Tue·Jun 23, 2020Tuesday·June 23, 2020

1. 01*

   Drell-Yan $q_T$ Resummation of Fiducial Power Corrections at N${}^3$LL

   Markus A. Ebert🇺🇸 · Johannes K. L. Michel🇩🇪 · Iain W. Stewart🇺🇸 · Frank J. Tackmann🇩🇪

   We consider Drell-Yan production $pp\to V^{\ast }X\to LX$ at small $q_T\ll Q$. Experimental measurements require fiducial cuts on the leptonic state $L$, which introduce enhanced, linear power corrections in $q_T/Q$. We show that they can be unambiguously predicted from factorization, and resummed to the same order as the leading-power contribution. We thus obtain predictions for the fiducial $q_T$ spectrum to N3LL and next-to-leading-power in $q_T/Q$. Matching to full NNLO (${\alpha }_s^2$), we find that the linear power corrections are indeed the dominant ones, and the remaining fixed-order corrections become almost negligible below $q_T\lesssim 40$ GeV. We also discuss the implications for more complicated observables, and provide predictions for the fiducial ${\varphi }^{\ast }$ spectrum at N3LL+NNLO. We find excellent agreement with ATLAS and CMS measurements of $q_T$ and ${\varphi }^{\ast }$. We also consider the $p_T^{\ell }$ spectrum. We show that it develops leptonic power corrections in $q_T/(Q-2p_T^{\ell })$, which diverge near the Jacobian peak $p_T^{\ell }\sim Q/2$ and must be kept to all powers to obtain a meaningful result there. Doing so, we obtain for the first time an analytically resummed result for the $p_T^{\ell }$ spectrum around the Jacobian peak at N3LL+NNLO. Our method is based on performing a complete tensor decomposition for hadronic and leptonic tensors. In practice this is equivalent to often-used recoil prescriptions, for which our results now provide rigorous, formal justification. Our tensor decomposition yields nine Lorentz-scalar hadronic structure functions, which directly map onto the commonly used angular coefficients, but also holds for arbitrary leptonic final states. In particular, for suitably defined Born-projected leptons it still yields a LO-like angular decomposition even when including QED final-state radiation. We also discuss the application to $q_T$ subtractions.

   hep-phhep-exnucl-thJHEP(2021)·146 citations
2. 02*

   $\mu \to e\gamma$ selecting scalar leptoquark solutions for the $(g-2{)}_{e,\mu }$ puzzles

   Ilja Doršner🇭🇷 · Svjetlana Fajfer🇸🇮 · Shaikh Saad🇺🇸

   We investigate all potentially viable scenarios that can produce the chiral enhancement required to simultaneously explain the $(g-2{)}_e$ and $(g-2{)}_{\mu }$ data with either a single scalar leptoquark or a pair of scalar leptoquarks. We provide classification of these scenarios in terms of their ability to satisfy the existing limits on the branching ratio for the $\mu \to e\gamma$ process. The simultaneous explanation of the $(g-2{)}_{e,\mu }$ discrepancies, coupled with the current experimental data, implies that the $(g-2{)}_e$ loops are exclusively due to the charm quark propagation whereas the $(g-2{)}_{\mu }$ loops are due to the top quark propagation. The scenarios where the $(g-2{)}_e$ loops are due to the top (bottom) quark propagation are, at best, approximately nine (three) orders of magnitude away from the experimental limit on the $\mu \to e\gamma$ branching ratio. All in all, there are only three particular scenarios that can pass the $\mu \to e\gamma$ test and simultaneously create large enough impact on the $(g-2{)}_{e,\mu }$ discrepancies when the new physics is based on the Standard Model fermion content. These are the $S_1$, $R_2$, and $S_1\&S_3$ scenarios, where the first two are already known to be phenomenologically viable candidates with respect to all other flavor and collider data constraints. We show that the third scenario, where the right-chiral couplings to charged leptons are due to $S_1$, the left-chiral couplings to charged leptons are due to $S_3$, and the two leptoquarks mix through the Standard Model Higgs field, cannot address the $(g-2{)}_e$ and $(g-2{)}_{\mu }$ discrepancies at the $1\sigma$ level due to an interplay between $K_L^0\to e^{\pm }{\mu }^{\mp }$, $Z\to e^{+}{e}^{-}$, and $Z\to {\mu }^{+}{\mu }^{-}$ data despite the ability of that scenario to avoid the $\mu \to e\gamma$ limit.

   hep-phPRD(2020)·88 citations
3. 03*

   High energy QCD: multiplicity distribution and entanglement entropy

   E. Gotsman (Tel Aviv U.)🇮🇱 · E. Levin (Tel Aviv U./UTFSM)🇮🇱

   In this paper we show that QCD at high energies leads to the multiplicity distribution $\frac{{\sigma }_n}{{\sigma }_{\mathrm{in}}}=\frac{1}{N}\text{Lb}\frac{N-1}{N}{\text{Rb}}^{n-1}$, (where $N$ denotes the average number of particles), and to entanglement entropy $S=\ln N$, confirming that the partonic stat at high energy is maximally entangled. However, the value of $N$ depends on the kinematics of the parton cascade. In particular, for DIS$N=xG(x,Q)$ , where $xG$ is the gluon structure function, whil for hadron-hadron collisions, $N\propto Q_S^2(Y)$, where $Q_s$ denotes the saturation scale. We checked that this multiplicity distribution describes the LHC data for low multiplicities $n<(3÷5)N$, exceeding it for larger values of $n$. We view this as a result of our assumption, that the system of partons in hadron-hadron collisions atc.m. rapidity $Y=0$ is dilute. We show that the data can be described at large multiplicities in the parton model, if we do not make this assumption.

   hep-phPRD(2020)·43 citations
4. 04*

   Atmospheric Dark Matter and Xenon1T Excess

   Liangliang Su🇨🇳 · Wenyu Wang🇨🇳 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳 · Bin Zhu🇨🇳

   Very recently, the Xenon1T collaboration has reported an intriguing electron recoil excess, which may imply for light dark matter. In order to interpret this anomaly, we propose the atmospheric dark matter (ADM) from the inelastic collision of cosmic rays (CRs) with the atmosphere. Due to the boost effect of high energy CRs, we show that the light ADM can be fast-moving and successfully fit the observed electron recoil spectrum through the ADM-electron scattering process. Meanwhile, our ADM predicts the scattering cross section ${\sigma }_e\sim \mathcal{O}(10^{-38}-10^{-39}$) cm${}^2$, and thus can evade other direct detection constraints. The search for light meson rare decays, such as $\eta \to \pi +\text{slashed}{E}_T$, would provide a complementary probe of our ADM in the future.

   hep-phastro-ph.COPRD(2020)·118 citations
5. 05*

   Prospects of non-resonant di-Higgs searches and Higgs boson self-coupling measurement at the HE-LHC using machine learning techniques

   Amit Adhikary🇮🇳 · Rahool Kumar Barman🇮🇳 · Biplob Bhattacherjee🇮🇳

   The prospects of observing the non-resonant di-Higgs production in the Standard Model at the proposed high energy upgrade of the LHC, $viz.$ the HE-LHC ($\sqrt{s}=27\mathrm{TeV}$ and $\mathcal{L}=15\mathrm{a}{\mathrm{b}}^{-1}$) is studied. Various di-Higgs final states are considered based on their cleanliness and signal yields. The search for the non-resonant double Higgs production at the HE-LHC is performed in the $b\bar{b}\gamma \gamma$, $b\bar{b}{\tau }^{+}{\tau }^{-}$, $b\bar{b}W{W}^{\ast }$, $W{W}^{\ast }\gamma \gamma$, $b\bar{b}Z{Z}^{\ast }$ and $b\bar{b}{\mu }^{+}{\mu }^{-}$ channels. The signal-background discrimination is performed through multivariate analyses using the Boosted Decision Tree Decorrelated (BDTD) algorithm in the TMVA framework, the XGBoost toolkit and Deep Neural Network (DNN). The variation in the kinematics of Higgs pair production as a function of the self-coupling of the Higgs boson, ${\lambda }_h$, is also studied. The ramifications of varying ${\lambda }_h$ on the $b\bar{b}\gamma \gamma$, $b\bar{b}{\tau }^{+}{\tau }^{-}$ and $b\bar{b}W{W}^{\ast }$ search analyses optimized for the SM hypothesis is also explored.

   hep-phhep-exJHEP(2020)·15 citations
6. 06*

   Neutrino self-interactions and XENON1T electron recoil excess

   Andreas Bally🇩🇪 · Sudip Jana🇩🇪 · Andreas Trautner🇩🇪

   The XENON1T collaboration recently reported an excess in electron recoil events in the energy range between $1-7\mathrm{keV}$. This excess could be understood to originate from the known solar neutrino flux, if neutrinos couple to a light vector-mediator with strength $g_{\nu N}$ that kinetically mixes with the photon with strength $\chi$, and $g_{\nu N}\chi \sim 10^{-13}$. Here, we show that such coupling values can naturally arise in a renormalizable model of long-range vector-mediated neutrino self-interactions. The model could be discriminated from other explanations of the XENON1T excess by the characteristic $1/T^2$ energy dependence of the neutrino-electron scattering cross section. Other signatures include invisible Higgs and $Z$ decays and lepto-philic charged Higgses at a few $100\mathrm{GeV}$. ALPS II will probe part of the viable parameter space.

   hep-phhep-exPRL(2020)·92 citations
7. 07*

   Inelastic Dark Matter Electron Scattering and the XENON1T Excess

   Keisuke Harigaya🇺🇸 · Yuichiro Nakai🇨🇳 · Motoo Suzuki🇨🇳

   Detection of electron recoils by dark matter (DM) may reveal the structure of the dark sector. We consider a scenario where a heavier DM particle inelastically scatters off an electron and is converted into a lighter DM particle. A small mass difference between the two DM particles is transferred into electron recoil energy. We investigate the DM-electron interaction mediated by a massive dark photon and evaluate the inelastic DM scattering rate, taking account of the atomic structure. It is found that the scattering rate is significantly enhanced because of the small mass splitting, which allows for a small momentum transfer matched with the size of the electron wave function. We show that there exists a viable parameter space which explains the excess of electron recoil events around 2-3 keV recently reported by the XENON1T experiment.

   hep-phastro-ph.COhep-exPLB(2020)·91 citations
8. 08*

   Assessing the accuracy of the GENIE event generator with electron-scattering data

   Artur M. Ankowski🇺🇸 · Alexander Friedland🇺🇸

   Precision neutrino oscillation experiments of the future---of which DUNE is a prime example---require reliable event generator tools. The 1--4 GeV energy regime, in which DUNE will operate, is marked by the transition from the low-energy nuclear physics domain to that of perturbative QCD, resulting in rich and highly complex physics. Given this complexity, it is important to establish a validation procedure capable of disentangling the physical processes and testing each of them individually. Here, we demonstrate the utility of this approach by benchmarking the GENIE generator, currently used by all Fermilab-based experiments, against a broad set of inclusive electron-scattering data. This comparison takes advantage of the fact that, while electron-nucleus and neutrino-nucleus processes share a lot of common physics, electron scattering gives one access to precisely known beam energies and scattering kinematics. Exploring the kinematic parameter range relevant to DUNE in this manner, we observe patterns of large discrepancies between the generator and data. These discrepancies are most prominent in the pion-producing regimes and are present not only in medium-sized nuclei, including argon, but also in deuterium and hydrogen targets, indicating mismodeled hadronic physics. Several directions for possible improvement are discussed.

   hep-phhep-exnucl-exnucl-thPRD(2020)·32 citations
9. 09*

   On-shell mediator dark matter models and the Xenon1T anomaly

   Mingxuan Du🇨🇳 · Jinhan Liang🇨🇳 · Zuowei Liu🇨🇳 · Van Que Tran🇨🇳 · Yilun Xue🇨🇳

   We present a dark matter model to explain the excess events in the electron recoil data recently reported by the Xenon1T experiment. In our model, dark matter $\chi$ annihilates into a pair of on-shell particles $\varphi$ which subsequently decay into $\psi \psi$ final state; $\psi$ interacts with electron to generate the observed excess events. Due to the mass hierarchy, the velocity of $\psi$ can be rather large and can have an extended distribution, which provides a good fit to the electron recoil energy spectrum. We estimated the flux of $\psi$ from dark matter annihilations in the galaxy and further determined the interaction cross section which is sizable but small enough to allow $\psi$ to penetrate the rocks to reach the underground labs.

   hep-phCPC(2021)·58 citations
10. 10*

    Fully-heavy tetraquark states and their evidences in the LHC observations

    Ming-Sheng liu🇨🇳 · Feng-Xiao Liu🇨🇳 · Xian-Hui Zhong🇨🇳 · Qiang Zhao🇨🇳

    Stimulated by the exciting progress on the observations of the fully-charmed tetraquarks at LHC, we carry out a combined analysis of the mass spectra and fall-apart decays of the $1S$-, $2S$-, and $1P$-wave $cc\bar{c}\bar{c}$ states in a nonrelativistic quark model (NRQM). It is found that the $X(6600)$ structure observed in the di-$J/\psi$ invariant mass spectrum can be explained by the $1S$-wave state $T_{(4c)0^{++}}(6550)$. This structure may also bear some feed-down effects from the higher $2S$ and/or $1P$ tetraquark states. The $X(6900)$ structure observed in both the di-$J/\psi$ and $J/\psi \psi (2S)$ channels can be naturally explained by the $2S$-wave state $T_{(4c)0^{++}}(6957)$. The small shoulder structure around $6.2-6.4$ GeV observed at CMS and ATLAS may be due to the feed-down effects from some $1P$-wave states with $C=-1$ and/or some $2S$-wave states with $J^{PC}=0^{++}$. Other decay channels are implied in such a scenario and they can be investigated by future experimental analyses. Considering the large discovery potential at LHC, we also present predictions for the $bb\bar{b}\bar{b}$ states which can be searched for in the future.

    hep-phhep-exPRD(2024)·135 citations
11. 11*

    New Hybrid Textures for Neutrino Mass Matrices

    S. Dev🇮🇳 · Desh Raj🇮🇳

    We perform a systematic investigation of the texture structures of Majorana neutrino mass matrix $M_{\nu }$ having two texture zeros and an equality between two nonzero matrix elements, in the light of recent neutrino oscillation data. Among forty-two possible textures, it is found that only eight textures are compatible with the current experimental data at 3$\sigma$ C.L. Out of these phenomenologically viable textures, six follow normal mass ordering while remaining two satisfy the inverted mass ordering of neutrino mass spectrum. In the numerical analysis, we carry out a scan over the possible space of all viable patterns. We present the implications of each allowed patterns for three mixing angles (solar, reactor and atmospheric), leptonic CP-violation, neutrino mass scale and the neutrinoless double beta decay indicating strong correlations between oscillation parameters. The symmetry realization of one of the viable textures is also presented.

    hep-phNPB(2020)·14 citations
12. 12*

    Excess of soft dielectrons and photons

    I.M. Dremin🇷🇺

    Spectra of unbound electron-positron pairs (dielectrons, in brief) and photons from decays of parapositronia produced in ultraperipheral collisions of electrically charged objects are calculated. Their shapes at energies of the NICA collider are demonstrated. Soft dielectrons and photons are abundantly produced. The relevance of these processes to the astrophysical problem of cooling electron-positron pairs and the intense emission of 511 keV photons from the Galactic center is discussed.

    hep-phastro-ph.HEhep-exnucl-ex+1Universe(2020)·7 citations
13. 13*

    Charged-Current Muonic Reactions in Core-Collapse Supernovae

    Gang Guo🇩🇪 · Gabriel Martínez-Pinedo🇩🇪 · Andreas Lohs🇩🇪 · Tobias Fischer🇵🇱

    The steady advance in core-collapse supernova simulations requires a more precise description of neutrino processes in hot and dense matter. In this work, we study the rates of charged-current (CC) weak processes with (anti)muons in supernova matter. At the relativistic mean field level, we derive results for the rates of CC neutrino-nucleon reactions, taking into account full kinematics, weak magnetism and pseudoscalar terms, and $q^2$-dependent nucleon form factors in the hadronic current. In addition to muonic semileptonic processes we also consider purely leptonic processes. In particular, we show that inverse muon decay can dominate the opacities for low energy ${\nu }_{\mu }$ and ${\bar{\nu }}_e$ at densities $\gtrsim 10^{13}\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$.

    hep-phastro-ph.HEPRD(2020)·59 citations
14. 14*

    Exploring the double-slit interference with linearly polarized photons

    Wangmei Zha🇨🇳 · James Daniel Brandenburg🇨🇳 · Lijuan Ruan🇺🇸 · Zebo Tang🇨🇳 · Zhangbu Xu🇺🇸

    The linearly polarized quasi-real photons from the highly Lorentz-contracted Coulomb fields of relativistic heavy ions can fluctuate to quark-antiquark pairs, scatter off a target nucleus and emerge as vector mesons. In the process, the two colliding nuclei can switch roles to act as photon emitter or target, forming a double-slit interference pattern. The product from photoproduction inherits the photon polarization states, leading to the asymmetries of the decay angular distributions. In this letter, we study the interference effect in polarization dimension from the asymmetries of the decay angular distributions for photoprodution in heavy-ion collisions and find a periodic oscillation with the transverse momentum of vector meson, which could reasonably explain the transverse momentum dependence of the 2nd-order modulation in azimuth for the ${\rho }^0$ decay observed by the STAR collaboration.

    hep-phPRD(2021)·46 citations
15. 15*

    The impact of nonminimal Universal Extra Dimensional model on $\Delta B=2$ transitions

    Avirup Shaw🇮🇳

    We measure the impact of nonvanishing boundary localised terms on $\Delta B=2$ transitions in five-dimensional Universal Extra Dimensional scenario where masses and coupling strengths of several interactions of Kaluza-Klein modes are significantly modified with respect to the minimal counterpart. In such scenario we estimate the Kaluza-Klein contributions of quarks, gauge bosons and charged Higgs by evaluating the one-loop box diagrams that are responsible for the $\Delta B=2$ transitions. Using the loop function (obtained from one-loop box diagrams) we determine several important elements that are involved in Wolfenstein parametrisation. Moreover, with these elements we also study the geometrical shape of unitarity triangle. Besides, we compute the quantity $\Delta M_s$ scaled by the corresponding Standard Model value. Outcomes of our theoretical predictions have been compared to the allowed ranges of the corresponding observables simultaneously. Our current analysis shows that, depending on the parameters in this scenario the lower limit on the inverse of the radius of compactification can reach to an appreciable large value ($\approx 1.48$ TeV or even higher).

    hep-phEPJC(2021)·2 citations
16. 16*

    The Higgs Potential in 2HDM extended with a Real Triplet Scalar: A roadmap

    B. Ait-Ouazghour🇲🇦 · M. Chabab🇲🇦

    We perform a comprehensive study of The Higgs potential of the two Higgs doublet model extended by a real triplet scalar field $\Delta$. This model, dubbed $2\mathcal{H}\mathcal{D}\mathcal{M}+\mathcal{T}$, has a rich Higgs spectrum consisting of three CP-even Higgs $h_{1,2,3}$, one CP-odd $A_0$ and two pairs of charged Higgs $H_{1,2}^{\pm }$. First, we determine the perturbative unitarity constraints and a set of non trivial conditions for the boundedness from below (BFB). Then we derive the Veltman conditions by considering the quadratic divergencies of Higgs boson self energies in $2\mathcal{H}\mathcal{D}\mathcal{M}+\mathcal{T}$. We find that the parameter space is severely delimited by these theoretical constraints, as well as experimental exclusion limits and Higgs signal rate measurements at LEP and LHC. Using HiggsBounds-5.3.2beta and HiggSignals-2.2.3beta public codes an exclusion test at $2\sigma$ is then performed on the physical scalars of $2\mathcal{H}\mathcal{D}\mathcal{M}+\mathcal{T}$. Our analysis provides a clear insight on the nonstandard scalar masses, showing that the allowed ranges are strongly sensitive to the sign of mixing angle ${\alpha }_1$, essentially when naturalness is involved. For ${\alpha }_1<0$ scenario, our results place higher limits on the bounds of all scalar masses, and show that the pairs $(h_2,H_1^{\pm })$ and $(h_3,H_2^{\pm })$ are nearly mass degenerate varying within the intervals $[130,246]$~GeV and $[160,335]$~GeV respectively. When ${\alpha }_1$ turns positive, we show that consistency with theoretical constraints and current LHC data, essentially on the diphoton decay channel, favors Higgs masses varying within wide allowed ranges: $[153,973]$~GeV for $m_{A_0}$; $[151,928]$~GeV for ($m_{h_2}$, $m_{H_1^{\pm }}$) and $[186,979]$~GeV for ($m_{h_3}$, $m_{H_2^{\pm }}$). Finally, we find that the $\gamma \gamma$ and $Z\gamma$ Higgs decay modes are generally correlated.

    hep-phInt.J.Mod.Phys.A(2021)·11 citations
17. 17*

    General RGEs for dimensionful couplings in the $\overline{\mathrm{MS}}$ scheme

    Lohan Sartore🇫🇷

    Recently, Poole & Thomsen have presented the Renormalization Group Equations (RGEs) in the $\overline{\mathrm{MS}}$ scheme for dimensionless parameters of a general renormalizable gauge theory in a new formalism based on the Local Renormalization Group. In this Letter, we apply the dummy field method to the expressions in this formalism in order to derive the RGEs for the dimensionful couplings which so far have been missing in this approach. The complete set of RGEs has been implemented in a new version of the public code PyR@TE (arXiv:2007.12700) dedicated to the automatic computation of the RGEs for any general renormalizable (non-supersymmetric) gauge theory.

    hep-phhep-thPRD(2020)·15 citations
18. 18*

    $\theta$-dependence of light nuclei and nucleosynthesis

    Dean Lee🇺🇸 · Ulf-G. Meißner🇩🇪 · Keith A. Olive🇺🇸 · Mikhail Shifman🇺🇸 · Thomas Vonk🇩🇪

    We investigate the impact of the QCD vacuum at nonzero $\theta$ on the properties of light nuclei, Big Bang nucleosynthesis, and stellar nucleosynthesis. Our analysis starts with a calculation of the $\theta$-dependence of the neutron-proton mass difference and neutron decay using chiral perturbation theory. We then discuss the $\theta$-dependence of the nucleon-nucleon interaction using a one-boson-exchange model and compute the properties of the two-nucleon system. Using the universal properties of four-component fermions at large scattering length, we then deduce the binding energies of the three-nucleon and four-nucleon systems. Based on these results, we discuss the implications for primordial abundances of light nuclei, the production of nuclei in stellar environments, and implications for an anthropic view of the universe.

    hep-phastro-ph.COhep-thnucl-thPRResearch(2020)·39 citations
19. 19*

    The role of zero-mode contributions in the matching for the twist-3 PDFs $e(x)$ and $h_L(x)$

    Shohini Bhattacharya🇺🇸 · Krzysztof Cichy🇵🇱 · Martha Constantinou🇺🇸 · Andreas Metz🇺🇸 · Aurora Scapellato🇵🇱 · Fernanda Steffens🇩🇪

    The perturbative procedure of matching was proposed to connect parton quasi-distributions that are calculable in lattice QCD to the corresponding light-cone distributions which enter physical processes. Such a matching procedure has so far been limited to the twist-2 distributions. Recently, we addressed the matching for the twist-3 PDF $g_T(x)$. In this work, we extend our perturbative calculations to the remaining twist-3 PDFs, $e(x)$ and $h_L(x)$. In particular, we discuss the non-trivialities involved in the calculation of the singular zero-mode contributions for the quasi-PDFs.

    hep-phhep-latPRD(2020)·60 citations
20. 20*

    XENON1T Anomaly and its Implication for Decaying Warm Dark Matter

    Gongjun Choi🇨🇳 · Motoo Suzuki🇨🇳 · Tsutomu T. Yanagida🇨🇳

    An excess in the electronic recoil data was observed in the XENON1T detector. One of plausible explanations for the excess is absorption of a vector bosonic particle with the mass of $2-3\mathrm{keV}$. For this, the kinetic mixing $\kappa \sim 10^{-15}$ of the dark photon with the photon is required if the dark photon explains the current DM abundance. We recently proposed a model where the main component DM today is a decaying warm dark matter (WDM) with the life time comparable to the age of the current universe. The WDM decays to a massless fermion and a massive dark photon. This model was originally designed for addressing both the small scale problems which $\Lambda$CDM suffers from and the $H_0$ tension. In this letter, we show that the massive dark photon produced by the WDM decay can be identified with the vector boson inducing the anomalous excess in the XENON1T experiment. Depending on a lifetime of the parent decaying WDM, the dark photon could be either the main component or the sub-component of DM population today.

    hep-phastro-ph.COPLB(2020)·71 citations
21. 21*

    Extraction of Next-to-Next-to-Leading-Order PDFs from Lattice QCD Calculations

    Zheng-Yang Li🇨🇳 · Yan-Qing Ma🇨🇳 · Jian-Wei Qiu🇺🇸

    We present for the first time complete next-to-next-to-leading-order coefficient functions to match flavor non-singlet quark correlation functions in position space, which are calculable in lattice QCD, to parton distribution functions (PDFs). Using PDFs extracted from experimental data and our calculated matching coefficients, we predict valence-quark correlation functions that can be confronted by lattice QCD calculations. The uncertainty of our predictions is greatly reduced with higher order matching coefficients. By performing Fourier transformation, we also obtain matching coefficients for corresponding quasi-PDFs and pseudo-PDFs. Our method of calculations can be readily generalized to evaluate the matching coefficients for sea-quark and gluon correlation functions, putting the program to extract partonic structure of hadrons from lattice QCD calculations to be comparable with and complementary to that from experimental measurements.

    hep-phhep-latPRL(2021)·88 citations
22. 22*

    Stellar Basins of Gravitationally Bound Particles

    Ken Van Tilburg🇺🇸

    A new physical phenomenon is identified: volumetric stellar emission into gravitationally bound orbits of weakly coupled particles such as axions, moduli, hidden photons, and neutrinos. While only a tiny fraction of the instantaneous luminosity of a star (the vast majority of the emission is into relativistic modes), the continual injection of these particles into a small part of phase space causes them to accumulate over astrophysically long time scales, forming what I call a "stellar basin", in analogy with the geologic kind. The energy density of the Solar basin will surpass that of the relativistic Solar flux at Earth's location after only a million years, for any sufficiently long-lived particle produced through an emission process whose matrix elements are unsuppressed at low momentum. This observation has immediate and striking consequences for direct detection experiments---including new limits on axion parameter space independent of dark matter assumptions---and may also increase the prospects for indirect detection of weakly interacting particles around compact stars.

    hep-phastro-ph.HEastro-ph.SRhep-exPRD(2021)·68 citations
23. 23*

    Jet Topology

    Lingfeng Li🇨🇳 · Tao Liu🇨🇳 · Si-Jun Xu🇨🇳

    We introduce persistent Betti numbers to characterize topological structure of jets. These topological invariants measure multiplicity and connectivity of jet branches at a given scale threshold, while their persistence records evolution of each topological feature as this threshold varies. With this knowledge, in particular, we are able to reconstruct branch phylogenetic tree of each jet. These points are demonstrated in the benchmark scenario of light-quark versus gluon jets. This study provides a topological tool to develop jet taggers, and opens a new angle to look into jet physics.

    hep-ph6 citations
24. 24*

    Sun Heated MeV-scale Dark Matter and the XENON1T Electron Recoil Excess

    Yifan Chen (ITP, CAS)🇨🇳 · Ming-Yang Cui (PMO, CAS)🇨🇳 · Jing Shu (ITP, CAS)🇨🇳 · Xiao Xue (ITP, CAS)🇨🇳 · Guanwen Yuan (PMO, CAS)🇨🇳 · Qiang Yuan (PMO, CAS)🇨🇳

    The XENON1T collaboration reported an excess of the low-energy electron recoil events between 1 and 7 keV. We explore the possibility to explain such an anomaly by the MeV-scale dark matter (DM) heated by the interior of the Sun due to the same DM-electron interaction as in the detector. The kinetic energies of heated DM particles can reach a few keV, and can potentially account for the excess signals detected by XENON1T. We study different form factors of the DM-electron interactions, $F(q)\propto q^i$ with $i=0,1,2$ and $q$ being the momentum exchange, and find that for all these cases the inclusion of the Sun-heated DM component improves the fit to the XENON1T data. The inferred DM-electron scattering cross section (at $q=\alpha m_e$ where $\alpha$ is the fine structure constant and $m_e$ is electron mass) is from $\sim 10^{-38}$~cm${}^2$ (for $i=0$) to $\sim 10^{-42}$~cm${}^2$ (for $i=2$). We also derive constraints on the DM-electron cross sections for different form factors, which are stronger than previous results with similar assumptions. We emphasize that the Sun-heated DM scenario relies on the minimum assumption on DM models, which serves as a general explanation of the XENON1T anomaly via DM-electron interaction. The spectrum of the Sun-heated DM is typically soft comparing to other boosted DM, so the small recoil events are expected to be abundant in this scenario. More sensitive direct detection experiments with lower thresholds can possibly distinguish this scenario with other boosted DM models or solar axion models.

    hep-phJHEP(2021)·74 citations
25. 25*

    Light vector mediators facing XENON1T data

    D. Aristizabal Sierra🇨🇱 · V. De Romeri🇪🇸 · L. J. Flores🇲🇽 · D. K. Papoulias🇬🇷

    Recently the XENON1T collaboration has released new results on searches for new physics in low-energy electronic recoils. The data shows an excess over background in the low-energy tail, particularly pronounced at about $2-3$ keV. With an exposure of $0.65$ tonne-year, large detection efficiency and energy resolution, the detector is sensitive as well to solar neutrino backgrounds, with the most prominent contribution given by $pp$ neutrinos. We investigate whether such signal can be explained in terms of new neutrino interactions with leptons mediated by a light vector particle. We find that the excess is consistent with this interpretation for vector masses below $\lesssim 0.1$ MeV. The region of parameter space probed by the XENON1T data is competitive with constraints from laboratory experiments, in particular GEMMA, Borexino and TEXONO. However we point out a severe tension with astrophysical bounds and cosmological observations.

    hep-phPLB(2020)·81 citations
26. 26*

    Explaining the XENON1T excess with Luminous Dark Matter

    Nicole F. Bell🇦🇺 · James B. Dent🇺🇸 · Bhaskar Dutta🇺🇸 · Sumit Ghosh🇺🇸 · Jason Kumar🇺🇸 · Jayden L. Newstead🇦🇺

    We show that the excess in electron recoil events seen by the XENON1T experiment can be explained by relatively low-mass Luminous Dark Matter candidate. The dark matter scatters inelastically in the detector (or the surrounding rock), to produce a heavier dark state with a ~2.75 keV mass splitting. This heavier state then decays within the detector, producing a peak in the electron recoil spectrum which is a good fit to the observed excess. We comment on the ability of future direct detection datasets to differentiate this model from other Beyond the Standard Model scenarios, and from possible tritium backgrounds, including the use of diurnal modulation, multi-channel signals etc.,~as possible distinguishing features of this scenario.

    hep-phastro-ph.COPRL(2020)·82 citations
27. 27*

    Shining dark matter in Xenon1T

    Gil Paz🇺🇸 · Alexey A. Petrov🇺🇸 · Michele Tammaro🇺🇸 · Jure Zupan🇺🇸

    We point out that a non-relativistic $\sim 2$ GeV dark matter (DM) which interacts with visible matter through higher dimensional Rayleigh operators could explain the excess of "electron recoil" events recently observed by the Xenon1T collaboration. A DM scattering event results in a few keV photon that on average carries most of the deposited energy, while the nuclear recoil energy is only a subleading correction. Since the Xenon1T detector does not discriminate between electrons and photons, such events would be interpreted as excess of the keV electrons. Indirect constraints from dark matter annihilation are avoided for light mediators of $\mathcal{O}(10\mathrm{MeV})$ that have sizable couplings to neutrinos. One loop induced spin-independent scattering in dark matter may soon lead to a confirmation signal or already excludes regions of viable parameter space for the Rayleigh DM model, depending on what the exact values of the unknown nonperturbative nuclear matrix elements are.

    hep-phPRD(2021)·56 citations
28. 28*

    Fluctuation-induced higher-derivative couplings and infrared dynamics of the Quark-Meson-Diquark Model

    Niklas Cichutek🇩🇪 · Florian Divotgey🇩🇪 · Jürgen Eser🇩🇪

    In a qualitative study, the low-energy properties of the $\text{SO}\left(6\right)$-symmetric Quark-Meson-Diquark Model as an effective model for two-color Quantum Chromodynamics are investigated within the Functional Renormalization Group (FRG) approach. In particular, we compute the infrared scaling behavior of fluctuation-induced higher-derivative couplings of the linear Quark-Meson-Diquark Model and map the resulting renormalized effective action onto its nonlinear counterpart. The higher-derivative couplings of the nonlinear model, which we identify as the low-energy couplings of the Quark-Meson-Diquark Model, are therefore entirely determined by the FRG flow of their linear equivalents. This grants full access to their scaling behavior and provides insights into conceptual aspects of purely bosonic effective models, as they are treated within the FRG. In this way, the presented work is understood as an immediate extension of our recent advances in the $\text{SO}\left(4\right)$-symmetric Quark-Meson Model beyond common FRG approximations.

    hep-phhep-thnucl-thPRD(2020)·15 citations
29. 29*

    Solar axions cannot explain the XENON1T excess

    Luca Di Luzio🇩🇪 · Marco Fedele🇪🇸 · Maurizio Giannotti🇺🇸 · Federico Mescia🇪🇸 · Enrico Nardi🇮🇹

    We argue that the interpretation in terms of solar axions of the recent XENON1T excess is not tenable when confronted with astrophysical observations of stellar evolution. We discuss the reasons why the emission of a flux of solar axions sufficiently intense to explain the anomalous data would radically alter the distribution of certain type of stars in the color-magnitude diagram in first place, and would also clash with a certain number of other astrophysical observables. Quantitatively, the significance of the discrepancy ranges from $3.3\sigma$ for the rate of period change of pulsating White Dwarfs, and exceedes $19\sigma$ for the $R$-parameter and for $M_{I,\mathrm{TRGB}}$.

    hep-phastro-ph.GAastro-ph.SRhep-exPRL(2020)·116 citations
30. 30*

    Galactic Origin of Relativistic Bosons and XENON1T Excess

    Jatan Buch🇺🇸 · Manuel A. Buen-Abad🇺🇸 · JiJi Fan🇺🇸 · John Shing Chau Leung🇺🇸

    We entertain the exotic possibility that dark matter (DM) decays or annihilations taking place in our galaxy may produce a flux of relativistic very weakly-coupled bosons, axions or dark photons. We show that there exist several upper bounds for this flux on Earth assuming generic minimal requirements for DM, such as a lifetime longer than the age of the Universe or an annihilation rate that leaves unaffected the background evolution during matter domination. These bounds do not depend on the identity or the couplings of the bosons. We then show that this new flux cannot be large enough to explain the recent XENON1T excess, while assuming that the bosons' couplings to the Standard Model are consistent with all current experimental and observational constraints. We also discuss a possible caveat to these bounds and a route to explain the excess.

    hep-phastro-ph.COastro-ph.HEJCAP(2020)·56 citations
31. 31*

    Axion-mediated forces, CP violation and left-right interactions

    Stefano Bertolini🇮🇹 · Luca Di Luzio🇩🇪 · Fabrizio Nesti🇮🇹

    We compute the CP-violating (CPV) scalar axion coupling to nucleons in the framework of baryon chiral perturbation theory and we apply the results to the case of left-right symmetry. The correlated constraints with other CPV observables show that the predicted axion nucleon coupling is within the reach of present axion-mediated force experiments for $M_{W_R}$ up to $1000$ TeV.

    hep-phPRL(2021)·35 citations
32. 32*

    Charm jets as a probe for strangeness at the future Electron-Ion Collider

    Miguel Arratia🇺🇸 · Yulia Furletova🇺🇸 · T. J. Hobbs🇺🇸 · Fredrick Olness🇺🇸 · Stephen J. Sekula🇺🇸

    We explore the feasibility of the measurement of charm-jet cross sections in charged-current deep-inelastic scattering at the future Electron-Ion Collider. This channel provides clean sensitivity to the strangeness content of the nucleon in the high-$x$ region. We estimate charm-jet tagging performance with parametrized detector simulations. We show the expected sensitivity to various scenarios for strange parton distribution functions. We argue that this measurement will be key to future QCD global analyses, so it should inform EIC detector designs and luminosity requirements.

    hep-phhep-exnucl-exnucl-thPRD(2021)·43 citations
33. 33*

    Constraining the energy spectrum of neutral pions in ultra-high-energy proton-air interactions

    Lorenzo Cazon🇵🇹 · Ruben Conceição🇵🇹 · Miguel Alexandre Martins🇵🇹 · Felix Riehn🇵🇹

    Fluctuations in the muon content of extensive air showers are anticorrelated to the fluctuations of the energy taken by the neutral pions which emerge from the first interaction of the cosmic ray in the atmosphere. We show that the high-energy tail of the neutral pion spectrum produced in the first proton-air interaction can be constrained, within the uncertainties of present cosmic ray experiments, through the analysis of the shower-to-shower distribution of the muon content of the air showers, $P(N_{\mu })$.

    ↳ astro-ph.HEhep-phPRD(2021)·15 citations
34. 34*

    An effective field theory approach to monopolium

    L. M. Abreu🇧🇷 · M. de Montigny🇨🇦 · P. P. A. Ouimet🇨🇦

    In this work we investigate the interaction between spin-zero and spin-one monopoles by making use of an effective field theory based on two-body and four-body interaction parts. In particular, we analyze the formation of bound state of monopole-antimonopole (i.e. monopolium). The magnetic-charge conjugation symmetry is studied in analogy to the usual charge conjugation to define a particle basis, for which we find bound-state solutions with relatively small binding energies and which allows us to identify the bounds on the parameters in the effective Lagrangians. Estimations of their masses, binding energies and scattering lengths are performed as functions of monopole masses and interaction strength in a specific renormalization scheme. We also examine the general validity of the approach and the feasibility of detecting the monopolium.

    ↳ hep-thhep-phEur.Phys.J.Plus(2020)·3 citations
35. 35*

    Towards the Classification of Tachyon-Free Models From Tachyonic Ten-Dimensional Heterotic String Vacua

    Alon E. Faraggi🇬🇧 · Viktor G. Matyas🇬🇧 · Benjamin Percival🇬🇧

    Recently it was proposed that ten-dimensional tachyonic string vacua may serve as starting points for the construction of viable four dimensional phenomenological string models which are tachyon free. This is achieved by projecting out the tachyons in the four-dimensional models using projectors other than the projector which is utilised in the supersymmetric models and those of the $SO(16)\times SO(16)$ heterotic string. We continue the exploration of this class of models by developing systematic computerised tools for their classification, the analysis of their tachyonic and massless spectra, as well as analysis of their partition functions and vacuum energy. We explore a randomly generated space of $2\times 10^9$ string vacua in this class and find that tachyon--free models occur with $\sim 5\times 10^{-3}$ probability, and of those, phenomenologically inclined $SO(10)$ vacua with $a_{00}=N_b^0-N_f^0=0$, i.e. equal number of fermionic and bosonic massless states, occur with frequency $\sim 2\times 10^{-6}$. Extracting larger numbers of phenomenological vacua therefore requires adaptation of fertility conditions that we discuss, and significantly increase the frequency of tachyon--free models. Our results suggest that spacetime supersymmetry may not be a necessary ingredient in phenomenological string models, even at the Planck scale.

    ↳ hep-thhep-phNPB(2020)·40 citations
36. 36*

    Feasibility and physics potential of detecting ${}^8$B solar neutrinos at JUNO

    JUNO collaboration: Angel Abusleme · Thomas Adam · Shakeel Ahmad · Sebastiano Aiello · Muhammad Akram · Nawab Ali · Fengpeng An · Guangpeng An · Qi An · Giuseppe Andronico · Nikolay Anfimov · Vito Antonelli and 584 other authors

    The Jiangmen Underground Neutrino Observatory~(JUNO) features a 20~kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent experiment for ${}^8$B solar neutrino measurements, such as its low-energy threshold, its high energy resolution compared to water Cherenkov detectors, and its much large target mass compared to previous liquid scintillator detectors. In this paper we present a comprehensive assessment of JUNO's potential for detecting ${}^8$B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2~MeV threshold on the recoil electron energy is found to be achievable assuming the intrinsic radioactive background ${}^{238}$U and ${}^{232}$Th in the liquid scintillator can be controlled to 10${}^{-17}$~g/g. With ten years of data taking, about 60,000 signal and 30,000 background events are expected. This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter, which will shed new light on the tension between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework. If $\Delta m_{21}^2=4.8\times 10^{-5}(7.5\times 10^{-5})$~eV${}^2$, JUNO can provide evidence of neutrino oscillation in the Earth at the about 3$\sigma$~(2$\sigma$) level by measuring the non-zero signal rate variation with respect to the solar zenith angle. Moveover, JUNO can simultaneously measure $\Delta m_{21}^2$ using ${}^8$B solar neutrinos to a precision of 20\% or better depending on the central value and to sub-percent precision using reactor antineutrinos. A comparison of these two measurements from the same detector will help elucidate the current tension between the value of $\Delta m_{21}^2$ reported by solar neutrino experiments and the KamLAND experiment.

    ↳ hep-exhep-phphysics.ins-detCPC(2021)·85 citations
37. 37*

    The Geometrical Origin of Dark Energy

    Alon E. Faraggi🇬🇧 · Marco Matone🇮🇹

    The geometrical formulation of the quantum Hamilton-Jacobi theory shows that the quantum potential is never trivial, so that it plays the rôle of intrinsic energy. Such a key property selects the Wheeler-DeWitt (WDW) quantum potential $Q[g_{jk}]$ as the natural candidate for the dark energy. This leads to the WDW Hamilton-Jacobi equation with a vanishing kinetic term, and with the identification $$\Lambda =-\frac{{\kappa }^2}{\sqrt{\bar{g}}}Q[g_{jk}].$$ This shows that the cosmological constant is a quantum correction of the Einstein tensor, reminiscent of the von Weizsäcker correction to the kinetic term of the Thomas-Fermi theory. The quantum potential also defines the Madelung pressure tensor. The geometrical origin of the vacuum energy density, a strictly non-perturbative phenomenon, provides strong evidence that it is due to a graviton condensate. Time independence of the regularized WDW equation suggests that the ratio between the Planck length and the Hubble radius may be a time constant, providing an infrared/ultraviolet duality. We speculate that such a duality is related to the local to global geometry theorems for constant curvatures, showing that understanding the universe geometry is crucial for a formulation of Quantum Gravity.

    ↳ hep-thastro-ph.COgr-qchep-ph+1EPJC(2020)·16 citations
38. 38*

    Origin & evolution of the Universe

    Darsh Kodwani🇬🇧

    The aim of this thesis is to question some of the basic assumptions that go into building the $\Lambda$CDM model of our universe. The assumptions we focus on are the initial conditions of the universe, the fundamental forces in the universe on large scales and the approximations made in analysing cosmological data. For each of the assumptions we outline the theoretical understanding behind them, the current methods used to study them and how they can be improved and finally we also perform numerical analysis to quantify the novel solutions/methods we propose to extend the previous assumptions.

    ↳ astro-ph.COgr-qchep-ph0 citations
39. 39*

    The scalar sunset diagram at finite temperature with imaginary square masses

    Duifje Maria van Egmond🇧🇷 · Urko Reinosa🇫🇷

    We evaluate the finite temperature scalar sunset diagram with imaginary square masses, that appears in the Gribov-Zwanziger approach to Yang-Mills (YM) theory beyond one-loop order. Since YM theory at finite temperature is governed by center-symmetry and the Polyakov loop, we also include the possibility of a constant temporal background gauge field in the form of color-dependent imaginary chemical potentials.

    ↳ hep-thhep-lathep-phPRD(2020)·1 citation
40. 40*

    Relative entropy in scattering and the S-matrix bootstrap

    Anjishnu Bose🇮🇳 · Parthiv Haldar🇮🇳 · Aninda Sinha🇮🇳 · Pritish Sinha🇮🇳 · Shaswat S Tiwari🇮🇳

    We consider entanglement measures in 2-2 scattering in quantum field theories, focusing on relative entropy which distinguishes two different density matrices. Relative entropy is investigated in several cases which include ${\varphi }^4$ theory, chiral perturbation theory ($\chi PT$) describing pion scattering and dilaton scattering in type II superstring theory. We derive a high energy bound on the relative entropy using known bounds on the elastic differential cross-sections in massive QFTs. In $\chi PT$, relative entropy close to threshold has simple expressions in terms of ratios of scattering lengths. Definite sign properties are found for the relative entropy which are over and above the usual positivity of relative entropy in certain cases. We then turn to the recent numerical investigations of the S-matrix bootstrap in the context of pion scattering. By imposing these sign constraints and the $\rho$ resonance, we find restrictions on the allowed S-matrices. By performing hypothesis testing using relative entropy, we isolate two sets of S-matrices living on the boundary which give scattering lengths comparable to experiments but one of which is far from the 1-loop $\chi PT$ Adler zeros. We perform a preliminary analysis to constrain the allowed space further, using ideas involving positivity inside the extended Mandelstam region, and elastic unitarity.

    ↳ hep-thhep-phquant-phSciPost Phys.(2020)·61 citations
41. 41*

    Light nuclei production in Au + Au collisions at $\sqrt{s_{NN}}$ = 7.7-80 GeV from UrQMD model

    X. G. Deng🇨🇳 · Y. G. Ma🇨🇳

    Light nuclei production in relativistic ${}^{197}$Au + ${}^{197}$Au collisions from 7.7 to 80 GeV is investigated within the Ultra-relativistic-Quantum-Molecular-Dynamics model (UrQMD) with a naive coalescence approach. The results of the production of light nuclei at midrapidity can essentially match up the experimental data and a slight enhancement of combined ratio of $N_p{N}_t/N_d^2$ where $N_p,N_d$ and $N_t$ represent respectively the yields of proton, deuteron and triton, which is sensitive to the neutron density fluctuations, occurs around 20 GeV. However, this enhanced $N_p{N}_t/N_d^2$ ratio should not be over-understood considering that the present UrQMD model is a cascade version without equation of state (EoS), i.e. there is an absence of critical end point mechanism. Furthermore, within different rapidity regions, the kinetic temperatures of different light nuclei are extracted by the Blast-wave model analysis and ratios among different light nuclei are also discussed.

    ↳ nucl-thhep-phnucl-exPLB(2020)·22 citations
42. 42*

    Origins of the method to determine the CKM angle $\gamma$ using $B^{\pm }\to D{K}^{\pm }$, $D\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ decays

    A. Ceccucci🇨🇭 · T. Gershon🇬🇧 · M. Kenzie🇬🇧 · Z. Ligeti🇺🇸 · Y. Sakai🇯🇵 · K. Trabelsi🇫🇷

    The angle $\gamma$ of the Cabibbo--Kobayashi--Maskawa unitarity triangle is a benchmark parameter of the Standard Model of particle physics. A method to determine $\gamma$ from $B^{\pm }\to D{K}^{\pm }$ with subsequent $D\to K_{\mathrm{S}}^0{\pi }^{+}{\pi }^{-}$ or similar multibody decays has been proven to provide good sensitivity. We review the first discussions on the use of this technique, and its impact subsequently. We propose that this approach should be referred to as the BPGGSZ method.

    ↳ physics.hist-phhep-exhep-ph10 citations
43. 43*

    The Hubble Tension in Light of the Full-Shape Analysis of Large-Scale Structure Data

    Guido D'Amico🇮🇹 · Leonardo Senatore🇺🇸 · Pierre Zhang🇨🇳 · Henry Zheng🇺🇸

    The disagreement between direct late-time measurements of the Hubble constant from the SH0ES collaboration, and early-universe measurements based on the $\Lambda$CDM model from the Planck collaboration might, at least in principle, be explained by new physics in the early universe. Recently, the application of the Effective Field Theory of Large-Scale Structure to the full shape of the power spectrum of the SDSS/BOSS data has revealed a new, rather powerful, way to measure the Hubble constant and the other cosmological parameters from Large-Scale Structure surveys. In light of this, we analyze two models for early universe physics, Early Dark Energy and Rock 'n' Roll, that were designed to significantly ameliorate the Hubble tension. Upon including the information from the full shape to the Planck, BAO, and Supernovae measurements, we find that the degeneracies in the cosmological parameters that were introduced by these models are well broken by the data, so that these two models do not significantly ameliorate the tension.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·193 citations
44. 44*

    Spin Hall effect in heavy ion collisions

    Shuai Y.F. Liu🇨🇳 · Yi Yin🇨🇳

    Spin Hall effect (SHE) is the generation of spin current due to an electric field, and has been observed in a variety of materials. The analogous spin Hall current can be induced by chemical potential and temperature gradient, both of which are present in hot and dense nuclear matter created in heavy-ion collisions. In this letter, we investigate the perspective of detecting spin Hall current experimentally. We propose to measure "directed spin flow", the first Fourier coefficients of local spin polarization of $\Lambda$ ($\bar{\Lambda }$) hyperon, at central collisions to probe spin Hall current. To quantify induced spin current, we evaluate relevant transport coefficients using thermal field theory. We benchmark the magnitude of the induced "directed spin flow" at two representatively collisions energies, namely ${\sqrt{s}}_{NN}=200\mathrm{GeV}$ and ${\sqrt{s}}_{NN}=19.6\mathrm{GeV}$, by employing a phenomenologically motivated freeze-out prescription. At both beam energies, the resulting "directed spin flow" ranges from $10^{-4}$ to $10^{-3}$, and is very sensitive to the rapidity.

    ↳ nucl-thhep-phnucl-exPRD(2021)·95 citations
45. 45*

    Temperature dependence of $\eta /s$ of strongly interacting matter: effects of the equation of state and the parametric form of $(\eta /s)(T)$

    Jussi Auvinen🇷🇸 · Kari J. Eskola🇫🇮 · Pasi Huovinen🇷🇸 · Harri Niemi🇫🇮 · Risto Paatelainen🇨🇭 · Peter Petreczky🇺🇸

    We investigate the temperature dependence of the shear viscosity to entropy density ratio $\eta /s$ using a piecewise linear parametrization. To determine the optimal values of the parameters and the associated uncertainties, we perform a global Bayesian model-to-data comparison on Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV and Pb+Pb collisions at $2.76$ TeV and $5.02$ TeV, using a 2+1D hydrodynamical model with the EKRT initial state. We provide three new parametrizations of the equation of state (EoS) based on contemporary lattice results and hadron resonance gas, and use them and the widely used $s95p$ parametrization to explore the uncertainty in the analysis due to the choice of the equation of state. We found that $\eta /s$ is most constrained in the temperature range $T\approx 150$--$220$ MeV, where, for all EoSs, $0.08<\eta /s<0.23$ when taking into account the 90% credible intervals. In this temperature range the EoS parametrization has only a small $\approx 10\%$ effect on the favored $\eta /s$ value, which is less than the $\approx 30\%$ uncertainty of the analysis using a single EoS parametrization. Our parametrization of $(\eta /s)(T)$ leads to a slightly larger minimum value of $\eta /s$ than the previously used parametrizations. When we constrain our parametrization to mimic the previously used parametrizations, our favored value is reduced, and the difference becomes statistically insignificant.

    ↳ nucl-thhep-phPRC(2020)·70 citations
46. 46*

    The GCE in a New Light: Disentangling the $\gamma$-ray Sky with Bayesian Graph Convolutional Neural Networks

    Florian List🇦🇺 · Nicholas L. Rodd🇺🇸 · Geraint F. Lewis🇦🇺 · Ishaan Bhat🇳🇱

    A fundamental question regarding the Galactic Center Excess (GCE) is whether the underlying structure is point-like or smooth. This debate, often framed in terms of a millisecond pulsar or annihilating dark matter (DM) origin for the emission, awaits a conclusive resolution. In this work we weigh in on the problem using Bayesian graph convolutional neural networks. In simulated data, our neural network (NN) is able to reconstruct the flux of inner Galaxy emission components to on average $\sim$0.5%, comparable to the non-Poissonian template fit (NPTF). When applied to the actual $\text{Fermi}$-LAT data, we find that the NN estimates for the flux fractions from the background templates are consistent with the NPTF; however, the GCE is almost entirely attributed to smooth emission. While suggestive, we do not claim a definitive resolution for the GCE, as the NN tends to underestimate the flux of point-sources peaked near the 1$\sigma$ detection threshold. Yet the technique displays robustness to a number of systematics, including reconstructing injected DM, diffuse mismodeling, and unmodeled north-south asymmetries. So while the NN is hinting at a smooth origin for the GCE at present, with further refinements we argue that Bayesian Deep Learning is well placed to resolve this DM mystery.

    ↳ astro-ph.HEastro-ph.COastro-ph.IMcs.LG+1PRL(2020)·56 citations
47. 47*

    Weak Gravity Conjecture in de Sitter space-time

    Ignatios Antoniadis🇫🇷 · Karim Benakli🇫🇷

    We propose a generalisation of the Weak Gravity Conjecture in de Sitter space by studying charged black-holes and comparing the gravitational and an abelian gauge forces. Using the same condition as in flat space, namely the absence of black-hole remnants, one finds that for a given mass $m$ there should be a state with a charge $q$ bigger than a minimal value $q_{\min }(m,l)$, depending on the mass and the de Sitter radius $l$, in Planck units. In the large radius flat space limit (large $l$), $q_{\min }\to m$ leading to the known result $q>m/\sqrt{2}$, while in the highly curved case (small $l$) $q_{\min }$ behaves as $\sqrt{ml}$. We also discuss the example of the gauged R-symmetry in $N=1$ supergravity.

    ↳ hep-thgr-qchep-phFortsch.Phys.(2020)·31 citations
48. 48*

    Velocity-dependent Self-interacting Dark Matter from Groups and Clusters of Galaxies

    Laura Sagunski🇩🇪 · Sophia Gad-Nasr🇺🇸 · Brian Colquhoun🇨🇦 · Andrew Robertson🇬🇧 · Sean Tulin🇨🇦

    We probe the self-interactions of dark matter using observational data of relaxed galaxy groups and clusters. Our analysis uses the Jeans formalism and considers a wider range of systematic effects than in previous work, including adiabatic contraction and stellar anisotropy, to robustly constrain the self-interaction cross section. For both groups and clusters, our results show a mild preference for a nonzero cross section compared with cold collisionless dark matter. Our groups result, $\sigma /m=0.5\pm 0.2{\mathrm{cm}}^2/\mathrm{g}$, places the first constraint on self-interacting dark matter (SIDM) at an intermediate scale between galaxies and massive clusters. Our clusters result is $\sigma /m=0.19\pm 0.09{\mathrm{cm}}^2/\mathrm{g}$, with an upper limit of $\sigma /m<0.35{\mathrm{cm}}^2/\mathrm{g}$ (95% CL). Thus, our results disfavor a velocity-independent cross section of order $1{\mathrm{cm}}^2/\mathrm{g}$ or larger needed to address small scale structure problems in galaxies, but are consistent with a velocity-dependent cross section that decreases with increasing scattering velocity. Comparing the cross sections with and without the effect of adiabatic contraction, we find that adiabatic contraction produces slightly larger values for our data sample, but they are consistent at the $1\sigma$ level. Finally, to validate our approach, we apply our Jeans analysis to a sample of mock data generated from SIDM-plus-baryons simulations with $\sigma /m=1{\mathrm{cm}}^2/\mathrm{g}$. This is the first test of the Jeans model at the level of stellar and lensing observables directly measured from simulations. We find our analysis gives a robust determination of the cross section, as well as consistently inferring the true baryon and dark matter density profiles.

    ↳ astro-ph.COhep-phJCAP(2021)·155 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.