Fri·Jul 12, 2019Friday·July 12, 2019

1. 01*

   Gravitational and Chiral Anomalies in the Running Vacuum Universe and Matter-Antimatter Asymmetry

   Spyros Basilakos🇬🇷 · Nick E. Mavromatos🇬🇧 · Joan Sola🇪🇸

   We present a model for the Universe in which quantum anomalies are argued to play an important dual role: they are responsible for generating matter-antimatter asymmetry, but also provide time-dependent contributions to the vacuum energy density of "running-vacuum" type, which drive the Universe evolution. During the inflationary phase of a string-inspired Universe, and its subsequent exit, the existence of primordial gravitational waves induce gravitational anomalies, which couple to the Kalb-Ramond (KR)axion field of the massless gravitational string multiplet. Such anomalous CP violating interactions have two important effects: first, they lead to contributions to the vacuum energy density of the form appearing in the "running vacuum model" (RVM) framework, proportional to both the square and the fourth power of the effective Hubble parameter $H$, the $H^4$ terms being associated with anomaly-induced inflation within the RVM framework. Second, there is an undiluted KR axion at the end of inflation, which plays an important role in generating matter-antimatter asymmetry through baryogenesis via leptogenesis in models with heavy right handed neutrinos. As the Universe exits inflation and enters a radiation dominated era, the generation of chiral fermionic matter is responsible for the cancellation of gravitational anomalies, thus restoring diffeomorphism invariance for the matter/radiation (quantum) theory, as required for consistency. Chiral U(1) anomalies may remain uncompensated, though, during matter/radiation dominance, providing RVM-like $H^2$ and $H^4$ contributions to the Universe energy density. Finally, in the current era, gravitational anomalies resurface, leading to much weaker RVM-like $H_0^2$ contributions to the vacuum energy density.Our model favours axionic Dark Matter,the source of which can be the KR axion.

   hep-phgr-qchep-thPRD(2020)·99 citations
2. 02*

   Automated simulations beyond the Standard Model: supersymmetry

   Stefano Frixione🇮🇹 · Benjamin Fuks🇫🇷 · Valentin Hirschi🇨🇭 · Kentarou Mawatari🇯🇵 · Hua-Sheng Shao🇫🇷 · Marthijn P. A. Sunder🇩🇪 · Marco Zaro🇳🇱

   The MadGraph5 aMC@NLO framework aims to automate all types of leading- and next-to-leading-order-accurate simulations for any user-defined model that stems from a renormalisable Lagrangian. In this paper, we present all of the key ingredients of such models in the context of supersymmetric theories. In order to do so, we extend the FeynRules package by giving it the possibility of dealing with different renormalisation options that are relevant to supersymmetric models. We also show how to deal with the problem posed by the presence of narrow resonances, thus generalising the so-called on-shell subtraction approaches. We extensively compare our total rate results with those of both Prospino2 and Resummino, and present illustrative applications relevant to the 13 TeV LHC, both at the total-rate and differential levels. The computer programs that we have used to obtain the predictions presented here are all publicly available.

   hep-phhep-exJHEP(2019)·64 citations
3. 03*

   Two- and three-loop anomalous dimensions of Weinberg's dimension-six CP-odd gluonic operator

   Jordy de Vries🇺🇸 · Giulio Falcioni🇬🇧 · Franz Herzog🇳🇱 · Ben Ruijl🇨🇭

   We apply a fully automated extension of the $R^{\ast }$-operation capable of calculating higher-loop anomalous dimensions of n-point Green's functions of arbitrary, possibly non-renormalisable, local Quantum Field Theories. We focus on the case of the CP-violating Weinberg operator of the Standard Model Effective Field Theory whose anomalous dimension is so far known only at one loop. We calculate the two-loop anomalous dimension in full QCD and the three-loop anomalous dimensions in the limit of pure Yang-Mills theory. We find sizeable two-loop and large three-loop corrections, due to the appearance of a new quartic group invariant. We discuss phenomenological implications for electric dipole moments and future applications of the method.

   hep-phPRD(2020)·53 citations
4. 04*

   Constraints on neutrino electric millicharge from experiments of elastic neutrino-electron interaction and future experimental proposals involving coherent elastic neutrino-nucleus scattering

   A. Parada🇨🇴

   In several extensions of the Standard Model of Particle Physics (SMPP), the neutrinos acquire electromagnetic properties such as the electric millicharge. Theoretical and experimental bounds have been reported in the literature for this parameter. In this work, we first carried out a statistical analysis by using data from reactor neutrino experiments, which include elastic neutrino-electron scattering (ENES) processes, in order to obtain both individual and combined limits on the neutrino electric millicharge (NEM). Then we performed a similar calculation to show a estimate of the sensitivity of future experiments of reactor neutrinos to the NEM, by involving coherent elastic neutrino-nucleus scattering (CENNS). In the first case, the constraints achieved from the combination of several experiments are $-1.1\times 10^{-12}e<q_{\nu }<9.3\times 10^{-13}e$ ($90\%$ C.L.), and in the second scenario we obtained the bounds $-1.8\times 10^{-14}e<q_{\nu }<1.8\times 10^{-14}e$ ($90\%$ C.L.). As we will show here, these combined analyses of different experimental data can lead to stronger constraints than those based on individual analysis. Where CENNS interactions would stand out as an important alternative to improve the current limits on NEM.

   hep-phhep-exAdv.High Energy Phys.(2020)·26 citations
5. 05*

   Regge behaviors in orbitally excited spectroscopy of charmed and bottom baryons

   Duojie Jia🇨🇳 · Wen-Nian Liu🇨🇳 · Atsushi Hosaka🇯🇵

   Stimulated by recent progress made by the LHCb Collaboration in discoveries of new bottom baryons, e.g., the ${\Xi }_b(6227{)}^{-}$ and the ${\Sigma }_b(6097{)}^{\pm }$, we re-examine the orbitally excited spectrum of the charmed and bottom baryons using Regge approach in the heavy quark-diquark picture. The results indicate that the spin-averaged mass spectrum of the orbitally-excited charmed and bottom baryons can be described by a linear Regge relation, which is derived from the rotating QCD string model. By giving further mass-splitting analysis of spin-dependent interactions, we explain the baryons ${\Xi }_b(6227{)}^{-}$ and the ${\Sigma }_b(6097{)}^{\pm }$,and the ${\Sigma }_c(2800)$ and ${\Xi }_c^{\prime }(2930)$ to be the $1P$%-wave baryons, all with the spin-parity $J^P=3/2^{-}$ preferably. Mass prediction of the bottom baryon ${\Xi }_b$ in its P- and D-waves are presented, providing clues for the coming experiments like the LHCb to find them.

   hep-phhep-exPRD(2020)·50 citations
6. 06*

   Is there a supernova bound on axions?

   Nitsan Bar🇮🇱 · Kfir Blum🇮🇱 · Guido D'Amico🇺🇸

   We present a critical assessment of the SN1987A supernova cooling bound on axions and other light particles. Core-collapse simulations used in the literature to substantiate the bound omitted from the calculation the envelope exterior to the proto-neutron star (PNS). As a result, the only source of neutrinos in these simulations was, by construction, a cooling PNS. We show that if the canonical delayed neutrino mechanism failed to explode SN1987A, and if the pre-collapse star was rotating, then an accretion disk would form that could explain the late-time ($t\gtrsim 5$ sec) neutrino events. Such accretion disk would be a natural feature if SN1987A was a collapse-induced thermonuclear explosion. Axions do not cool the disk and do not affect its neutrino output, provided the disk is optically-thin to neutrinos, as it naturally is. These considerations cast doubt on the supernova cooling bound.

   hep-phastro-ph.HEPRD(2020)·220 citations
7. 07*

   Charmed baryon$-$nucleon interaction

   H. Garcilazo🇲🇽 · A. Valcarce🇪🇸 · T.F. Carames🇪🇸

   We present a comparative study of the charmed baryon$-$nucleon interaction based on different theoretical approaches. For this purpose, we make use of i) a constituent quark model tuned in the light-flavor baryon$-$baryon interaction and the hadron spectra, ii) existing results in the literature based both on hadronic and quark-level descriptions, iii) (2+1)-flavor lattice QCD results of the HAL QCD Collaboration at unphysical pion masses and their effective field theory extrapolation to the physical pion mass. There is a general qualitative agreement among the different available approaches to the charmed baryon$-$nucleon interaction. Different from hadronic models based on one-boson exchange potentials, quark$-$model based results point to soft interactions without two-body bound states. They also support a negligible channel coupling, due either to tensor forces or to transitions between different physical channels, ${\Lambda }_{c}N-{\Sigma }_{c}N$. Short-range gluon and quark-exchange dynamics generate a slightly larger repulsion in the ${}^1{S}_0$ than in the ${}^3{S}_1$ ${\Lambda }_{c}N$ partial wave. A similar asymmetry between the attraction in the two $S$ waves of the ${\Lambda }_{c}N$ interaction also appears in hadronic approaches. A comparative detailed study of Pauli suppressed partial waves, as the ${}^1{S}_0(I=1/2)$ and ${}^3{S}_1(I=3/2)$ ${\Sigma }_{c}N$ channels, would help to disentangle the short-range dynamics of two-baryon systems containing heavy flavors. The possible existence of charmed hypernuclei is discussed.

   hep-phnucl-thEPJC(2019)·14 citations
8. 08*

   Towards a new generation of parton densities with deep learning models

   Stefano Carrazza🇮🇹 · Juan Cruz-Martinez🇮🇹

   We present a new regression model for the determination of parton distribution functions (PDF) using techniques inspired from deep learning projects. In the context of the NNPDF methodology, we implement a new efficient computing framework based on graph generated models for PDF parametrization and gradient descent optimization. The best model configuration is derived from a robust cross-validation mechanism through a hyperparametrization tune procedure. We show that results provided by this new framework outperforms the current state-of-the-art PDF fitting methodology in terms of best model selection and computational resources usage.

   hep-phhep-exEPJC(2019)·53 citations
9. 09*

   Partial decay widths of $P_c(4312)$ as a $\bar{D}{\Sigma }_c$ molecular state

   Yong-Jiang Xu🇨🇳 · Chun-Yu Cui🇨🇳 · Yong-Lu Liu🇨🇳 · Ming-Qiu Huang🇨🇳

   In the present work, the partial decay widths of $P_c(4312)$ to ${\eta }_{c}p$ and $J/\psi p$ are investigated with the QCD sum rule method under the assumption that $P_c(4312)$ is a $\bar{D}{\Sigma }_c$ molecular state with $J^P={\frac{1}{2}}^{-}$. In the analysis, the pole residue of $P_c(4312)$, one of the input parameters for the calculations of the strong decay constants, is calculated first. With the numerical values of the strong decay constants, the partial decay widths to ${\eta }_{c}p$ and $J/\psi p$ are estimated to be $\Gamma (P_c(4312)\to {\eta }_{c}p)=5.54_{-0.5}^{+0.75}\text{mbox}MeV$ and $\Gamma (P_c(4312)\to J/\psi p)=1.67_{-0.56}^{+0.92}\text{mbox}MeV$, respectively, which are compatible with the measured total width of $P_c(4312)$. The results suggest that it is reasonable to assign $P_c(4312)$ to be a $\bar{D}{\Sigma }_c$ molecular state with $J^P={\frac{1}{2}}^{-}$.

   hep-phPRD(2020)·44 citations
10. 10*

    Flavour anomalies and (fundamental) partial compositeness

    Peter Stangl🇫🇷

    Several measurements of B-meson decay observables show deviations from Standard Model (SM) predictions, some of them hinting at violation of lepton flavour universality (LFU). I discusses how the anomalies in rare B decays can be explained by partial compositeness. Partial compositeness is a key ingredient of models with a composite Higgs boson and generically leads to violation of LFU. After presenting a simple model with partial compositeness that is able to explain the anomalies in rare B decays, the flavour phenomenology of a minimal UV completion of a composite Higgs model with partial compositeness is discussed: the minimal fundamental partial compositeness (MFPC) model. A virtue of the MFPC model is its capability of serving both as a solution to the naturalness problem of the SM and as an explanation of the flavour anomalies in rare B-meson decays. In view of recent new measurements, the results on which this proceedings contribution is based are updated.

    hep-phPoS(2019)·1 citation
11. 11*

    Spectrum of the fully-heavy tetraquark state $QQ{\bar{Q}}^{\prime }{\bar{Q}}^{\prime }$

    Guang-Juan Wang🇨🇳 · Lu Meng🇨🇳 · Shi-Lin Zhu🇨🇳

    In this work, we systematically calculate the mass spectra of the $S$-wave fully heavy tetraquark states $bb\bar{b}\bar{b}$, $cc\bar{c}\bar{c}$, and $bb\bar{c}\bar{c}$ in two nonrelativistic quark models. A tetraquark state may be an admixture of a $6_c-{\bar{6}}_c$ state and a ${\bar{3}}_c-3_c$ one, where $6_c-{\bar{6}}_c$(${\bar{3}}_c-3_c$) denotes the color configuration with a $6_c$ (${\bar{3}}_c$) diquark and a ${\bar{6}}_c$ ($3_c$) antidiquark. For the tetraquark states $bb\bar{b}\bar{b}$ and $cc\bar{c}\bar{c}$ with $J^{PC}=0^{++}$, the $6_c-{\bar{6}}_c$ state is lower than the ${\bar{3}}_c-3_c$ one in both the two quark models, while the order of the $bb\bar{c}\bar{c}$ states depend on models. The $6_c-{\bar{6}}_c$ and ${\bar{3}}_c-3_c$ mixing effects are induced by the hyperfine interactions between the diquark and antidiquark, while the contributions from the one-gluon-exchange (OGE) Coulomb or the linear confinement potentials vanish for the $QQ{\bar{Q}}^{\prime }{\bar{Q}}^{\prime }$ system. With the couple-channel effects, we obtain the similar mass spectra. The numerical results show that the ground $QQ{\bar{Q}}^{\prime }{\bar{Q}}^{\prime }$ ($Q=b,c$ and $Q^{\prime }=b,c$) tetraquark states are located above the corresponding scattering states, which indicates that there may not exist a bound state in the scheme of the two quark models.

    hep-phPRD(2019)·142 citations
12. 12*

    Searching for CPT Violation with Neutral-Meson Oscillations

    Benjamin R. Edwards🇺🇸 · Alan Kostelecky🇺🇸

    A general technique is presented for treating CPT violation in neutral-meson oscillations. The effective field theory for a complex scalar with CPT-violating operators of arbitrary mass dimension is incorporated in the formalism for the propagation and mixing of neutral mesons. Observable effects are discussed, and first measurements of CPT-violating operators of dimension five are extracted from existing experimental results.

    hep-phPLB(2019)·29 citations
13. 13*

    The angular momentum decomposition in the scalar diquark model

    D. A. Amor-Quiroz🇫🇷 · M. Burkardt🇺🇸 · C. Lorcé🇫🇷

    One of the challenges of hadronic physics is to fully understand the structure of the proton. In particular, there is nowadays a great interest in the decomposition of its total angular momentum into orbital angular momentum and intrinsic spin, as well as identifying contributions from valence quarks, sea quarks and gluons. The most common decompositions of angular momentum are the Jaffe-Manohar (canonical) and Ji (kinetic) decompositions, which differ in the way contributions are attributed to quarks and gluons. Using perturbation theory, explicit one-loop calculations found that the difference between such decompositions vanishes. We justify within the diquark model in QED that the difference appears at two-loop level, supporting the interpretation of such a difference as originating from the torque exerted by the spectator system on the struck quark.

    hep-phnucl-thPoS(2019)·2 citations
14. 14*

    One pion exchange and the quantum numbers of the Pc(4440) and Pc(4457) pentaquarks

    Manuel Pavon Valderrama🇨🇳

    The LHCb collaboration has recently discovered three pentaquark-like states --- the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ --- close to the $\bar{D}{\Sigma }_c$ and the ${\bar{D}}^{\ast }{\Sigma }_c$ meson-baryon thresholds. The standard interpretation is that they are heavy antimeson-baryon molecules. Their quantum numbers have not been determined yet, which implies two possibilities for the $P_c(4440)$ and $P_c(4457)$: $J^P={\frac{1}{2}}^{-}$ and $J^P={\frac{3}{2}}^{-}$. The preferred interpretation within a contact-range effective field theory is that the $P_c(4440)$ is the $J^P={\frac{1}{2}}^{-}$ molecule, while the $P_c(4457)$ is the $J^P={\frac{3}{2}}^{-}$ one. Here we show that when the one pion exchange potential between the heavy-antimeson and heavy-baryon is taken into account, this conclusion changes, with the contrary identification being as likely as the original one. The identification is however cutoff dependent, which suggests that improvements of the present description (e.g. the inclusion of subleading order corrections, like two-pion exchanges) are necessary in order to disambiguate the spectroscopy of the molecular pentaquarks.

    hep-phhep-exnucl-thPRD(2019)·88 citations
15. 15*

    Electrical conductivity and Hall conductivity of hot and dense quark gluon plasma in a magnetic field: a quasi particle approach

    Arpan Das🇮🇳 · Hiranmaya Mishra🇮🇳 · Ranjita K. Mohapatra🇮🇳

    We estimate here the electrical and Hall conductivity using a quasiparticle approach for quark matter. We use a Boltzmann kinetic approach in presence of external magnetic field. We confront the results of model calculations with Lattice QCD simulations for vanishing magnetic field. In general electrical conductivity decreases with magnetic field. The Hall conductivity on the other hand can show a non monotonic behaviour with magnetic field due to an intricate interplay of behaviour of relaxation time and strength of the magnetic field. We argue for vanishing quark chemical potential Hall conductivity vanishes and quark gluon plasma with finite quark chemical potential can show Hall effect. Both electrical conductivity and Hall conductivity increases with increasing quark chemical potential.

    hep-phnucl-thPRD(2020)·54 citations
16. 16*

    Five-flavor pentaquarks and other light- and heavy-flavor symmetry partners of the LHCb hidden-charm pentaquark

    Fang-Zheng Peng🇨🇳 · Ming-Zhu Liu🇨🇳 · Ya-Wen Pan🇨🇳 · Mario Sánchez Sánchez🇫🇷 · Manuel Pavon Valderrama🇨🇳

    The discovery of three pentaquark peaks -- the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ -- by the LHCb collaboration has a series of interesting consequences for hadron spectroscopy. If these hidden-charm objects are indeed hadronic molecules, as suspected, they will be constrained by heavy-flavor and SU(3)-flavor symmetries. The combination of these two symmetries will imply the existence of a series of five-flavor pentaquarks with quark content $\bar{b}csdu$ and $b\bar{c}sdu$, that is, pentaquarks that contain each of the five quark flavors that hadronize. In addition, from SU(3)-flavor symmetry alone we expect the existence of light-flavor partners of the three $P_c$ pentaquarks with strangeness $S=-1$ and $S=-2$. The resulting structure for the molecular pentaquarks is analogous to the light-baryon octet -- we can label the pentaquarks as $P_{Q^{\prime }\bar{Q}}^N$, $P_{Q^{\prime }\bar{Q}}^{\Lambda }$, $P_{Q^{\prime }\bar{Q}}^{\Sigma }$, $P_{Q^{\prime }\bar{Q}}^{\Xi }$ depending on their heavy- and light-quark content (with $N$, $\Lambda$, $\Sigma$, $\Xi$ the member of the light-baryon octet to which the light-quark structure resembles and $Q^{\prime }$, $\bar{Q}$ the heavy quark-antiquark pair). In total we predict $45$ new pentaquarks from heavy- and light-flavor symmetries alone, which extend up to $109$ undiscovered states if we also consider heavy-quark spin symmetry. If an isoquartet ($I=3/2$) hidden-charm pentaquark is ever observed, this will in turn imply a second multiplet structure resembling the light-baryon decuplet: $P_{Q^{\prime }\bar{Q}}^{\Delta }$, $P_{Q^{\prime }\bar{Q}}^{{\Sigma }^{\ast }}$, $P_{Q^{\prime }\bar{Q}}^{{\Xi }^{\ast }}$, $P_{Q^{\prime }\bar{Q}}^{\Omega }$.

    hep-phhep-exhep-latnucl-thNPB(2022)·28 citations
17. 17*

    Radiative neutrino masses and successful $SU(5)$ unification

    Christiane Klein🇩🇪 · Manfred Lindner🇩🇪 · Stefan Vogl🇩🇪

    Minimal $SU(5)$ Grand Unified models predict massless neutrinos and struggle to achieve gauge coupling unification compatible with the observed lower limit on the proton lifetime. Both of these issues can be resolved by embedding minimal radiative neutrino mass models into $SU(5)$. We systematically analyze the possible ways to realize radiative neutrino mass generation in $SU(5)$ and provide a list of the minimal models. We find various models that have not been considered in the literature and demonstrate the compatibility of radiative neutrino masses with gauge coupling unification and proton decay for a new class of models with vector-like fermions.

    hep-phPRD(2019)·20 citations
18. 18*

    The Selfish Higgs

    G.F. Giudice🇨🇭 · A. Kehagias🇬🇷 · A. Riotto🇨🇭

    We propose a mechanism to solve the Higgs naturalness problem through a cosmological selection process. The discharging of excited field configurations through membrane nucleation leads to discrete jumps of the cosmological constant and the Higgs mass, which vary in a correlated way. The resulting multitude of universes are all empty, except for those in which the cosmological constant and the Higgs mass are both nearly vanishing. Only under these critical conditions can inflation be activated and create a non-empty universe.

    hep-phastro-ph.COhep-thJHEP(2019)·60 citations
19. 19*

    Analytic results for decays of color singlets to $gg$ and $q\bar{q}$ final states at NNLO QCD with the nested soft-collinear subtraction scheme

    Fabrizio Caola🇬🇧 · Kirill Melnikov🇩🇪 · Raoul Röntsch🇨🇭

    We present compact analytic formulas that describe the decay of colorless particles to both $q\bar{q}$ and $gg$ final states through next-to-next-to-leading order in perturbative QCD in the context of the nested soft-collinear subtraction scheme. In addition to their relevance for the description of decays like $V\to q{\bar{q}}^{\prime }$, $V=Z,W$, $H\to b\bar{b}$ and $H\to gg$, these results provide an important building block for calculating NNLO QCD corrections to arbitrary processes at colliders within the nested soft-collinear subtraction scheme.

    hep-phEPJC(2019)·50 citations
20. 20*

    Scattering amplitudes and contour deformations

    Gernot Eichmann🇵🇹 · Pedro Duarte🇵🇹 · M. T. Peña🇵🇹 · Alfred Stadler🇵🇹

    We employ a scalar model to exemplify the use of contour deformations when solving Lorentz-invariant integral equations for scattering amplitudes. In particular, we calculate the onshell 2 -> 2 scattering amplitude for the scalar system. The integrals produce branch cuts in the complex plane of the integrand which prohibit a naive Euclidean integration path. By employing contour deformations, we can also access the kinematical regions associated with the scattering amplitude in Minkowski space. We show that in principle a homogeneous Bethe-Salpeter equation, together with analytic continuation methods such as the Resonances-via-Padé method, is sufficient to determine the resonance pole locations on the second Riemann sheet. However, the scalar model investigated here does not produce resonance poles above threshold but instead virtual states on the real axis of the second sheet, which pose difficulties for analytic continuation methods. To address this, we calculate the scattering amplitude on the second sheet directly using the two-body unitarity relation which follows from the scattering equation.

    hep-phhep-thnucl-thPRD(2019)·42 citations
21. 21*

    Cosmological Constraints on Invisible Neutrino Decays Revisited

    Miguel Escudero🇬🇧 · Malcolm Fairbairn🇬🇧

    Invisible neutrino decay modes are difficult to target at laboratory experiments, and current bounds on such decays from solar neutrino and neutrino oscillation experiments are somewhat weak. It has been known for some time that Cosmology can serve as a powerful probe of invisible neutrino decays. In this work, we show that in order for Big Bang Nucleosynthesis to be successful, the invisible neutrino decay lifetime is bounded to be ${\tau }_{\nu }>10^{-3}\text{s}$ at 95\% CL. We revisit Cosmic Microwave Background constraints on invisible neutrino decays, and by using Planck2018 observations we find the following bound on the neutrino lifetime: ${\tau }_{\nu }>(1.3-0.3)\times 10^9\text{s}{\left(m_{\nu }/0.05\text{eV}\right)}^3$ at $95\%$ CL. We show that this bound is robust to modifications of the cosmological model, in particular that it is independent of the presence of dark radiation. We find that lifetimes relevant for Supernova observations (${\tau }_{\nu }\sim 10^5\text{s}{\left(m_{\nu }/0.05\text{eV}\right)}^3$) are disfavoured at more than $5\sigma$ with respect to $\Lambda$CDM given the latest Planck CMB observations. Finally, we show that when including high-$\ell$ Planck polarization data, neutrino lifetimes ${\tau }_{\nu }=(2-16)\times 10^9\text{s}{\left(m_{\nu }/0.05\text{eV}\right)}^3$ are mildly preferred -- with a 1-2 $\sigma$ significance -- over neutrinos being stable.

    hep-phastro-ph.COhep-exPRD(2019)·88 citations
22. 22*

    Particle Ratios within EPOS, UrQMD and Thermal Models at AGS, SPS and RHIC Energies

    Mahmoud Hanafy (Benha U. and WLCAPP, Cairo)🇪🇬 · Abdel Nasser Tawfik (Nile U., ECTP and Johann Wolfgang Goethe-Universitat)🇪🇬 · Muhammad Maher (Helwan U. and WLCAPP, Cairo)🇪🇬 · Werner Scheinast (LHEP JINR, Dubna)🇷🇺

    The particle ratios $k^{+}/{\pi }^{+}$, ${\pi }^{-}/K^{-}$, $\bar{p}/{\pi }^{-}$, $\Lambda /{\pi }^{-}$, $\Omega /{\pi }^{-}$, $p/{\pi }^{+}$, ${\pi }^{-}/{\pi }^{+}$, $K^{-}/K^{+}$, $\bar{p}/p$, $\bar{\Lambda }/\Lambda$, $\bar{\Sigma }/\Sigma$, $\bar{\Omega }/\Omega$ measured at AGS, SPS and RHIC energies are compared with large statistical ensembles of $100,000$ events deduced from the CRMC EPOS $1.99$ and the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) hybrid model. In the UrQMD hybrid model two types of phase transitions are taken into account. All these are then confronted to the Hadron Resonance Gas Model. The two types of phase transitions are apparently indistinguishable. Apart from $k^{+}/{\pi }^{+}$, $k^{-}/{\pi }^{-}$, $\Omega /{\pi }^{-}$, $\bar{p}/{\pi }^{+}$, and $\bar{\Omega }/\Omega$, the UrQMD hybrid model agrees well with the CRMC EPOS $1.99$. Also, we conclude that the CRMC EPOS $1.99$ seems to largely underestimate $k^{+}/{\pi }^{+}$, $k^{-}/{\pi }^{-}$, $\Omega /{\pi }^{-}$, and $\bar{p}/{\pi }^{+}$.

    hep-phhep-exnucl-thIJMPE(2021)·1 citation
23. 23*

    Neutral and charged pion properties under strong magnetic fields in the NJL model

    M. Coppola🇦🇷 · D. Gomez Dumm🇦🇷 · S. Noguera🇪🇸 · N.N. Scoccola🇦🇷

    In the framework of the Nambu--Jona-Lasino (NJL) model, we study the effect of an intense external uniform magnetic field on neutral and charged pion masses and decay form factors. In particular, the treatment of charged pions is carried out on the basis of the Ritus eigenfunction approach to magnetized relativistic systems. Our analysis shows that in the presence of the magnetic field three and four nonvanishing pion-to-vacuum hadronic form factors can be obtained for the case of the neutral and charged pions, respectively. As expected, it is seen that for nonzero magnetic field the ${\pi }^0$ meson can still be treated as a pseudo Nambu-Goldstone boson, and consequently the corresponding form factors are shown to satisfy various chiral relations. For definite parametrizations of the model, numerical results for ${\pi }^0$ and ${\pi }^{\pm }$ masses and decay constants are obtained and compared with previous calculations given in the literature.

    hep-phPRD(2019)·59 citations
24. 24*

    MiniBooNE-DM: a dark matter search in a proton beam dump

    Alexis A. Aguilar-Arevalo (for the MiniBooNE-DM Collaboration)🇲🇽

    In a dedicated run where protons from the Fermilab Booster were delivered directly to the steel beam dump of the Booster Neutrino Beamline (BNB), the MiniBooNE detector was used to search for the production of sub-GeV dark matter particles via vector-boson mediators. The signal searched for was the elastic scattering of dark matter particles off nucleons in the detector mineral oil, with neutrinos being an irreducible background. A review of the experiment, its analysis methods, its results and future perspectives are summarized, demonstrating that beam dump experiments provide a novel and promising approach to dark matter searches. This contribution was written for the TAUP 2017 proceedings.

    ↳ hep-exhep-phJ.Phys.Conf.Ser.(2020)·5 citations
25. 25*

    Duration of Classicality of an inhomogeneous quantum field with repulsive contact self-interactions

    Ariel Arza🇺🇸 · Sankha S. Chakrabarty🇺🇸 · Seishi Enomoto🇺🇸 · Yaqi Han🇺🇸 · Elisa Todarello🇺🇸

    Quantum fields with large degeneracy are often approximated as classical fields. Here, we show how quantum and classical evolution of a highly degenerate quantum field with repulsive contact self-interactions differ from each other. Initially, the field is taken to be homogeneous except for a small plane wave perturbations in only one mode. In quantum field theory, modes satisfying both momentum and energy conservation of the quasi-particles, grow exponentially with time. However, in the classical field approximation, the system is stable. We calculate the time scale after which the classical field description becomes invalid.

    ↳ hep-thhep-phPRD(2019)·4 citations
26. 26*

    Comparison between DAMA/LIBRA and COSINE-100 in the light of Quenching Factors

    Y. J. Ko🇰🇷 · K. W. Kim🇰🇷 · G. Adhikari🇰🇷 · P. Adhikari🇰🇷 · E. Barbosa de Souza🇺🇸 · N. Carlin🇧🇷 · J. J. Choi🇰🇷 · S. Choi🇰🇷 · M. Djamal🇮🇩 · A. C. Ezeribe🇬🇧 · C. Ha🇰🇷 · I. S. Hahn🇰🇷 and 37 other authors

    There is a long standing debate about whether or not the annual modulation signal reported by the DAMA/LIBRA collaboration is induced by Weakly Interacting Massive Particles~(WIMP) in the galaxy's dark matter halo scattering from nuclides in their NaI(Tl) crystal target/detector. This is because regions of WIMP-mass vs. WIMP-nucleon cross-section parameter space that can accommodate the DAMA/LIBRA-phase1 modulation signal in the context of the standard WIMP dark matter galactic halo and isospin-conserving~(canonical), spin-independent~(SI) WIMP-nucleon interactions have been excluded by many of other dark matter search experiments including COSINE-100, which uses the same NaI(Tl) target/detector material. Moreover, the recently released DAMA/LIBRA-phase2 results are inconsistent with an interpretation as WIMP-nuclide scattering via the canonical SI interaction and prefer, instead, isospin-violating or spin-dependent interactions. Dark matter interpretations of the DAMA/LIBRA signal are sensitive to the NaI(Tl) scintillation efficiency for nuclear recoils, which is characterized by so-called quenching factors~(QF), and the QF values used in previous studies differ significantly from recently reported measurements, which may have led to incorrect interpretations of the DAMA/LIBRA signal. In this article, the compatibility of the DAMA/LIBRA and COSINE-100 results, in light of the new QF measurements is examined for different possible types of WIMP-nucleon interactions. The resulting allowed parameter space regions associated with the DAMA/LIBRA signal are explicitly compared with 90\% confidence level upper limits from the initial 59.5~day COSINE-100 exposure. With the newly measured QF values, the allowed 3$\sigma$ regions from the DAMA/LIBRA data are still generally excluded by the COSINE-100 data.

    ↳ hep-exastro-ph.IMhep-phphysics.ins-detJCAP(2019)·31 citations
27. 27*

    Einstein's Equations in Matter

    Pavel Kovtun🇨🇦 · Ashish Shukla🇨🇦

    Einstein's equations in matter are gravitational analogues of Maxwell's equations in matter, providing an effective classical description of gravitational fields. We derive Einstein's equations in matter for relativistic fluids, and use them to illustrate how the Tolman-Oppenheimer-Volkoff equations are modified by the matter's response to curvature. For a gas of massive fermions, we evaluate how the effective Newton's constant and other susceptibilities depend on the temperature and density. In anti-de Sitter space, we study the $O(1/(T\ell {)}^2)$ corrections to the geometries sourced by perfect fluids, and illustrate the breakdown of hydrostatics in AdS at small temperatures.

    ↳ gr-qchep-phhep-thPRD(2020)·11 citations
28. 28*

    Forecasts of redshift drift constraints on cosmological parameters

    C. S. Alves🇵🇹 · A. C. O. Leite🇵🇹 · C. J. A. P. Martins🇵🇹 · J. G. B. Matos🇵🇹 · T. A. Silva🇵🇹

    Cosmological observations usually map our present-day past light cone. However, it is also possible to compare different past light cones. This is the concept behind the redshift drift, a model-independent probe of fundamental cosmology. In simple physical terms, this effectively allows us to watch the Universe expand in real time. While current facilities only allow sensitivities several orders of magnitude worse than the expected signal, it should be possible to detect it with forthcoming ones. Here we discuss the potential impact of measurements by three such facilities: the Extremely Large Telescope (the subject of most existing redshift drift forecasts), but also the Square Kilometre Array and intensity mapping experiments. For each of these we assume the measurement sensitivities estimated respectively in Liske {\it et al.} (2008), Klockner {\it et al.} (2015) and Yu {\it et al.} (2014). We focus on the role of these measurements in constraining dark energy scenarios, highlighting the fact that although on their own they yield comparatively weak constraints, they do probe regions of parameter space that are typically different from those probed by other experiments, as well as being redshift-dependent. Specifically, we quantify how combinations of several redshift drift measurements at different redshifts, or combinations of redshift drift measurements with those from other canonical cosmological probes, can constrain some representative dark energy models. Our conclusion is that a model-independent mapping of the expansion of the universe from redshift $z=0$ to $z=4$---a challenging but feasible goal for the next generation of astrophysical facilities---can have a significant impact on fundamental cosmology.

    ↳ astro-ph.COgr-qchep-phMNRAS(2019)·39 citations
29. 29*

    Low-frequency Gravitational Waves from Double-inflection-point Inflation

    Wu-Tao Xu🇨🇳 · Jing Liu🇨🇳 · Tie-Jun Gao🇨🇳 · Zong-Kuan Guo🇨🇳

    We study the production of gravitational waves from primordial scalar perturbations in double-inflection-point inflation, in which one of the inflection points predicts the power spectra consistent with CMB observations at large scales and the other generates a large peak in the power spectrum of scalar perturbations at small scales. We find that the reduced gravitational waves at low frequencies can be detected by future space-based laser interferometers.

    ↳ astro-ph.COgr-qchep-phPRD(2020)·100 citations
30. 30*

    Dissecting the growth of the power spectrum for primordial black holes

    Pedro Carrilho🇬🇧 · Karim A. Malik🇬🇧 · David J. Mulryne🇬🇧

    We consider the steepest rate at which the power spectrum from single field inflation can grow, with the aim of providing a simple explanation for the $k^4$ growth found recently. With this explanation in hand we show that a slightly steeper $k^5(\log k{)}^2$ growth is in fact possible. Moreover, we argue that the power spectrum after a steep growth cannot immediately decay, but must remain large for the $k$ modes which exit during a $\sim 2$ e-fold period. We also briefly consider how a strong growth can affect the spectral index of longer wavelengths preceding the growth, and show that even the conversion of isocurvature modes likely cannot lead to a stronger growth. These results have implications for the formation of primordial black holes, and other phenomena which require a large amplitude of power spectrum at short scales.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2019)·124 citations
31. 31*

    Towards implications of asymptotically safe gravity for particle physics

    Astrid Eichhorn🇩🇰 · Aaron Held🇩🇪

    We review aspects of the interplay of asymptotically safe gravity with matter, focusing on the potential predictive power of the quantum scale-symmetry underlying the asymptotically safe fixed point. We explain how an asymptotically safe fixed point for the Standard Model, induced by quantum-gravity fluctuations, might i) render the Standard Model ultraviolet complete and ii) allow us to calculate the values of some of the Standard-Model couplings. In particular, we highlight that such a fixed point might explain the mass-difference between the top and bottom quark.

    ↳ hep-thgr-qchep-phPoS(2020)·7 citations
32. 32*

    Non-Gaussian CMB and LSS statistics beyond polyspectra

    Gonzalo A. Palma🇨🇱 · Bruno Scheihing Hitschfeld🇨🇱 · Spyros Sypsas🇨🇱

    Cosmic inflation may have led to non-Gaussian initial conditions that cannot be fully parametrised by 3- and/or 4-point functions. In this work, we discuss various strategies to search for primordial non-Gaussianity beyond polyspectra with the help of cosmological data. Our starting point is a generalised local ansatz for the primordial curvature perturbation $\zeta$ of the form $\zeta ={\zeta }_{\mathrm{G}}+{\mathcal{F}}_{\mathrm{NG}}({\zeta }_{\mathrm{G}})$, where ${\zeta }_{\mathrm{G}}$ is a Gaussian random field and ${\mathcal{F}}_{\mathrm{NG}}$ is an arbitrary function parametrising non-Gaussianity that, in principle, could be reconstructed from data. Noteworthily, in the case of multi-field inflation, the function ${\mathcal{F}}_{\mathrm{NG}}$ can be shown to be determined by the shape of tomographic sections of the landscape potential responsible for driving inflation. We discuss how this generalised local ansatz leads to a probability distribution functional that may be used to extract information about inflation from current and future observations. In particular, we derive various classes of probability distribution functions suitable for the statistical analysis of the cosmic microwave background and large-scale structure.

    ↳ astro-ph.COhep-phhep-thJCAP(2020)·15 citations
33. 33*

    Phases of Hadron-Quark Matter in (Proto) Neutron Stars

    F. Weber (1 and 2) · D. Farrell (1) · W. M. Spinella (3) · G. Malfatti (4 and 5) · M. G. Orsaria (4 and 5) · G. A. Contrera (4 and 6) · I. Maloney (1) ((1) San Diego State University, (2) University of California at San Diego, (3) Wentworth Institute of Technology, (4) National University of La Plata, (5) CONICET (National Scientific and Technical Research Council, Argentina))

    In the first part of this paper, we investigate the possible existence of a structured hadron-quark mixed phase in the cores of neutron stars. This phase, referred to as the hadron-quark pasta phase, consists of spherical blob, rod, and slab rare phase geometries. Particular emphasis is given to modeling the size othis phase in rotating neutron stars. We use the relativistic mean-field theory to model hadronic matter and the non-local three-flavor Nambu-Jona-Lasinio model to describe quark matter. Based on these models, the hadron-quark pasta phase exists only in very massive neutron stars, whose rotational frequencies are less than around 300 Hz. All other stars are not dense enough to trigger quark deconfinement in their cores. Part two of the paper deals with the quark-hadron composition of hot (proto) neutron star matter. To this end we use a local three-flavor Polyakov-Nambu-Jona-Lasinio model which includes the 't Hooft (quark flavor mixing) term. It is found that this term leads to non-negligible changes in the particle composition of (proto) neutron stars made of hadron-quark matter.

    ↳ nucl-thastro-ph.HEhep-phUniverse(2019)·18 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.