Fri·Jul 7, 2023Friday·July 7, 2023

1. 01*

   Heavy neutral lepton corrections to SM boson decays: lepton flavour universality violation in low-scale seesaw realisations

   A. Abada🇫🇷 · J. Kriewald🇸🇮 · E. Pinsard🇫🇷 · S. Rosauro-Alcaraz🇫🇷 · A. M. Teixeira🇫🇷

   We study lepton flavour universality violation in SM boson decays in low-scale seesaw models of neutrino mass generation, also addressing other electroweak precision observables. We compute the electroweak next-to-leading order corrections, which turn out to be important - notably in the case of the invisible decay width of the $Z$ boson, for which the corrections can be as large as the current experimental uncertainty. As a well-motivated illustrative study case, we choose a realisation of the Inverse Seesaw mechanism, and discuss the complementary role of lepton flavour conserving, lepton flavour violating and precision observables, both in constraining and in probing such models of neutrino mass generation. Our findings suggest that invisible $Z$ decays are especially important, potentially at the origin of the most stringent constraints for certain regimes of the Inverse Seesaw (while complying with charge lepton flavour violation and other electroweak precision tests). We also discuss the probing power of the considered observables in view of the expected improvement in experimental precision at FCC-ee.

   hep-phEPJC(2024)·11 citations
2. 02*

   Matter-antimatter asymmetry and dark matter stability from baryon number conservation

   Mar Císcar-Monsalvatje🇩🇪 · Alejandro Ibarra🇩🇪 · Jérôme Vandecasteele🇩🇪

   There is currently no evidence for a baryon asymmetry in our Universe. Instead, cosmological observations have only demonstrated the existence of a quark-antiquark asymmetry, which does not necessarily imply a baryon asymmetric Universe, since the baryon number of the dark sector particles is unknown. In this paper we discuss a framework where the total baryon number of the Universe is equal to zero, and where the observed quark-antiquark asymmetry arises from neutron portal interactions with a dark sector fermion $N$ that carries baryon number. In order to render a baryon symmetric universe throughout the whole cosmological history, we introduce a complex scalar $\chi$, with opposite baryon number and with the same initial abundance as $N$. Notably, due to the baryon number conservation, $\chi$ is absolutely stable and could have an abundance today equal to the observed dark matter abundance. Therefore, in this simple framework, the existence of a quark-antiquark asymmetry is intimately related to the existence (and the stability) of dark matter.

   hep-phJCAP(2024)·9 citations
3. 03*

   The Postdoc Accord in Theoretical High Energy Physics

   Djuna Croon · Patrick J. Fox · Roni Harnik · Simon Knapen · Mariangela Lisanti · Lina Necib · Tien-Tien Yu

   We present the results of a survey meant to assess the opinion of the high-energy physics theory (HET) community on the January 7th postdoc acceptance deadline - specifically, whether there is a preference to shift the deadline to later in January or February. This survey, which served for information-gathering purpose only, is part of a community conversation on the optimal timing of an acceptance deadline and whether the community would be better served by a later date. In addition, we present an analysis of data from the postdoc Rumor Mill, which gives a picture of the current hiring landscape in the field. We emphasize the importance of preserving a universal deadline, and the current results of our survey show broad support for a shift to a later date. A link to the survey, frequently asked questions, a running list of supporters, and next steps can be found on our companion web page.

   hep-phgr-qchep-lathep-th0 citations
4. 04*

   Heavy flavor conserved semi-leptonic decay of $B_s$ in the covariant light-front approach

   Yu-Ji Shi🇨🇳 · Zhi-Peng Xing🇨🇳

   We study the heavy flavor conserved semi-leptonic decay $B_s\to B\ell \nu$ in the covariant light front approach. The covariant light front quark model is used to calculate the transition form factors of $B_s\to B^{(\ast )}$ as well as $D_s\to D$, which are consistent with the leading power predictions from the heavy quark symmetry. The angular distribution analysis on the $B_s\to B^{(\ast )}l\bar{\nu }$ decay is performed by investigating the forward-backward asymmetry of the lepton. We also study the angular distribution of $B_s\to B^{\ast }(\to B\gamma )l\bar{\nu }$ decay both through the lepton forward-backward asymmetry and the azimuth angle. The branching fractions of $B_s\to Bl\bar{\nu }$ and $B_s\to B^{\ast }l\bar{\nu }$ are at the order $10^{-8}$ and $10^{-9}$, respectively. The number of $B_s\to Bl\bar{\nu }$ events is estimated to be $1.76$. The branching fraction of $B_s\to B^{\ast }(\to B\gamma )l\bar{\nu }$ is at the order $10^{-11}$, which is calculated by introducing Breit-Wigner distribution for the intermediate $B^{\ast }$.

   hep-phhep-exNPB(2024)·4 citations
5. 05*

   $J/\psi$ Pair Hadroproduction at Next-to-Leading Order in Nonrelativistic-QCD at CMS

   Liping Sun🇨🇳

   We perform a complete study on the $J/\psi$ pair hadroproduction at next-to-leading order (NLO) in the nonrelativstic-QCD (NRQCD) framework with the pair of $c\bar{c}$ either in ${}^3{S}_1^{[1]}$ or ${}^1{S}_0^{[8]}$ fock state. It is found that the ${}^1{S}_0^{[8]}$ channel contribution at NLO is essential. Our results indicate that for the CMS, the NRQCD predictions can not describe the experimental data at all, and the total cross section predicted by NRQCD is smaller than the experimental data by an order of magnitude. So new mechanisms are needed to understand the CMS data for $J/\psi$ pair production.

   hep-phCPC(2024)·7 citations
6. 06*

   Several Topics on Transverse Momentum-Dependent Fragmentation Functions

   Kai-Bao Chen🇨🇳 · Tianbo Liu🇨🇳 · Yu-Kun Song🇨🇳 · Shu-Yi Wei🇨🇳

   The hadronization of a high-energy parton is described by fragmentation functions which are introduced through QCD factorizations. While the hadronization mechanism per se remains uknown, fragmentation functions can still be investigated qualitatively and quantitatively. The qualitative study mainly concentrates on extracting genuine features based on the operator definition in quantum field theory. The quantitative research focuses on describing a variety of experimental data employing the fragmentation function given by the parameterizations or model calculations. With the foundation of the transverse-momentum-dependent factorization, the QCD evolution of leading twist transverse-momentum-dependent fragmentation functions has also been established. In addition, the universality of fragmentation functions has been proven, albeit model-dependently, so that it is possible to perform a global analysis of experimental data in different high-energy reactions. The collective efforts may eventually reveal important information hidden in the shadow of nonperturbative physics. This review covers the following topics: transverse-momentum-dependent factorization and the corresponding QCD evolution, spin-dependent fragmentation functions at leading and higher twists, several experimental measurements and corresponding phenomenological studies, and some model calculations.

   hep-phParticles(2023)·18 citations
7. 07*

   Pion PDFs confronted by Fixed-Target Charmonium Production

   Wen-Chen Chang🇹🇼 · Chia-Yu Hsieh🇹🇼 · Yu-Shiang Lian🇹🇼 · Jen-Chieh Peng🇺🇸 · Stephane Platchkov🇫🇷 · Takahiro Sawada🇯🇵

   The pion, as the Goldstone boson of the strong interaction, is the lightest QCD bound state and responsible for the long-range nucleon-nucleon interaction inside the nucleus. Our knowledge on the pion partonic structure is limited by the existing Drell-Yan data which are primarily sensitive to the pion valence-quark distributions. The recent progress of global analysis of pion's parton distribution functions (PDFs) utilizing various experimental approaches are introduced. From comparisons between the pion-induced $J/\psi$ and $\psi (2S)$ production data with theoretical calculations using the CEM and NRQCD models, we show how these charmonium production data could provide useful constraints on the pion PDFs.

   hep-phhep-exnucl-exAAPPS Bull.(2023)·2 citations
8. 08*

   Did the nHZ Gravitational Waves Signatures Observed By NANOGrav Indicate Multiple Sector SUSY Breaking?

   Xiao Kang Du🇨🇳 · Ming Xia Huang🇨🇳 · Fei Wang🇨🇳 · Ying Kai Zhang🇨🇳

   Discrete R symmetries always play an important role in low energy SUSY. The spontaneously broken of such discrete R symmetries, for example, by gaugino condensation, can lead to domain walls, which need to be either inflated away or collapse to avoid cosmic difficulties. We propose that explicitly R symmetry violation needed for collapse of domain walls can be the consequence of multiple sector SUSY breaking. The consistency constraints for the generation of non-problematic domain walls from gaugino condensation are discussed. We also study the emitted gravitational waves related to the collapse of domain walls. We find that, for SUSY breaking scale of order $\mathcal{O}(1)$ $\mathrm{GeV}$ in one of the sequestered sector (and also a low reheating temperature of order $\mathrm{MeV}$ if the reheating is not completed when the domain walls collapse), the peak frequency of gravitational waves emitted can lie at nHz. Such a low SUSY breaking scale can be consistency and natural in multiple sector SUSY breaking scenario. The GWs signal by NANOGrav could be a signal of such multiple sector SUSY breaking scenario and it may also indicate the existences of light goldstini at $\mathrm{eV}$ mass scale.

   hep-phhep-th48 citations
9. 09*

   Analytic results on the massive three-loop form factors: quarkonic contributions

   Johannes Blümlein🇩🇪 · Abilio De Freitas🇦🇹 · Peter Marquard🇩🇪 · Narayan Rana🇮🇳 · Carsten Schneider🇦🇹

   The quarkonic contributions to the three-loop heavy-quark form factors for vector, axial-vector, scalar and pseudoscalar currents are described by closed form difference equations for the expansion coefficients in the limit of small virtualities $q^2/m^2$. A part of the contributions can be solved analytically and expressed in terms of harmonic and cyclotomic harmonic polylogarithms and square-root valued iterated integrals. Other contributions obey equations which are not first-order factorizable. For them still infinite series expansions around the singularities of the form factors can be obtained by matching the expansions at intermediate points and using differential equations which are obeyed directly by the form factors and are derived by guessing algorithms. One may determine all expansion coefficients for $q^2/m^2\to \infty$ analytically in terms of multiple zeta values. By expanding around the threshold and pseudo-threshold, the corresponding constants are multiple zeta values supplemented by a finite amount of new constants, which can be computed at high precision. For a part of these coefficients, the infinite series in front of these constants may be even resummed into harmonic polylogarithms. In this way, one obtains a deeper analytic description of the massive form factors, beyond their pure numerical evaluation. The calculations of these analytic results are based on sophisticated computer algebra techniques. We also compare our results with numerical results in the literature.

   hep-phmath-phmath.MPPRD(2023)·17 citations
10. 10*

    The $D_s^{+}\to K^{+}{\pi }^{+}{\pi }^{-}$ reaction and the scalar $f_0(500)$, $f_0(980)$ and $K_0^{\ast }(700)$ resonances

    L. R. Dai🇨🇳 · E. Oset🇪🇸

    We develop a model to reproduce the mass distributions of pairs of mesons in the Cabibbo-suppressed $D_s^{+}\to K^{+}{\pi }^{+}{\pi }^{-}$ decay. The largest contributions to the process comes from the $D_s^{+}\to K^{+}{\rho }^0$ and $D_s^{+}\to K^{\ast 0}{\pi }^{+}$ decay modes, but the $D_s^{+}\to K_0^{\ast }(1430){\pi }^{+}$ and $D_s^{+}\to K^{+}{f}_0(1370)$ modes also play a moderate role and all of them are introduced empirically. Instead, the contribution of the $f_0(500)$, $f_0(980)$ and $K_0^{\ast }(700)$ resonances is introduced dynamically by looking at the decay modes at the quark level, hadronizing $q\bar{q}$ pairs to give two mesons, and allowing these mesons to interact to finally produce the $K^{+}{\pi }^{+}{\pi }^{-}$ final state. These last three modes are correlated by means of only one parameter. We obtain a fair reproduction of the experimental data for the three mass distributions as well as the relative weight of the three light scalar mesons, which we see as further support for the nature of these states as dynamically generated from the interaction of pseudoscalar mesons.

    hep-phPRD(2024)·9 citations
11. 11*

    Quarkyonic matter and quarkyonic stars in an extended RMF model

    Cheng-Jun Xia🇨🇳 · Hao-Miao Jin🇨🇳 · Ting-Ting Sun🇨🇳

    By combining RMF models and equivparticle models with density-dependent quark masses, we construct explicitly ``a quark Fermi Sea'' and ``a baryonic Fermi surface'' to model the quarkyonic phase, where baryons with momentums ranging from zero to Fermi momentums are included. The properties of nuclear matter, quark matter, and quarkyonic matter are then investigated in a unified manner, where quarkyonic matter is more stable and energy minimization is still applicable to obtain the microscopic properties of dense matter. Three different covariant density functionals TW99, PKDD, and DD-ME2 are adopted in our work, where TW99 gives satisfactory predictions for the properties of nuclear matter both in neutron stars and heavy-ion collisions and quarkyonic transition is unfavorable. Nevertheless, if PKDD with larger slope of symmetry energy $L$ or DD-ME2 with larger skewness coefficient $J$ are adopted, the corresponding EOSs are too stiff according to both experimental and astrophysical constraints. The situation is improved if quarkyonic transition takes place, where the EOSs become softer and can accommodate various experimental and astrophysical constraints.

    hep-phnucl-thPRD(2023)·17 citations
12. 12*

    Lepton-pair scattering with an off-shell and an on-shell photon at two loops in massless QED

    Simon Badger🇮🇹 · Jakub Kryś🇮🇹 · Ryan Moodie🇮🇹 · Simone Zoia🇮🇹

    We compute the two-loop QED helicity amplitudes for the scattering of a lepton pair with an off-shell and an on-shell photon, $0\to \ell \bar{\ell }\gamma {\gamma }^{\ast }$, using the approximation of massless leptons. We express all master integrals relevant for the scattering of four massless particles with a single external off-shell leg up to two loops in a basis of algebraically independent multiple polylogarithms, which guarantees an efficient numerical evaluation and compact analytic representations of the amplitudes. Analytic forms of the amplitudes are reconstructed from numerical evaluations over finite fields. Our results complete the amplitude-level ingredients contributing to the N${}^3$LO predictions of electron-muon scattering $e\mu \to e\mu$, which are required to meet the precision goal of the future MUonE experiment.

    hep-phhep-thJHEP(2023)·38 citations
13. 13*

    Constraining Postinflationary Axions with Pulsar Timing Arrays

    Géraldine Servant🇩🇪 · Peera Simakachorn🇪🇸

    Models that produce Axion-Like-Particles (ALP) after cosmological inflation due to spontaneous $U(1)$ symmetry breaking also produce cosmic string networks. Those axionic strings lose energy through gravitational wave emission during the whole cosmological history, generating a stochastic background of gravitational waves that spans many decades in frequency. We can therefore constrain the axion decay constant and axion mass from limits on the gravitational wave spectrum and compatibility with dark matter abundance as well as dark radiation. We derive such limits from analyzing the most recent NANOGrav data from Pulsar Timing Arrays (PTA). The limits are similar to the $N_{\mathrm{eff}}$ bounds on dark radiation for ALP masses $m_a\lesssim 10^{-22}$ eV. On the other hand, for heavy ALPs with $m_a\gtrsim 0.1$ GeV and $N_{\mathrm{DW}}\ne 1$, new regions of parameter space can be probed by PTA data due to the dominant Domain-Wall contribution to the gravitational wave background.

    hep-phastro-ph.COPRD(2023)·65 citations
14. 14*

    Supernova Limits on Muonic Dark Forces

    Claudio Andrea Manzari🇺🇸 · Jorge Martin Camalich🇪🇸 · Jonas Spinner🇩🇪 · Robert Ziegler🇩🇪

    Proto-neutron stars formed during core-collapse supernovae are hot and dense environments that contain a sizable population of muons. If these interact with new long-lived particles with masses up to roughly 100 MeV, the latter can be produced and escape from the stellar plasma, causing an excessive energy loss constrained by observations of SN 1987A. In this article we calculate the emission of light dark fermions that are coupled to leptons via a new massive vector boson, and determine the resulting constraints on the general parameter space. We apply these limits to the gauged $L_{\mu }-L_{\tau }$ model with dark fermions, and show that the SN 1987A constraints exclude a significant portion of the parameter space targeted by future experiments. We also extend our analysis to generic effective four-fermion operators that couple dark fermions to muons, electrons, or neutrinos. We find that SN 1987A cooling probes a new-physics scale up to $\sim 7$ TeV, which is an order of magnitude larger than current bounds from laboratory experiments.

    hep-phastro-ph.HEPRD(2023)·38 citations
15. 15*

    Neutrinos, Dark Matter and Higgs Vacua in Parity Solutions of the strong CP problem

    Michele Redi🇮🇹 · Andrea Tesi🇮🇹

    The strong CP problem can be solved if the laws of nature are invariant under a space-time parity exchanging the Standard Model with its mirror copy. We review and extend different realizations of this idea with the aim of discussing Dark Matter, neutrino physics, leptogenesis and collider physics within the same context. In the minimal realization of Ref. [1] the mirror world contains a massless dark photon, which leads to a rather interesting cosmology. Mirror electrons reproduce the dark matter abundance for masses between 500-1000 GeV with traces of strongly interacting dark matter. This scenario also predicts deviations from cold dark matter, sizable $\Delta N_{\mathrm{eff}}$ and colored states in the TeV range that will be tested in a variety of upcoming experiments. We also explore scenarios where the mirror photon is massive and the mirror particles are charged under ordinary electro-magnetism with very different phenomenology. We also show that, for the measured values of the SM parameters, the Higgs effective potential can give rise to a second minimum at large field value as required to break spontaneously the parity symmetry.

    hep-phastro-ph.COJHEP(2023)·6 citations
16. 16*

    Probing the high temperature symmetry breaking with gravitational waves from domain walls

    Xiu-Fei Li🇨🇳

    The symmetry can be broken at high temperature and then restored at low temperature, which is the so-called \emph{high temperature symmetry breaking}. It often appears in some theories such as the high scale electroweak baryogenesis mechanism. In this paper, we probe the high temperature ${\mathbb{Z}}_2$ symmetry breaking with gravitational waves (GWs) from domain wall annihilation. We first introduce a scalar with ${\mathbb{Z}}_2$ symmetry and few of singlet fermions that interact with scalar through a five-dimension operator. This can lead to the scalar potential has a non-zero minimum at high temperature. At the early stage, the scalar is pinned at symmetric phase due to the large Hubble fraction. When the scalar thermal mass becomes comparable to the Hubble parameter, it can quickly roll down to the minimum of potential. Then the ${\mathbb{Z}}_2$ symmetry is spontaneously broken and the domain walls will form. With the decrease of temperature, ${\mathbb{Z}}_2$ symmetry will be restored. We find that if domain walls are formed at $\mathcal{O}(10^9)\mathrm{GeV}$, the GW produced by domain wall annihilation is expected to be observed by BBO, CE and ET. In addition, we also discuss the relationships between this scenario and NANOGrav signal.

    hep-phastro-ph.CONPB(2025)·40 citations
17. 17*

    The split majoron model confronts the NANOGrav signal and cosmological tensions

    Pasquale Di Bari🇬🇧 · Moinul Hossain Rahat🇬🇧

    In the light of the evidence of a gravitational wave background from the NANOGrav 15yr data set, we reconsider the split majoron model as a new physics extension of the standard model able to generate a needed contribution to solve the current tension between the data and the standard interpretation in terms of inspiraling supermassive black hole massive binaries. In the split majoron model the seesaw right-handed neutrinos acquire Majorana masses from spontaneous symmetry breaking of global $U(1{)}_{B-L}$ in a strong first order phase transition of a complex scalar field occurring above the electroweak scale. The final vacuum expectation value couples to a second complex scalar field undergoing a low scale phase transition occurring after neutrino decoupling. Such a coupling enhances the strength of this second low scale first order phase transition and can generate a sizeable primordial gravitational wave background contributing to the NANOGrav 15yr signal. Some amount of extra-radiation is generated after neutron-to-proton ration freeze-out but prior to nucleosynthesis. This can be either made compatible with current upper bound from primordial deuterium measurements or even be used to solve a potential deuterium problem. Moreover, the free streaming length of light neutrinos can be suppressed by their interactions with the resulting majoron background and this mildly ameliorates existing cosmological tensions. Thus cosmological observations nicely provide independent motivations for the model.

    hep-phastro-ph.COastro-ph.HEhep-thPRD(2024)·56 citations
18. 18*

    Fermion Geometry and the Renormalization of the Standard Model Effective Field Theory

    Benoît Assi🇺🇸 · Andreas Helset🇺🇸 · Aneesh V. Manohar🇺🇸 · Julie Pagès🇺🇸 · Chia-Hsien Shen🇺🇸

    The geometry of field space governs on-shell scattering amplitudes. We formulate a geometric description of effective field theories which extends previous results for scalars and gauge fields to fermions. The field-space geometry reorganizes and simplifies the computation of quantum loop corrections. Using this geometric framework, we calculate the fermion loop contributions to the renormalization group equations for bosonic operators in the Standard Model Effective Field Theory up to mass dimension eight.

    hep-phhep-thJHEP(2023)·49 citations
19. 19*

    Gravitational Waves, Bubble Profile, and Baryon Asymmetry in the Complex 2HDM

    Dorival Gonçalves🇺🇸 · Ajay Kaladharan🇺🇸 · Yongcheng Wu🇨🇳

    This study explores the generation of the observed baryon asymmetry of the Universe within the complex Two Higgs Doublet Model (C2HDM) while considering theoretical and current experimental constraints. In our investigation, we analyze critical elements of the Higgs potential to understand the phase transition pattern. Specifically, we examine the formation of the barrier and the uplifting of the true vacuum state, which play crucial roles in facilitating a strong first-order phase transition. Furthermore, we explore the potential gravitational wave signals associated with this phase transition pattern and investigate the parameter space points that can be probed with LISA. Finally, we compare the impact of different approaches to describing the bubble profile on the calculation of the baryon asymmetry. We contrast the typically used kink profile approximation against the explicit solution of the tunneling profile. We find that a non-negligible range of the C2HDM parameter space results in significant discrepancies in the baryon asymmetry estimation between these two approaches. Through an examination of the parameter space, we identify a benchmark point that satisfies the observed baryon asymmetry.

    hep-phPRD(2023)·41 citations
20. 20*

    Decomposing the Origin of TeV-PeV Emission from the Galactic Plane: Implications of Multi-messenger Observations

    Ke Fang🇺🇸 · Kohta Murase🇺🇸

    High-energy neutrino and $\gamma$-ray emission has been observed from the Galactic plane, which may come from individual sources and/or diffuse cosmic rays. We evaluate the contribution of these two components through the multimessenger connection between neutrinos and $\gamma$ rays in hadronic interactions. We derive maximum fluxes of neutrino emission from the Galactic plane using $\gamma$-ray catalogs, including 4FGL, HGPS, 3HWC, and 1LHAASO, and measurements of the Galactic diffuse emission by Tibet AS$\gamma$ and LHAASO. We find that the IceCube Galactic neutrino flux is larger than the contribution from all resolved sources when excluding promising leptonic sources such as pulsars, pulsar wind nebulae, and TeV halos. Our result indicates that the Galactic neutrino emission is likely dominated by the diffuse emission by the cosmic-ray sea and unresolved hadronic $\gamma$-ray sources. In addition, the IceCube flux is comparable to the sum of the flux of non-pulsar sources and the LHAASO diffuse emission especially above 30 TeV. This implies that the LHAASO diffuse emission may dominantly originate from hadronic interactions, either as the truly diffuse emission or unresolved hadronic emitters. Future observations of neutrino telescopes and air-shower $\gamma$-ray experiments in the Southern hemisphere are needed to accurately disentangle the source and diffuse emission of the Milky Way.

    ↳ astro-ph.HEastro-ph.GAhep-phApJ(2023)·35 citations
21. 21*

    Palatini $F(R,X)$: a new framework for inflationary attractors

    Christian Dioguardi🇪🇪 · Antonio Racioppi🇪🇪

    Palatini $F(R)$ gravity proved to be a powerful tool in order to realize asymptotically flat inflaton potentials. Unfortunately, it also inevitably implies higher-order inflaton kinetic terms in the Einstein frame that might jeopardize the evolution of the system out of the slow-roll regime. We prove that a $F(R+X)$ gravity, where $X$ is the inflaton kinetic term, solves the issue. Moreover, when $F$ is a quadratic function such a choice easily leads to a new class of inflationary attractors, fractional attractors, that generalizes the already well-known polynomial $\alpha$-attractors.

    ↳ gr-qcastro-ph.COhep-phPhys.Dark Univ.(2024)·25 citations
22. 22*

    Collective flow and the fluid behavior in p/d/${}^3$He+Au collisions at $\sqrt{s_{NN}}=200$ GeV

    Zeming Wu🇨🇳 · Baochi Fu🇨🇳 · Shujun Zhao🇨🇳 · Runsheng Liu🇨🇳 · Huichao Song🇨🇳

    By varying the intrinsic initial geometry, the p/d/${}^3$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) provide a unique opportunity to understand the collective behavior and probe the possible sub-nucleon fluctuations in small systems. In this paper, we employ the hybrid model iEBE-VISHNU with Trento initial conditions to study the collective flow and the fluid behavior in p/d/${}^3$He+Au collisions. With fine-tuned parameters, iEBE-VISHNU can describe the $v_2(p_T)$ and $v_3(p_T)$ data from the PHENIX and STAR collaborations. However, for some certain parameter sets with initial sub-nucleon fluctuation, the hydrodynamic simulations have already beyond their limits with the average Knudsen number $⟨K_n⟩$ obviously larger than one. Our calculations demonstrate that, for a meaningful evaluation of the fluid behavior in the small systems, model simulations should also pay attention to the validity range of hydrodynamics.

    ↳ nucl-thhep-phnucl-exCPC(2024)·6 citations
23. 23*

    CFT Correlators and CP-Violating Trace Anomalies

    Claudio Corianò🇮🇹 · Stefano Lionetti🇮🇹 · Matteo Maria Maglio🇩🇪

    We analyze the parity-odd correlators $⟨JJO{⟩}_{odd}$, $⟨JJT{⟩}_{odd}$, $⟨TTO{⟩}_{odd}$ and $⟨TTT{⟩}_{odd}$ in momentum space, constrained by conformal Ward identities, extending our former investigation of the parity-odd chiral anomaly vertex. We investigate how the presence of parity-odd trace anomalies affect such correlators. Motivations for this study come from holography, early universe cosmology and from a recent debate on the chiral trace anomaly of a Weyl fermion. In the current CFT analysis, $O$ can be either a scalar or a pseudoscalar operator and it can be identified with the trace of the stress energy tensor. We find that the $⟨JJO{⟩}_{odd}$ and $⟨TTO{⟩}_{odd}$ can be different from zero in a CFT. This occurs when the conformal dimension of the scalar operator is ${\Delta }_3=4$, as in the case of $O=T_{\mu }^{\mu }$. Moreover, if we assume the existence of parity-odd trace anomalies, the conformal $⟨JJT{⟩}_{odd}$ and $⟨TTT{⟩}_{odd}$ are nonzero. In particular, in the case of $⟨JJT{⟩}_{odd}$ the transverse-traceless component is constrained to vanish, and the correlator is determined only by the trace part with the anomaly pole.

    ↳ hep-thhep-phEPJC(2023)·23 citations
24. 24*

    Superfluid dark matter flow around cosmic strings

    Heliudson Bernardo🇨🇦 · Robert Brandenberger🇨🇦 · Aline Favero🇨🇦

    We consider a cosmic string moving through a gas of superfluid dark matter (SFDM) particles and analyze how it affects the dark matter distribution. We look at two different cases: first, a cosmic string passing through an already condensed region, and second, through a region that is not yet condensed. In the former, the string induces a weak shock in the superfluid, and the Bose-Einstein condensate (BEC) survives. In the latter, a wake of larger density is formed behind the string, and we study under which conditions a BEC can be formed in the virialized region of the wake. By requiring the thermalization of the DM particles and the overlap of their de Broglie wavelengths inside the wake, we obtain an upper bound on the mass of the dark matter particles on the order of 10 eV, which is compatible with typical SFDM models.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2024)·6 citations
25. 25*

    Can baryon asymmetry be explained by a large initial value before inflation?

    Kai Murai🇯🇵 · Fuminobu Takahashi🇯🇵 · Masaki Yamada🇯🇵 · Wen Yin🇯🇵

    We show that the baryon asymmetry of the Universe cannot be explained by a large initial value before inflation because it inevitably predicts correlated baryon isocurvature perturbations that are already excluded by cosmic microwave background observations. Similar arguments can generally be applied to some models of dark matter.

    ↳ astro-ph.COhep-phPRD(2023)·6 citations
26. 26*

    Primordial black holes from a curvaton scenario with strongly non-Gaussian perturbations

    Andrew D. Gow🇬🇧 · Tays Miranda🇫🇮 · Sami Nurmi🇫🇮

    We investigate the production of primordial black holes (PBHs) in a mixed inflaton-curvaton scenario with a quadratic curvaton potential, assuming the curvaton is in de Sitter equilibrium during inflation with $⟨\chi ⟩=0$. In this setup, the curvature perturbation sourced by the curvaton is strongly non-Gaussian, containing no leading Gaussian term. We show that for $m^2/H^2\gtrsim 0.3$, the curvaton contribution to the spectrum of primordial perturbations on CMB scales can be kept negligible but on small scales the curvaton can source PBHs. In particular, PBHs in the asteroid mass range $10^{-16}{M}_{\odot }\lesssim M\lesssim 10^{-10}{M}_{\odot }$ with an abundance reaching $f_{\mathrm{PBH}}=1$ can be produced when the inflationary Hubble scale $H\gtrsim 10^{12}$ GeV and the curvaton decay occurs in the window from slightly before the electroweak transition to around the QCD transition.

    ↳ astro-ph.COgr-qchep-phJCAP(2023)·32 citations
27. 27*

    NANOGrav meets Hot New Early Dark Energy and the origin of neutrino mass

    Juan S. Cruz🇩🇰 · Florian Niedermann🇸🇪 · Martin S. Sloth🇩🇰

    It has recently been speculated that the NANOGrav observations point towards a first-order phase transition in the dark sector at the GeV scale [1]. Here, we show that such a phase transition might already have been predicted in the Hot New Early Dark Energy model (Hot NEDE) [2],[3]. There, it was argued that two dark sector phase transitions are the signature of neutrino mass generation through the inverse seesaw mechanism. In particular, an IR phase transition serves a double purpose by resolving the Hubble tension through an energy injection and generating the Majorana mass entry in the inverse seesaw mixing matrix. This usual NEDE phase transition is then accompanied by a UV counterpart, which generates the heavy Dirac mass entry in the inverse seesaw mass matrix of a right-handed neutrino. Here, we investigate if the UV phase transition of the Hot NEDE model can occur at the GeV scale in view of the recent NANOGrav observations.

    ↳ astro-ph.COhep-phhep-thPLB(2023)·25 citations
28. 28*

    Cosmological Interpretation for the Stochastic Signal in Pulsar Timing Arrays

    Yu-Mei Wu🇨🇳 · Zu-Cheng Chen🇨🇳 · Qing-Guo Huang🇨🇳

    The pulsar timing array (PTA) collaborations have recently reported compelling evidence for the presence of a stochastic signal consistent with a gravitational-wave background. In this letter, we combine the latest data sets from NANOGrav, PPTA and EPTA collaborations to explore the cosmological interpretations for the detected signal from first-order phase transitions, domain walls and cosmic strings, separately. We find that the first-order phase transitions and cosmic strings can give comparable interpretations compared to supermassive black hole binaries (SMBHBs) characterized by a power-law spectrum, but the domain wall model is strongly disfavored with the Bayes factor compared to the SMBHB model being 0.009. Furthermore, the constraints on the parameter spaces indicate that: 1) a strong phase transition at temperatures below the electroweak scale is favored and the bubble collisions make the dominant contribution to the energy density spectrum; 2) the cosmic string tension is $G\mu \in [1.46,15.3]\times 10^{-12}$ at $90\%$ confidence interval and a small reconnection probability $p<6.68\times 10^{-2}$ is preferred at $95\%$ confidence level, implying that the strings in (super)string theory are strongly favored over the classical field strings.

    ↳ astro-ph.COgr-qchep-phSCPMA(2024)·86 citations
29. 29*

    Where shadows lie: reconstruction of anisotropies in the neutrino sky

    Willem Elbers🇬🇧 · Carlos S. Frenk🇬🇧 · Adrian Jenkins🇬🇧 · Baojiu Li🇬🇧 · Silvia Pascoli🇮🇹 · Jens Jasche🇸🇪 · Guilhem Lavaux🇫🇷 · Volker Springel🇩🇪

    The Cosmic Neutrino Background (CNB) encodes a wealth of information, but has not yet been observed directly. To determine the prospects of detection and to study its information content, we reconstruct the phase-space distribution of local relic neutrinos from the three-dimensional distribution of matter within 200 Mpc/h of the Milky Way. Our analysis relies on constrained realization simulations and forward modelling of the 2M++ galaxy catalogue. We find that the angular distribution of neutrinos is anti-correlated with the projected matter density, due to the capture and deflection of neutrinos by massive structures along the line of sight. Of relevance to tritium capture experiments, we find that the gravitational clustering effect of the large-scale structure on the local number density of neutrinos is more important than that of the Milky Way for neutrino masses less than 0.1 eV. Nevertheless, we predict that the density of relic neutrinos is close to the cosmic average, with a suppression or enhancement over the mean of (-0.3%, +7%, +27%) for masses of (0.01, 0.05, 0.1) eV. This implies no more than a marginal increase in the event rate for tritium capture experiments like PTOLEMY. We also predict that the CNB and CMB rest frames coincide for 0.01 eV neutrinos, but that neutrino velocities are significantly perturbed for masses larger than 0.05 eV. Regardless of mass, we find that the angle between the neutrino dipole and the ecliptic plane is small, implying a near-maximal annual modulation in the bulk velocity. Along with this paper, we publicly release our simulation data, comprising more than 100 simulations for six different neutrino masses.

    ↳ astro-ph.COhep-phJCAP(2023)·16 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.