Mon·Oct 4, 2021Monday·October 4, 2021

1. 01*

   Collinear factorization of diphoton photoproduction at next to leading order

   Oskar Grocholski🇵🇱 · Bernard Pire🇫🇷 · Paweł Sznajder🇵🇱 · Lech Szymanowski🇵🇱 · Jakub Wagner🇵🇱

   We calculate in the framework of collinear factorization the amplitude for the photoproduction of a near forward large mass diphoton at leading twist and next to leading order (NLO) in ${\alpha }_s$. We demonstrate the validity of factorization at this order, which was never achieved for such a reaction where the coefficient function describes a $2\to 3$ hard process. While the Born order amplitude was purely imaginary and only probed the $x=\pm \xi$ cross-over line of generalized parton distributions (GPD) domain, the NLO result contains both a real and an imaginary part and probes the whole domain of definition of quark GPDs. The phenomenology of our results for medium (JLab) and higher energy (EIC) experiments will be developed in a future study.

   hep-phhep-exnucl-exnucl-thPRD(2021)·35 citations
2. 02*

   High-order baryon number fluctuations within the fRG approach

   Wei-jie Fu🇨🇳 · Xiaofeng Luo🇨🇳 · Jan M. Pawlowski🇩🇪 · Fabian Rennecke🇺🇸 · Rui Wen🇨🇳 · Shi Yin🇨🇳

   We compute high-order baryon number fluctuations at finite temperature and density within a QCD-assisted low energy effective field theory. Quantum, thermal and density fluctuations are incorporated with the functional renormalization group approach. Quantum and in-medium fluctuations are encoded via the evolution of renormalization group flow equations. The resulting fourth- and sixth-order baryon number fluctuations meet the lattice benchmark results at vanishing density. They are consistent with experimental measurements, and in particular, the non-monotonic dependence of the kurtosis of net-baryon number distributions on the collision energy is observed in our calculations. This non-monotonicity arises from the increasingly sharpened chiral crossover with the decrease of collision energy.

   hep-phnucl-exnucl-thPoS(2022)·1 citation
3. 03*

   Collective Neutrino Flavor Instability Requires a Crossing

   Basudeb Dasgupta (TIFR)🇮🇳

   Neutrinos in supernovae, neutron stars, and in the early Universe may change flavor collectively and unstably, due to neutrino-neutrino forward-scattering. We prove that for collective instability to occur, the difference of momentum distributions of two flavors must change sign, i.e., there is a zero crossing. This necessary criterion, which unifies slow and fast instabilities, is valid for Hamiltonian flavor-evolution of ultra-relativistic Standard Model neutrino occupation matrices, including damping due to collisions in the relaxation approximation. It provides a simple but rigorous condition for collective flavor transformations that are believed to be important for stellar dynamics, nucleosynthesis, and neutrino phenomenology.

   hep-phastro-ph.COastro-ph.SRhep-thPRL(2022)·86 citations
4. 04*

   Invariant-mass spectrum of $\Lambda \bar{\Lambda }$ pair in the process $e^{+}{e}^{-}\to \varphi \Lambda \bar{\Lambda }$

   A.I. Milstein🇷🇺 · S.G. Salnikov🇷🇺

   We show that the final-state interaction perfectly explains the recent experimental data of BESIII Collaboration on the near-threshold invariant-mass spectrum of $\Lambda \bar{\Lambda }$ in the process $e^{+}{e}^{-}\to \varphi \Lambda \bar{\Lambda }$. The position of peak in invariant-mass spectrum is above the threshold though the interaction of $\Lambda$ and $\bar{\Lambda }$ is due to an attractive potential. This potential has a simple form and depends only on two parameters. We show that the invariant-mass spectrum is consistent with the quantum numbers $J^{PC}=1^{++}$ and $2^{++}$ of $\Lambda \bar{\Lambda }$ pair but contradicts to $J^{PC}=2^{-+}$.

   hep-phhep-exPRD(2022)·8 citations
5. 05*

   Emergent gauge symmetries -- making symmetry as well as breaking it

   Steven D. Bass🇵🇱

   Gauge symmetries play an essential role in determining the interactions of particle physics. Where do they come from? Might the gauge symmetries of the Standard Model unify in the ultraviolet or might they be emergent in the infrared, below some large scale close to the Planck scale? Emergent gauge symmetries are important in quantum many-body systems in quantum phases associated with long range entanglement and topological order, e.g., they arise in high temperature superconductors, with string-net condensation and in the A-phase of superfluid He-3. String-nets and superfluid He-3 exhibit emergent properties similar to the building blocks of particle physics. Emergent gauge symmetries also play an important role in simulations of quantum field theories. This article discusses recent thinking on possible emergent gauge symmetries in particle physics, commenting also on Higgs phenomena and the vacuum energy or cosmological constant puzzle in emergent gauge systems.

   hep-phhep-thquant-phPhil.Trans.Roy.Soc.Lond.A(2021)·11 citations
6. 06*

   Timelike Transition Form Factor for CP-odd Higgs Boson Production

   Ken Sasaki🇯🇵 · Tsuneo Uematsu🇯🇵

   We investigate the production of CP-odd Higgs boson $A^0$ associated with a real $\gamma$ in $e^{+}{e}^{-}$ collisions. Because of the properties of $A^0$ coupling to the other fields, the main contribution comes from the top-quark triangle loop diagrams. We obtain the timelike transition form factor which describes the production amplitude of $A^0$ in the $e^{+}{e}^{-}$ collisions. This timelike transition form factor is related to the spacelike transition form factor relevant for the $A^0$ production in $e^{-}\gamma$ collisions. It turns out that the possible extra contributions from chargino-sneutrino and neutralino-selectron box diagrams do not give sizable effects.

   hep-ph0 citations
7. 07*

   Non-radial oscillation modes in hybrid stars: consequences of a mixed phase

   Deepak Kumar🇮🇳 · Hiranmaya Mishra🇮🇳 · Tuhin Malik🇵🇹

   We study the possibility of the existence of a deconfined quark matter in the core of neutron star (NS)s and its relation to non-radial oscillation modes in NSs and hybrid star (HS)s. We use relativistic mean field (RMF) models to describe the nuclear matter at low densities and zero temperature. The Nambu--Jona-Lasinio (NJL) model is used to describe the quark matter at high densities and zero temperature. A Gibbs construct is used to describe the hadron-quark phase transition (HQPT) at large densities. Within the model, as the density increases, a mixed phase (MP) appears at density about $2.5$ times the nuclear matter saturation density $({\rho }_0)$ and ends at density about $5{\rho }_0$ beyond which the pure quark matter phase appears. It turns out that a stable HS of maximum mass, $M=2.27M_{\odot }$ with radius $R=14$ km (for NL3 parameterisation of nuclear RMF model), can exist with the quark matter in the core in a MP only. HQPT in the core of maximum mass HS occurs at radial distance, $r_c=0.27R$ where the equilibrium speed of sound shows a discontinuity. Existence of quark matter in the core enhances the non-radial oscillation frequencies in HSs compared to NSs of the same mass. This enhancement is significantly large for the $g$ modes. Such an enhancement of the $g$ modes is also seen for a density dependent Bayesian (DDB) parmeterisation of the nucleonic EOS. The non-radial oscillation frequencies depend on the vector coupling in the NJL model. The values of $g$ and $f$ mode frequencies decrease with increase the vector coupling in quark matter.

   hep-phnucl-thJCAP(2023)·33 citations
8. 08*

   Is $Z_{cs}(3982)$ a molecular partner of $Z_c(3900)$ and $Z_c(4020)$ states?

   V. Baru🇩🇪 · E. Epelbaum🇩🇪 · A. A. Filin🇩🇪 · C. Hanhart🇩🇪 · A. V. Nefediev🇷🇺

   We perform an effective-field-theory-based coupled-channel analysis of the recent BES III data on the $e^{+}{e}^{-}$ annihilation into the final state $K^{+}(D_s^{-}{D}^{\ast 0}+D_s^{\ast -}{D}^0)$ in a wide energy range and extract the poles responsible for the formation of the $Z_{cs}(3982)$. We identify two scenarios which provide a similar description of the experimental mass distributions but result in utterly different predictions for the spin partners of the $Z_{cs}(3982)$: although both scenarios are consistent with the $Z_{cs}$ as a $SU(3)$ partner of the $Z_c(3900)$, the $Z_c(4020)$ appears naturally as a spin partner of these states only in one of them (fit 1) while in the other (fit 2) its nature has to be different. Also, the $Z_{cs}(3982)$ has a $J^P=1^{+}$ spin partner near the ${\bar{D}}_s^{\ast }{D}^{\ast }$ threshold in fit 1, while no such state exists in fit 2. We predict the ${\bar{D}}_s^{\ast }{D}^{\ast }$ invariant mass distribution in the $J^P=1^{+}$ channel for the reaction $e^{+}{e}^{-}\to K^{+}{D}_s^{\ast -}{D}^{\ast 0}$ and argue that this line shape can be used to distinguish between the two scenarios once data in this channel are available.

   hep-phhep-exhep-latnucl-thPRD(2022)·36 citations
9. 09*

   How to predict a new physics scale and its uncertainty with the Inverse Amplitude Method

   Alexandre Salas-Bernárdez🇪🇸

   Effective Field Theories such as HEFT, organized as momentum expansions, are a controllable approximation to strong dynamics only near threshold, as they miss exact elastic unitarity, reducing their predictive power at a higher scale if small separations from the Standard Model are found at the LHC or elsewhere. Unitarized chiral perturbation theory extends their reach to the saturation of unitarity but, generally with unknown systematics. Here I present a brief "handbook" on how to put to use the Inverse Amplitude Method to predict a resonance (associated with a new physics scale in Beyond the Standard Model searches) and more especially on how to control its systematic uncertainties.

   hep-phPoS(2022)·1 citation
10. 10*

    LHC bounds on MUED after Run 2

    Marvin M. Flores🇿🇦 · Jong Soo Kim🇿🇦 · Krzysztof Rolbiecki🇵🇱 · Roberto Ruiz de Austri Bazan🇪🇸

    We present updated LHC limits on the minimal universal extra dimensions (MUED) model from the Run 2 searches. We scan the parameter space against a number of searches implemented in the public code \textsc{CheckMATE} and derive up-to-date limits on the MUED parameter space from 13 TeV searches. The strongest constraints come from a search dedicated to squarks and gluinos with one isolated lepton, jets and missing transverse energy. In the procedure we take into account initial state radiation and stress its importance in the MUED searches, which is not always appreciated.

    hep-phInt.J.Mod.Phys.A(2023)·4 citations
11. 11*

    Spontaneously stabilised dark matter from a fermiophobic $U(1{)}^{\prime }$ gauge symmetry

    Bowen Fu🇬🇧 · Stephen F. King🇬🇧

    We consider the possibility that dark matter is stabilised by a discrete $Z_2$ symmetry which arises from a subgroup of a $U(1{)}^{\prime }$ gauge symmetry, spontaneously broken by integer charged scalars, and under which the chiral quarks and leptons do not carry any charges. A chiral fermion $\chi$ with half-integer charge is odd under the preserved $Z_2$, and hence becomes a stable dark matter candidate, being produced through couplings to right-handed neutrinos with vector-like $U(1{)}^{\prime }$ charges, as in the type Ib seesaw mechanism. We calculate the relic abundance in such a low energy effective seesaw model containing few parameters, then consider a high energy renormalisable model with a complete fourth family of vector-like fermions, where the chiral quark and lepton masses arise from a seesaw-like mechanism. With the inclusion of the fourth family, the lightest vector-like quark can contribute to the dark matter production, enlarging the allowed parameter space that we explore.

    hep-phJHEP(2021)·8 citations
12. 12*

    Core-collapse, evaporation and tidal effects: the life story of a self-interacting dark matter subhalo

    Zhichao Carton Zeng🇺🇸 · Annika H. G. Peter🇺🇸 · Xiaolong Du🇺🇸 · Andrew Benson🇺🇸 · Stacy Kim🇬🇧 · Fangzhou Jiang🇺🇸 · Francis-Yan Cyr-Racine🇺🇸 · Mark Vogelsberger🇺🇸

    Self-interacting dark matter (SIDM) cosmologies admit an enormous diversity of dark matter (DM) halo density profiles, from low-density cores to high-density core-collapsed cusps. The possibility of the growth of high central density in low-mass halos, accelerated if halos are subhalos of larger systems, has intriguing consequences for small-halo searches with substructure lensing. However, following the evolution of $\lesssim 10^8{M}_{\odot }$ subhalos in lens-mass systems ($\sim 10^{13}{M}_{\odot }$) is computationally expensive with traditional N-body simulations. In this work, we develop a new hybrid semi-analytical + N-body method to study the evolution of SIDM subhalos with high fidelity, from core formation to core-collapse, in staged simulations. Our method works best for small subhalos ($\lesssim 1/1000$ host mass), for which the error caused by dynamical friction is minimal. We are able to capture the evaporation of subhalo particles by interactions with host halo particles, an effect that has not yet been fully explored in the context of subhalo core-collapse. We find three main processes drive subhalo evolution: subhalo internal heat outflow, host-subhalo evaporation, and tidal effects. The subhalo central density grows only when the heat outflow outweighs the energy gain from evaporation and tidal heating. Thus, evaporation delays or even disrupts subhalo core-collapse. We map out the parameter space for subhalos to core-collapse, finding that it is nearly impossible to drive core-collapse in subhalos in SIDM models with constant cross sections. Any discovery of ultra-compact dark substructures with future substructure lensing observations favors additional degrees of freedom, such as velocity-dependence, in the cross section.

    ↳ astro-ph.COastro-ph.GAhep-phMNRAS(2022)·101 citations
13. 13*

    Constraints on high density equation of state from maximum neutron star mass

    Márcio Ferreira🇵🇹 · Constança Providência🇵🇹

    The low density nuclear matter equation of state is strongly constrained by nuclear properties, however, for constraining the high density equation of state it is necessary to resort to indirect information obtained from the observation of neutron stars, compact objects that may have a central density several times nuclear matter saturation density, $n_0$. Taking a meta-modelling approach to generate a huge set of equation of state that satisfy nuclear matter properties close to $n_0$ and that do not contain a first order phase transition, the possibility of constraining the high density equation of state was investigated. The entire information obtained from the GW170817 event for the probability distribution of $\tilde{\Lambda }$ was used to make a probabilistic inference of the EOS, which goes beyond the constraints imposed by nuclear matter properties. Nuclear matter properties close to saturation, below $2n_0$, do not allow us to distinguish between equations of state that predict different neutron star (NS) maximum masses. This is, however, not true if the equation of state is constrained at low densities by the tidal deformability of the NS merger associated to GW170817. Above $3n_0$, differences may be large, for both approaches, and, in particular, the pressure and speed of sound of the sets studied do not overlap, showing that the knowledge of the NS maximum mass may give important information on the high density EOS. Narrowing the maximum mass uncertainty interval will have a sizeable effect on constraining the high density EOS.

    ↳ nucl-thastro-ph.HEhep-phPRD(2021)·34 citations
14. 14*

    Cosmological forecasts on thermal axions, relic neutrinos and light elements

    William Giarè🇮🇹 · Fabrizio Renzi🇳🇱 · Alessandro Melchiorri🇮🇹 · Olga Mena🇪🇸 · Eleonora Di Valentino🇬🇧

    One of the targets of future Cosmic Microwave Background and Baryon Acoustic Oscillation measurements is to improve the current accuracy in the neutrino sector and reach a much better sensitivity on extra dark radiation in the Early Universe. In this paper we study how these improvements can be translated into constraining power for well motivated extensions of the Standard Model of elementary particles that involve axions thermalized before the quantum chromodynamics (QCD) phase transition by scatterings with gluons. Assuming a fiducial $\Lambda$CDM cosmological model, we simulate future data for Stage-IV CMB-like and Dark Energy Spectroscopic Instrument (DESI)-like surveys and analyze a mixed scenario of axion and neutrino hot dark matter. We further account also for the effects of these QCD axions on the light element abundances predicted by Big Bang Nucleosynthesis. The most constraining forecasted limits on the hot relic masses are $m_{\mathrm{a}}\lesssim 0.92$ eV and $\sum m_{\nu }\lesssim 0.12$ eV at 95 per cent Confidence Level, showing that future cosmic observations can substantially improve the current bounds, supporting multi-messenger analyses of axion, neutrino and primordial light element properties.

    ↳ astro-ph.COhep-phMNRAS(2022)·22 citations
15. 15*

    Energy spectra of secondaries in proton-proton interactions

    S. Koldobskiy🇷🇺 · M. Kachelrieß🇳🇴 · A. Lskavyan🇷🇺 · A. Neronov🇫🇷 · S. Ostapchenko🇩🇪 · D. V. Semikoz🇫🇷

    We compare the predictions of AAfrag for the spectra of secondary photons, neutrinos, electrons, and positrons produced in proton-proton collisions to those of the parameterisations of Kamae et al., Kelner et al., and Kafexhiu et al. We find that the differences in the normalisation of the photon energy spectra reach 20$-$50% at intermediate values of the transferred energy fraction $x$, growing up to a factor of two for $x\to$1, while the differences in the neutrino spectra are even larger. We argue that LHCf results on the forward production of photons favor the use of the QGSJET-II-04m model on which AAfrag is based. The differences in the normalisation have important implications in the context of multi-messenger astronomy, in particular, for the prediction of neutrino fluxes based on gamma-ray flux measurements, or regarding the inference of the cosmic ray spectrum, based on gamma-ray data. We note also that the positron-electron ratio from hadronic interactions increases with energy towards the cutoff, an effect which is missed using the average electron-positron spectrum from Kelner et al. Finally, we describe the publicly available python package aafragpy, which provides the secondary spectra of photons, neutrinos, electrons, and positrons. This package complements the AAfrag results for protons with energies above 4 GeV with previous analytical parameterizations of particle spectra for lower energy protons.

    ↳ astro-ph.HEhep-phPRD(2021)·73 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.