the scenario of a critical endpoint at large chemical potential and slightly offset from the freeze-out line. We also discuss the caveats involved in this comparison.

    hep-phhep-exhep-latPRD(2019)·126 citations
13. 13*

    Gravitational wave and Collider searches for the EWSB patterns

    Ligong Bian🇨🇳 · Huai-Ke Guo🇺🇸 · Yongcheng Wu🇨🇦 · Ruiyu Zhou🇨🇳

    We study the Electroweak symmetry breaking mechanism with extra Electroweak symmetry breaking contributions (eEWSB) that are bounded by the Fermi constant and limits from the related collider searches. The eEWSB is helpful to build a different zero temperature vacuum structure from the Standard Model (SM), and therefore leads to different Electroweak phase transition patterns at the early Universe. We investigate the collider search prospects and gravitational waves (GW) predictions from the strongly firstly order phase transition (SFOEWPT) in this scenario. The Higgs pair searches at lepton colliders are found to be complementary with the GW searches of the SFOEWPT parameter spaces.

    hep-phPRD(2020)·51 citations
14. 14*

    A vector leptoquark for the B-physics anomalies from a composite GUT

    Leandro Da Rold🇦🇷 · Federico Lamagna🇦🇷

    A vector leptoquark at the TeV scale, mostly coupled to the fermions of the third generation, is the preferred option to explain the hints of lepton flavor universality violation in the decays of B-mesons. It seems interesting to assume that this leptoquark belongs to the same beyond the Standard Model sector that solves the hierarchy problem, since the third generation of fermions play the leading role in the instability of the Higgs potential. We present a composite Grand Unified Theory with resonances at the TeV that contains the required vector leptoquark and develops the Higgs as a pseudo Nambu-Goldstone boson. We show that anarchic partial compositeness of the Standard Model fermions can accommodate the couplings of Left-handed currents required by the B-anomalies, predicting very small couplings to the Right-handed currents without any additional hypothesis. By making use of an effective theory description of the strong dynamics, in terms of weakly coupled resonances, we are able to compute the corrections to B-physics, as well as the one-loop potential for the pseudo Nambu-Goldstone bosons. The theory has a rich phenomenology and a candidate for dark matter.

    hep-phhep-thJHEP(2019)·34 citations
15. 15*

    On amplitudes, resonances and the ultraviolet completion of gravity

    Rodrigo Alonso🇯🇵 · Alfredo Urbano🇮🇹

    This letter constructs, making use of the on-shell spinor-helicity formalism, a possible ultraviolet completion of gravity following a "bottom-up" approach. The assumptions of locality, unitarity and causality i) require an infinite tower of resonances with increasing spin and quantized mass, ii) introduce a duality relation among crossed scattering channels, and iii) dress all gravitational amplitudes in the Standard Model with a form factor that closely resembles either the Veneziano or the Virasoro-Shapiro amplitude in string theory. As a consequence of unitarity, the theory predicts leading order deviations from General Relativity in the coupling of gravity to fermions that could be explained if space-time has torsion in addition to curvature.

    hep-phgr-qchep-thPRD(2019)·13 citations
16. 16*

    Using Forward-Backward Drell-Yan Asymmetry in PDF Determinations

    Juri Fiaschi🇩🇪 · Elena Accomando🇬🇧 · Francesco Hautmann🇬🇧 · Stefano Moretti🇬🇧

    We study the impact of the inclusion of Neutral Current (NC) DY data from LHC mapped in the Forward-Backward Asymmetry ($A_{\mathrm{FB}}$) observable on PDF uncertainties, using the open source platform \texttt{xFitter}. We find that $A_{\mathrm{FB}}$ enables new PDF sensitivity at current and future luminosity stages of LHC.

    hep-phPoS(2019)·3 citations
17. 17*

    Pseudoscalar transition form factors and the hadronic light-by-light contribution to the anomalous magnetic moment of the muon from holographic QCD

    Josef Leutgeb🇦🇹 · Jonas Mager🇦🇹 · Anton Rebhan🇦🇹

    We revisit the predictions for the pseudoscalar-photon transition form factors in bottom-up and top-down holographic QCD models which only use the pion decay constant and the $\rho$ meson mass as input. We find remarkable agreement with the available experimental data for the single-virtual ${\pi }^0$ form factor that have recently been extended to lower momenta by BESIII, down to 0.3 GeV${}^2$. The bottom-up models moreover turn out to be roughly consistent with recent experimental results obtained by BaBar for the double-virtual ${\eta }^{\prime }$ form factor at large momenta as well as with a recent lattice extrapolation for the double-virtual ${\pi }^0$ form factor. Calculating the pion pole contribution to the hadronic light-by-light scattering in the anomalous magnetic moment of the muon, we find that the bottom-up models in question span the range $a_\mu^{\pi^0}=6.1(4)\cdot 10^{-10}, which is somewhat lower than estimated previously by approximating these holographic predictions through simple interpolators, and in remarkably good agreement with recent results based on a dispersive approach or lattice simulations.

    hep-phhep-thPRD(2019)·25 citations
18. 18*

    High-energy effects in forward inclusive dijet and hadron-jet production

    Andrèe Dafne Bolognino🇮🇹 · Francesco Giovanni Celiberto🇮🇹 · Dmitry Yu. Ivanov🇷🇺 · Mohammed M.A. Mohammed🇮🇹 · Alessandro Papa🇮🇹

    Pursuing the goal to single out the validity region of the high-energy resummation, better known as BFKL approach, and to possibly disentangle BFKL effects from the ones coming from a DGLAP-inspired, fixed-order description, new predictions for the forward inclusive hadron-jet production, tailored on the CMS and CASTOR acceptances, are given.

    hep-phPoS(2019)·50 citations
19. 19*

    Warm Little Inflaton becomes Dark Energy

    João G. Rosa🇵🇹 · Luís B. Ventura🇵🇹

    We present a model where the inflaton field behaves like quintessence at late times, generating the present phase of accelerated expansion. This is achieved within the framework of warm inflation, in particular the Warm Little Inflaton scenario, where the underlying symmetries guarantee a successful inflationary period in a warm regime sustained by dissipative effects without significant backreaction on the scalar potential. This yields a smooth transition into a radiation-dominated epoch, at which point dissipative effects naturally shut down as the temperature drops below the mass of the fermions directly coupled to the inflaton. The post-inflationary dynamics is then analogous to a thawing quintessence scenario, with no kination phase at the end of inflation. Observational signatures of this scenario include the modified consistency relation between the tensor-to-scalar ratio and tensor spectral index typical of warm inflation models, the variation of the dark energy equation of state at low redshifts characteristic of thawing quintessence scenarios, and correlated dark energy isocurvature perturbations.

    hep-phastro-ph.COgr-qchep-thPLB(2019)·40 citations
20. 20*

    Nonperturbative Corrections to Soft Drop Jet Mass

    André H. Hoang🇦🇹 · Sonny Mantry🇺🇸 · Aditya Pathak🇦🇹 · Iain W. Stewart🇺🇸

    We provide a quantum field theory based description of the nonperturbative effects from hadronization for soft drop groomed jet mass distributions using the soft-collinear effective theory and the coherent branching formalism. There are two distinct regions of jet mass $m_J$ where grooming modifies hadronization effects. In a region with intermediate $m_J$ an operator expansion can be used, and the leading power corrections are given by three universal nonperturbative parameters that are independent of all kinematic variables and grooming parameters, and only depend on whether the parton initiating the jet is a quark or gluon. The leading power corrections in this region cannot be described by a standard normalized shape function. These power corrections depend on the kinematics of the subjet that stops soft drop through short distance coefficients, which encode a perturbatively calculable dependence on the jet transverse momentum, jet rapidity, and on the soft drop grooming parameters $z_{\mathrm{cut}}$ and $\beta$. Determining this dependence requires a resummation of large logarithms, which we carry out at LL order. For smaller $m_J$ there is a nonperturbative region described by a one-dimensional shape function that is unusual because it is not normalized to unity, and has a non-trivial dependence on $\beta$.

    hep-phnucl-thJHEP(2019)·74 citations
21. 21*

    Improved axion emissivity from a supernova via nucleon-nucleon bremsstrahlung

    Pierluca Carenza (Bari U. & INFN Bari)🇮🇹 · Tobias Fischer (Wroclaw U.)🇵🇱 · Maurizio Giannotti (Barry U.)🇺🇸 · Gang Guo (Darmstadt, GSI)🇩🇪 · Gabriel Martinez-Pinedo (Darmstadt, GSI & Darmstadt, Tech. U.)🇩🇪 · Alessandro Mirizzi (Bari U. & INFN Bari)🇮🇹

    The most efficient axion production mechanism in a supernova (SN) core is the nucleon-nucleon bremsstrahlung. This process has been often modeled at the level of the vacuum one-pion exchange (OPE) approximation. Starting from this naive recipe, we revise the calculation including systematically different effects, namely a non-vanishing mass for the exchanged pion, the contribution from the two-pions exchange, effective in-medium nucleon masses and multiple nucleon scatterings. Moreover, we allow for an arbitrary degree of nucleon degeneracy. A self consistent treatment of the axion emission rate including all these effects is currently missing. The aim of this work is to provide such an analysis. Furthermore, we demonstrate that the OPE potential with all the previous corrections gives rise to similar results as the on-shell T-matrix, and is therefore well justified for our and similar studies. We find that the axion emissivity is reduced by over an order of magnitude with respect to the basic OPE calculation, after all these effects are accounted for. The implications for the axion mass bound and the impact for the next generation experimental axion searches is also discussed.

    hep-phastro-ph.SRJCAP(2019)·322 citations
22. 22*

    The single-jet inclusive cross-section and its definition

    Matteo Cacciari🇫🇷 · Stefano Forte🇮🇹 · Davide Napoletano🇫🇷 · Gregory Soyez🇫🇷 · Giovanni Stagnitto🇫🇷

    We investigate some well-known problematic aspects of the single-jet inclusive cross-section, specifically its non-unitarity and the possibly related issue of apparent perturbative instability at low orders. We study and clarify their origin by introducing possible alternative weighted definitions of the observable which restore unitarity. We show that the perturbative instability of the standard definition is an accidental artefact of the smallness of the NLO $K$ factor which only manifests itself for values of the jet radius in the range $R\sim 0.3-0.6$, and that its non-unitarity is necessary in order to ensure cancellation of logs of the momentum cutoff used in the jet definition. We also show that alternative unitary definitions do not have better perturbative properties compared to the conventional non-unitary definition, while suffering from lack of cancellation of large logs.

    hep-phhep-exPRD(2019)·12 citations
23. 23*

    Experimental searches for the chiral magnetic effect in heavy-ion collisions

    Jie Zhao🇺🇸 · Fuqiang Wang🇺🇸

    The chiral magnetic effect (CME) in quantum chromodynamics (QCD) refers to a charge separation (an electric current) of chirality imbalanced quarks generated along an external strong magnetic field. The chirality imbalance results from interactions of quarks, under the approximate chiral symmetry restoration, with metastable local domains of gluon fields of non-zero topological charges out of QCD vacuum fluctuations. Those local domains violate the $\mathcal{P}$ and $\mathcal{C}\mathcal{P}$ invariance, potentially offering a solution to the strong $\mathcal{C}\mathcal{P}$ problem in explaining the magnitude of the matter-antimatter asymmetry in today's universe. Relativistic heavy-ion collisions, with the likely creation of the high energy density quark-gluon plasma and restoration of the approximate chiral symmetry, and the possibly long-lived strong magnetic field, provide a unique opportunity to detect the CME. Early measurements of the CME-induced charge separation in heavy-ion collisions are dominated by physics backgrounds. Major efforts have been devoted to eliminate or reduce those backgrounds. We review those efforts, with a somewhat historical perspective, and focus on the recent innovative experimental undertakings in the search for the CME in heavy-ion collisions.

    ↳ nucl-exhep-exhep-phnucl-thPPNP(2019)·123 citations
24. 24*

    Numerical modeling of cosmic-ray transport in the heliosphere and interpretation of the proton-to-helium ratio in Solar Cycle 24

    Nicola Tomassetti🇮🇹 · Fernando Barão🇵🇹 · Bruna Bertucci🇮🇹 · Emanuele Fiandrini🇮🇹 · Miguel Orcinha🇵🇹

    Thanks to space-borne experiments of cosmic-ray (CR) detection, such as the AMS and PAMELA missions in low-Earth orbit, or the Voyager-1 spacecraft in the interstellar space, a large collection of multi-channel and time-resolved CR data has become available. Recently, the AMS experiment has released new precision data, on the proton and helium fluxes in CRs, measured on monthly basis during its first six years of mission. The AMS data reveal a remarkable long-term behavior in the temporal evolution of the proton-to-helium ratio at rigidity $R=p/Z<$ 3 GV. As we have argued in a recent work, such a behavior may reflect the transport properties of low-rigidity CRs in the inteplanetary space. In particular, it can be caused by mass/charge dependence of the CR diffusion coefficient. In this paper, we present our developments in the numerical modeling of CR transport in the Milky Way and in the heliosphere. Within our model, and with the help of approximated analytical solutions, we describe in details the relations between the properties of CR diffusion and the time-dependent evolution of the proton-to-helium ratio.

    ↳ astro-ph.HEastro-ph.SRhep-phphysics.space-phAdv.Space Res.(2019)·25 citations
25. 25*

    Theoretical study of ${}^{173}$YbOH to search for the nuclear magnetic quadrupole moment

    Daniel E. Maison🇷🇺 · Leonid V. Skripnikov🇷🇺 · Victor V. Flambaum🇦🇺

    CP-violating interaction of the nuclear magnetic quadrupole moment (MQM) with electrons in the ytterbium mono-hydroxide molecule, ${}^{173}$YbOH, is considered. Both the magnetic quadrupole moment (MQM) of the ${}^{173}$Yb nucleus and the molecular interaction constant WM are estimated. Electron correlation effects are taken into account within the relativistic Fock-space coupled cluster method. Results are interpreted in terms of the strength constants of CP-violating nuclear forces, neutron EDM, QCD vacuum angle $\theta$, quark EDM and chromo-EDM.

    ↳ physics.atom-phhep-phnucl-thPRA(2019)·47 citations
26. 26*

    Probing Primordial-Black-Hole Dark Matter with Scalar Induced Gravitational Waves

    Chen Yuan🇨🇳 · Zu-Cheng Chen🇨🇳 · Qing-Guo Huang🇨🇳

    The possibility that primordial black holes (PBHs) represent all of the dark matter (DM) in the Universe and explain the coalescences of binary black holes detected by LIGO/Virgo has attracted a lot of attention. PBHs are generated by the enhancement of scalar perturbations which inevitably produce the induced gravitational waves (GWs). We calculate the induced GWs up to the third-order correction which not only enhances the amplitude of induced GWs, but also extends the cutoff frequency from $2k_{\ast }$ to $3k_{\ast }$. Such effects of the third-order correction lead to an around $10\%$ increase of the signal-to-noise ratio (SNR) for both LISA and pulsar timing array (PTA) observations, and significantly widen the mass range of PBHs in the stellar mass window accompanying detectable induced GWs for PTA observations including IPTA, FAST and SKA. On the other hand, the null detections of the induced GWs by LISA and PTA experiments will exclude the possibility that all of the DM is comprised of PBHs and the GW events detected by LIGO/Virgo are generated by PBHs.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2019)·115 citations
27. 27*

    Weyl $R^2$ inflation with an emergent Planck scale

    D. M. Ghilencea🇷🇴

    We study inflation in Weyl gravity. The original Weyl quadratic gravity, based on Weyl conformal geometry, is a theory invariant under Weyl symmetry of (gauged) local scale transformations. In this theory Planck scale ($M$) emerges as the scale where this symmetry is broken spontaneously by a geometric Stueckelberg mechanism, to Einstein-Proca action for the Weyl "photon" (of mass near $M$). With this action as a "low energy" broken phase of Weyl gravity, century-old criticisms of the latter (due to non-metricity) are avoided. In this context, inflation with field values above $M$ is natural, since this is just a phase transition scale from Weyl gravity (geometry) to Einstein gravity (Riemannian geometry), where the massive Weyl photon decouples. We show that inflation in Weyl gravity coupled to a scalar field has results close to those in Starobinsky model (recovered for vanishing non-minimal coupling), with a mildly smaller tensor-to-scalar ratio ($r$). Weyl gravity predicts a specific, narrow range $0.00257\le r\le 0.00303$, for a spectral index $n_s$ within experimental bounds at $68\%$CL and e-folds number $N=60$. This range of values will soon be reached by CMB experiments and provides a test of Weyl gravity. Unlike in the Starobinsky model, the prediction for $(r,n_s)$ is not affected by unknown higher dimensional curvature operators (suppressed by some large mass scale) since these are forbidden by the Weyl gauge symmetry.

    ↳ gr-qcastro-ph.COhep-phhep-thJHEP(2019)·74 citations
28. 28*

    Dark matter capture by the Sun: revisiting velocity distribution uncertainties

    A.Nuñez-Castiñeyra🇫🇷 · E.Nezri🇫🇷 · V.Bertin🇫🇷

    Among the different strategies aiming to detect WIMP dark matter (DM), a neutrino signal coming from the Sun would be a smoking gun. This possibility relies on the DM capture by the Sun driven by the local DM distribution assumptions: the local mass density and the velocity distribution. In this context, we revisit those astrophysical hypotheses (also relevant for direct detection). We focus especially on the DM velocity distribution considering different possibilities beyond the popular Maxwellian distribution. Namely, some alternatives can be considered through analytical approaches and by looking into cosmological simulations of spiral galaxies. Most of the fitting formulas used to constrain the local velocity distribution function fail to describe the peak and the high velocity tail of the velocity distribution observed in simulations, the latter being improved when adding the local escape velocity of DM into the benchmark fitting models. In addition we test the predictions by the Eddington inversion method and also illustrate the importance of the galactic dynamical history. We estimate the resulting uncertainties on the DM capture rate by the Sun and conclude that different velocity distributions will affect the capture rate of DM by the Sun up to a $15-20\%$. On top of that, the calculation of the intrinsic variance of the capture rate leads to poorly controlled uncertainties especially for high WIMP masses ($>$30 GeV) raising concerns about the capture scenario.

    ↳ astro-ph.GAastro-ph.COhep-phJCAP(2019)·27 citations
29. 29*

    Anomalous ANITA air shower events and tau decays

    Shoshana Chipman🇺🇸 · Rebecca Diesing🇺🇸 · Mary Hall Reno🇺🇸 · Ina Sarcevic🇺🇸

    Two unusual neutrino events in the Antarctic Impulse Transient Antenna (ANITA) appear to have been generated by air showers from a particle emerging from the Earth at angles 25-35 degrees above the horizon. We evaluate the effective aperture for ANITA with a simplified detection model to illustrate the features of the angular dependence of expected events for incident standard model tau neutrinos and for sterile neutrinos that mix with tau neutrinos. We apply our sterile neutrino aperture results to a dark matter scenario with long-lived supermassive dark matter that decay to sterile neutrino-like particles. We find that for up-going air showers from tau decays, from isotropic fluxes of standard model, sterile neutrinos or other particles that couple to the tau through suppressed weak interaction cross sections cannot be responsible for the unusual events.

    ↳ astro-ph.HEhep-phPRD(2019)·21 citations
30. 30*

    Axion dark matter from Higgs inflation with an intermediate $H_{\ast }$

    Tommi Tenkanen🇺🇸 · Luca Visinelli🇳🇱

    In order to accommodate the QCD axion as the dark matter (DM) in a model in which the Peccei-Quinn (PQ) symmetry is broken before the end of inflation, a relatively low scale of inflation has to be invoked in order to avoid bounds from DM isocurvature fluctuations, $H_{\ast }\lesssim \mathcal{O}(10^9)$GeV. We construct a simple model in which the Standard Model Higgs field is non-minimally coupled to Palatini gravity and acts as the inflaton, leading to a scale of inflation $H_{\ast }\sim 10^8$GeV. When the energy scale at which the PQ symmetry breaks is much larger than the scale of inflation, we find that in this scenario the required axion mass for which the axion constitutes all DM is $m_0\lesssim 0.05\mu \mathrm{eV}$ for a quartic Higgs self-coupling ${\lambda }_{\varphi }=0.1$, which correspond to the PQ breaking scale $v_{\sigma }\gtrsim 10^{14}$GeV and tensor-to-scalar ratio $r\sim 10^{-12}$. Future experiments sensitive to the relevant QCD axion mass scale can therefore shed light on the physics of the Universe before the end of inflation.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2019)·54 citations
31. 31*

    Heavy Spinning Particles from Signs of Primordial Non-Gaussianities: Beyond the Positivity Bounds

    Suro Kim🇯🇵 · Toshifumi Noumi🇯🇵 · Keito Takeuchi🇯🇵 · Siyi Zhou🇨🇳

    Within the so-called cosmological collider program, imprints of new particles on primordial non-Gaussianities have been studied intensively. In particular, their non-analytic features in the soft limit provide a smoking gun for new particles at the inflation scale. While this approach is very powerful to probe particles of the mass near the Hubble scale, the signal is exponentially suppressed for heavy particles. In this paper, to enlarge the scope of the cosmological collider, we explore a new approach to probing spins of heavy particles from signs of Wilson coefficients of the inflaton effective action and the corresponding primordial non-Gaussianities. As a first step, we focus on the regime where the de Sitter conformal symmetry is weakly broken. It is well known that the leading order effective operator $({\partial }_{\mu }\varphi {\partial }^{\mu }\varphi {)}^2$ is universally positive as a consequence of unitarity. In contrast, we find that the sign of the six derivative operator $({\nabla }_{\mu }{\partial }_{\nu }\varphi {)}^2({\partial }_{\rho }\varphi {)}^2$ is positive for intermediate heavy scalars, whereas it is negative for intermediate heavy spinning states. Therefore, under the assumption of tree-level UV completion, the sign can be used to probe spins of heavy particles generating the effective interaction. We also study phenomenology of primordial non-Gaussianities thereof.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2019)·53 citations
32. 32*

    Extreme Dark Matter Tests with Extreme Mass Ratio Inspirals

    Otto A. Hannuksela🇳🇱 · Kenny C. Y. Ng🇮🇱 · Tjonnie G. F. Li🇨🇳

    Future space-based laser interferometry experiments such as LISA are expected to detect $\mathcal{O}$(100--1000) stellar-mass compact objects (e.g., black holes, neutron stars) falling into massive black holes in the centers of galaxies, the so-called extreme-mass-ratio inspirals (EMRIs). If dark matter forms a "spike" due to the growth of the massive black hole, it will induce a gravitational drag on the inspiraling object, changing its orbit and gravitational-wave signal. We show that detection of even a single dark matter spike from the EMRIs will severely constrain several popular dark matter candidates, such as ultralight bosons, keV fermions, MeV--TeV self-annihilating dark matter, and sub-solar mass primordial black holes, as these candidates would flatten the spikes through various mechanisms. Future space gravitational wave experiments could thus have a significant impact on the particle identification of dark matter.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ex+1PRD(2020)·101 citations
33. 33*

    Ultra-light Dark Matter is Incompatible with the Milky Way's Dwarf Satellites

    Mohammadtaher Safarzadeh🇺🇸 · David N. Spergel🇺🇸

    The density profiles of dwarf galaxies are a highly varied set. If the dark matter is an ultra-light particle such as axions, then simulations predict a distinctive and unique profile. If the axion mass is large enough to fit the ultra-faint dwarf (UFD) satellites($m⪆10^{-21}$ eV), then the models do not fit the density profile of Fornax and Sculptor and are ruled out by more than $3-\sigma$ confidence. If the axion mass is in the mass range that can fit mass profiles of Fornax and Sculptor dwarf spheroidals, then its extended profile implies enormous masses ($\approx 10^{11}-10^{12}{M}_{\odot }$) for the UFDs. These large masses for the UFDS are ruled out by more than $3-\sigma$ confidence by dynamical friction arguments. The tension would increase further considering star formation histories and stellar masses of the UFDs. Unless future ultra-light dark matter (ULDM) simulations with baryonic feedback show a significant change in the density structure of the halos, the current data is incompatible with the ULDM scenario. Relaxing the slope constraint from classical dwarf galaxies would lead to excluding ULDM with mass less than $6\times 10^{-22}$ eV.

    ↳ astro-ph.COastro-ph.GAhep-ph124 citations
34. 34*

    Axion clockworks from heterotic M-theory: the QCD-axion and its ultra-light companion

    Sang Hui Im🇰🇷 · Hans Peter Nilles🇩🇪 · Marek Olechowski🇵🇱

    A previously discussed clockwork mechanism within heterotic M-theory is applied to its axion landscape. We identify a unique candidate for a QCD-axion with a decay constant in the preferred "axion window" around $10^{11}$GeV. It is accompanied by at least one ultra-light axion that couples predominantly to hidden sector gauge groups.

    ↳ hep-thhep-phJHEP(2019)·10 citations
35. 35*

    Statistical Methods Applied to the Search of Sterile Neutrinos

    Matteo Agostini🇩🇪 · Birgit Neumair🇩🇪

    The frequentist statistical methods applied to search for short-baseline neutrino oscillations induced by a sterile neutrino with mass at the eV scale are reviewed and compared. The comparison is performed under limit setting and signal discovery scenarios, considering both when an oscillation would enhance the neutrino interaction rate in the detector and when it would reduce it. The sensitivity of the experiments and the confidence regions extracted for specific data sets change considerably according to which test statistic is used and the assumptions on its probability distribution. A standardized analysis approach based on the most general kind of hypothesis test is proposed.

    ↳ hep-exhep-phnucl-exphysics.data-anEPJC(2020)·30 citations
36. 36*

    Quantization of nonlocal fractional field theories via the extension problem

    Antonia Micol Frassino🇪🇸 · Orlando Panella🇮🇹

    We use the extension problem proposed by Caffarelli and Silvestre to study the quantization of a scalar nonlocal quantum field theory built out of the fractional Laplacian. We show that the quantum behavior of such a nonlocal field theory in $d$-dimensions can be described in terms of a local action in $d+1$ dimensions which can be quantized using the canonical operator formalism though giving up local commutativity. In particular, we discuss how to obtain the two-point correlation functions and the vacuum energy density of the nonlocal fractional theory as a brane limit of the bulk correlators. We show explicitly how the quantized extension problem reproduces exactly the same particle content of other approaches based on the spectral representation of the fractional propagator. We also briefly discuss the inverse fractional Laplacian and possible applications of this approach in general relativity and cosmology.

    ↳ hep-thhep-phmath-phmath.MPPRD(2019)·14 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.