Wed·Jun 24, 2020Wednesday·June 24, 2020

1. 01*

   Prospects of Migdal Effect in the Explanation of XENON1T Electron Recoil Excess

   Ujjal Kumar Dey🇮🇳 · Tarak Nath Maity🇮🇳 · Tirtha Sankar Ray🇮🇳

   The XENON1T experiment has recently announced the observation of an excess in electron recoil events at energy range of $1-7$ keV with a $3.5\sigma$ signal significance over the Standard Model prediction. In this letter we sketch the prospects of explaining such an excess from Migdal ionization events with below threshold nuclear recoil energies. Interestingly, these are expected to show signal events in the ballpark energy scale of the observed excess. We demonstrate that the observed signal can be reproduced through the Migdal effect by an $\mathcal{O}(1)$ GeV neutron-philic dark matter having a spin-dependent coupling with the nucleus. A more optimistic scenario is explored where the Migdal ionization is driven by MeV scale boosted dark matter.

   hep-phastro-ph.HEPLB(2020)·66 citations
2. 02*

   A Somewhat Random Walk Through Nuclear and Particle Physics

   Thomas D. Cohen🇺🇸 · Nicholas R. Poniatowski🇺🇸

   These notes are an outgrowth of an advanced undergraduate course taught at the University of Maryland, College Park. They are intended as an introduction to various aspects of particle and nuclear physics with an emphasis on the role of symmetry. The basic philosophy is to introduce many of the fundamental ideas in nuclear and particle physics using relatively sophisticated mathematical tools -- but to do so in as a simplified a context to explain the underlying ideas. Thus, for example, the Higgs mechanism is discussed in terms of an Abelian Higgs model. The emphasis is largely, but not entirely theoretical in orientation. The goal is for readers to develop an understanding of many of the underlying issues in a relatively sophisticated way.

   hep-phhep-exnucl-exnucl-thSciPost Phys.Lect.Notes(2021)·0 citations
3. 03*

   A Critical Look at the Electroweak Phase Transition

   Andreas Ekstedt🇨🇿 · Johan Löfgren🇸🇪

   The electroweak phase transition broke the electroweak symmetry. Perturbative methods used to calculate observables related to this phase transition suffer from severe problems such as gauge dependence, infrared divergences, and a breakdown of perturbation theory. In this paper we develop robust perturbative tools for dealing with phase transitions. We argue that gauge and infrared problems are absent in a consistent power-counting. We calculate the finite temperature effective potential to two loops for general gauge-fixing parameters in a generic model. We demonstrate gauge invariance, and perform numerical calculations for the Standard Model in Fermi gauge.

   hep-phJHEP(2020)·45 citations
4. 04*

   The muon $g$-2 and $\Delta \alpha$ connection

   Alexander Keshavarzi🇬🇧 · William J. Marciano🇺🇸 · Massimo Passera🇮🇹 · Alberto Sirlin🇺🇸

   The discrepancy between the Standard Model theory and experimental measurement of the muon magnetic moment anomaly, $a_{\mu }=\left(g_{\mu }-2\right)/2$, is connected to precision electroweak (EW) predictions via their common dependence on hadronic vacuum polarization effects. The same data for the total $e^{+}{e}^{-}\to \text{hadrons}$ cross section, ${\sigma }_{\mathrm{had}}(s)$, are used as input into dispersion relations to estimate the hadronic vacuum polarization contributions, $a_{\mu }^{\mathrm{had},\mathrm{VP}}$, as well as the five-flavor hadronic contribution to the running QED coupling at the $Z$-pole, $\Delta {\alpha }_{\mathrm{had}}^{(5)}(M_Z^2)$, which enters natural relations and global EW fits. The EW fit prediction of $\Delta {\alpha }_{\mathrm{had}}^{(5)}(M_Z^2)=0.02722(41)$ agrees well with $\Delta {\alpha }_{\mathrm{had}}^{(5)}(M_Z^2)=0.02761(11)$ obtained from the dispersion relation approach, but exhibits a smaller central value suggestive of a larger discrepancy $\Delta a_{\mu }=a_{\mu }^{\exp }-a_{\mu }^{\mathrm{SM}}$ than currently expected. Postulating that the $\Delta a_{\mu }$ difference may be due to missing ${\sigma }_{\mathrm{had}}(s)$ contributions, implications for $M_W$, ${\sin }^2{\theta }_{\mathrm{eff}}^{\mathrm{lep}}$ and $M_H$ obtained from global EW fits are investigated. Shifts in ${\sigma }_{\mathrm{had}}(s)$ needed to bridge $\Delta a_{\mu }$ are found to be excluded above $\sqrt{s}\gtrsim 0.7$ GeV at the 95\%CL. Moreover, prospects for $\Delta a_{\mu }$ originating below that energy are deemed improbable given the required increases in the cross section. Such hypothetical changes to the hadronic data are also found to affect other related observables, such as the electron anomaly, $a_e^{\mathrm{SM}}$, the ratio $R_{e/\mu }=(m_{\mu }/m_e{)}^2(a_e^{\mathrm{had},\mathrm{LO}\mathrm{VP}}/a_{\mu }^{\mathrm{had},\mathrm{LO}\mathrm{VP}})$ and the running of the weak mixing angle at low energies, although the consequences of these are currently less constraining.

   hep-phhep-exPRD(2020)·237 citations
5. 05*

   Exploring for sub-MeV Boosted Dark Matter from Xenon Electron Direct Detection

   Qing-Hong Cao🇨🇳 · Ran Ding🇨🇳 · Qian-Fei Xiang🇨🇳

   Direct detection experiments turn to lose sensitivity of searching for a sub-MeV light dark matter candidate due to the threshold of recoil energy. However, such light dark matter particles can be accelerated by energetic cosmic-rays such that they can be detected with existing detectors. We derive the constraints on the scattering of a boosted light dark matter and electron from the XENON100/1T experiment. We illustrate that the energy dependence of the cross section plays a crucial role in improving both the detection sensitivity and also the complementarity of direct detection and other experiments.

   hep-phastro-ph.HEhep-exCPC(2021)·98 citations
6. 06*

   Dark Matter Search at Colliders and Neutrino Floor

   Qing-Hong Cao🇨🇳 · An-Kang Wei🇨🇳 · Qian-Fei Xiang🇨🇳

   The sensitivity of direct detection of dark matter (DM) approaches the so-called neutrino floor below which it is hard to disentangle the DM candidate from the background neutrino. In this work we consider the scenario that no DM signals are reported in various DM direct detection experiments and explore whether the collider searches could probe the DM under the neutrino floor. We adopt several simplified models in which the DM candidate couples only to electroweak gauge bosons or leptons in the standard model through high dimensional operators. After including the RGE running effect we investigate constraints from direct detection, indirect detection and collider searches. The collider search can probe a light DM below neutrino floor. Especially, for the effective interaction of $\bar{\chi }\chi B_{\mu \nu }{B}^{\mu \nu }$, current data of the mono-photon channel at the 13 TeV LHC has already covered entire parameter space of the neutrino floor.

   hep-phastro-ph.HEhep-exCPC(2020)·4 citations
7. 07*

   Next-to-leading-logarithm $k_T$ resummation for $B_c\to J/\psi$ decays

   Xin Liu🇨🇳 · Hsiang-nan Li🇹🇼 · Zhen-Jun Xiao🇨🇳

   We derive the $k_T$ resummation for a transverse-momentum-dependent charmonium wave function, which involves the bottom quark mass $m_b$, the charm quark mass $m_c$, and the charm quark transverse momentum $k_T$, up to the next-to-leading-logarithm (NLL) accuracy under the hierarchy $m_b\gg m_c\gg k_T$. The resultant Sudakov factor is employed in the perutrbative QCD (PQCD) approach to the $B_c\to J/\psi$ transition form factor $A_0^{B_c\to J/\psi }(0)$ and the $B_c^{+}\to J/\psi {\pi }^{+}$ decay. We compare the NLL resummation effect on these processes with the leading-logarithm one in the literature, and find a $(5-10)\%$ enhancement to the form factor $A_0^{B_c\to J/\psi }(0)$ and a $(10-20)\%$ enhancement to the decay rate $\mathrm{BR}(B_c^{+}\to J/\psi {\pi }^{+})$. The improved $k_T$ resummation formalism is applicable to the PQCD analysis of heavy meson decays to other charmonia.

   hep-phhep-exPLB(2020)·22 citations
8. 08*

   Loop-induced $ZZ$ production at the LHC: an improved description by matrix-element matching

   Congqiao Li🇨🇳 · Ying An🇨🇳 · Claude Charlot🇫🇷 · Roberto Covarelli🇮🇹 · Zhe Guan🇨🇳 · Qiang Li🇨🇳

   Loop-induced $ZZ$ production can be enhanced by the large gluon flux at the LHC, and thus should be taken into account in relevant experimental analyses. We present for the first time the results of a fully exclusive simulation based on the matrix elements for loop-induced $ZZ+0,1,2$-parton processes at leading order, matched to parton showers. The new description is studied and validated by comparing it with well-established simulation with jets from parton showers. We find that the matched simulation provides a state-of-the-art description of the final state jets. We also briefly discuss the physics impact on vector boson scattering (VBS) measurements at the LHC, where event yields are found to be smaller by about 40% in a VBS $ZZjj$ baseline search region, compared to previous simulations. We hence advocate relevant analyses to employ a more accurate jet description for the modeling of the loop-induced process.

   hep-phhep-exPRD(2020)·12 citations
9. 09*

   Can Nonstandard Neutrino Interactions explain the XENON1T spectral excess?

   Amir N. Khan🇩🇪

   We perform a constrained spectral fit analysis of the excess observed in the electron recoil energy spectrum by XENON1T with neutrino magnetic moment, charge radius, neutrino millicharge and new light vector and scalar mediators. Within the limits allowed by other laboratory experiments we find that the excess can be explained in the range$(2-4)\times 10^{-11}{\mu }_B$ for the magnetic moment,$(2-6)\times 10^{-31}$cm${}^2$ for the charge radius, $(1.7-2.3)\times 10^{-12}e$ for the millicharge and $(10-100)$keV masses of light mediators with couplings of $3.5\times 10^{-7}$ for vector/axial-vector, $1\times 10^{-6}$ and $4\times 10^{-6}$ for scalar and pseudo-scalar mediators respectively. Among all neutrino millicharge, magnetic moment and vector mediators fit better to the observed spectrum. We also derive constraints on all new physics parameters considered here.

   hep-phhep-exPLB(2020)·78 citations
10. 10*

    A new parton fragmentation procedure for heavy hadron production in proton-proton collisions

    Antoni Szczurek🇵🇱

    We propose a new procedure for parton-to-hadron fragmentation in proton-proton collisions. The hadronization is considered in the parton-parton center-of-mass system and hadrons are assumed to be emitted in the direction of outgoing partons in that frame and then their four-momenta are transformed to the overall center-of-mass system using relevant Lorentz transformations and appropriate distributions are constructed. For heavy hadron production the energy-momentum condition is imposed. In many cases our procedure disagrees with the commonly used rule that rapidity of produced hadron is the same as rapidity of the parent parton. We illustrate the newly proposed scheme for production of $D$ mesons, ${\Lambda }_c$ baryon and ${\eta }_c$ quarkonium in leading-order approach to parton production. The transverse momentum, rapidity and Feynman-$x_F$ distributions are shown. We consider $c\to D$ and $g\to D$ as well as $c\to {\eta }_c$ and $g\to {\eta }_c$ hadronization processes. The resulting rapidity distributions are much narrower than those obtained in the traditional approach with parton-hadron rapidity equivalence. This has consequences both for mid- and forward rapidities and could have consequences for high-energy neutrino production in the Earth's atmosphere. We discuss also $c\to {\Lambda }_c^{+}$ and $b\to {\Lambda }_c^{+}$ fragmentation and find that the second mechanism could be partly responsible for the enhanced production of ${\Lambda }_c^{\pm }$ observed recently by the ALICE collaboration.

    hep-phJ.Phys.G(2021)·4 citations
11. 11*

    Photonuclear $J/\psi$ production at the LHC: proton-based versus nuclear dipole scattering amplitudes

    D.Bendova🇨🇿 · J. Cepila🇨🇿 · J. G. Contreras🇨🇿 · M. Matas🇨🇿

    The coherent photonuclear production of a $J/\psi$ vector meson at the LHC has been computed using two different sets of solutions of the impact-parameter dependent Balitsky-Kovchegov equation. The nuclear dipole scattering amplitudes are obtained either from ($i$) solutions for this process off proton targets coupled with a Glauber-Gribov prescription, or ($ii$) from solutions obtained with an initial condition representing the nucleus. These approaches predict different cross sections, which are compared with existing data from ultra-peripheral collisions at the LHC. The latter approach seems to better describe current measurements. Future LHC data should be precise enough to select one of the two approaches as the correct one.

    hep-phPLB(2021)·60 citations
12. 12*

    OPE of Green Functions of Chiral Currents

    Tomas Kadavy🇨🇿 · Karol Kampf🇨🇿 · Jiri Novotny🇨🇿

    In this paper we investigate the high-energy behavior of two-point and three-point Green functions of the QCD chiral currents and densities using the framework of the operator product expansion in the chiral limit. In detail, we study the contributions of the quark, gluon, quark-gluon and four-quark condensates to all the relevant non-vanishing three-point correlators.

    hep-phJHEP(2020)·15 citations
13. 13*

    Tetraquark candidates in the LHCb's di-$J/\psi$ mass spectrum

    Zhi-Gang Wang🇨🇳

    In this article, we study the first radial excited states of the scalar, axialvector, vector and tensor diquark-antidiquark type $cc\bar{c}\bar{c}$ tetraquark states with the QCD sum rules and obtain the masses and pole residues, then we use the Regge trajectory to obtain the masses of the second radial excited states. The predicted masses support assigning the broad structure from 6.2 to 6.8 GeV in the di-$J/\psi$ mass spectrum to be the first radial excited state of the scalar, axialvector, vector or tensor $cc\bar{c}\bar{c}$ tetraquark state, and assigning the narrow structure at about 6.9 GeV in the di-$J/\psi$ mass spectrum to be the second radial excited state of the scalar or axialvector $cc\bar{c}\bar{c}$ tetraquark state.

    hep-phCPC(2020)·88 citations
14. 14*

    Optimized probes of $CP$-odd effects in the $t\bar{t}h$ process at hadron colliders

    Blaž Bortolato🇸🇮 · Jernej F. Kamenik🇸🇮 · Nejc Košnik🇸🇮 · Aleks Smolkovič🇸🇮

    We use machine learning (ML) and non-ML techniques to study optimized $CP$-odd observables, directly and maximally sensitive to the $CP$-odd $i\tilde{\kappa }\bar{t}{\gamma }^{5}th$ interaction at the LHC and prospective future hadron colliders using the final state with a Higgs boson and a top quark pair, $pp\to t\bar{t}h$, followed by semileptonic $t$ decays. We perform phase-space optimization of manifestly $CP$-odd observables ($\mathbf{\omega }$), sensitive to the sign of $\tilde{\kappa }$, and constructed from experimentally accessible final state momenta. We identify a simple optimized linear combination $\mathbf{\alpha }\cdot \mathbf{\omega }$ that gives similar sensitivity as the studied fully fledged ML models. Using $\mathbf{\alpha }\cdot \mathbf{\omega }$ we project the expected sensitivities to $\tilde{\kappa }$ at HL-LHC, HE-LHC, and FCC-hh.

    hep-phNPB(2021)·44 citations
15. 15*

    Primordial Black Holes from QCD Axion Bubbles

    Naoya Kitajima🇯🇵 · Fuminobu Takahashi🇯🇵

    We propose a scenario in which a strong Peccei-Quinn (PQ) symmetry breaking in the early universe results in large inhomogeneities of the initial QCD axion field value, leading to the formation of very dense axion bubbles. Some of the axion bubbles subsequently collapse into primordial black holes (PBHs). The spatially homogeneous part of the QCD axion explains dark matter of the universe, while the PBHs arising from the axion bubbles can explain the LIGO events or the seed of supermassive black holes. Interestingly, the mass of PBH is determined by the axion decay constant; for $f_a=10^{17}(10^{16})$ GeV, the PBH mass is heavier than about $10(10^4)M_{\odot }$. In addition, axion miniclusters are also formed from the axion bubbles more abundantly than PBHs, and their masses are expected to be heavier than in the usual scenario based on the spontaneous breaking of the PQ symmetry after inflation.

    hep-phastro-ph.COJCAP(2020)·58 citations
16. 16*

    Gravitational Production of Hidden Photon Dark Matter in Light of the XENON1T Excess

    Kazunori Nakayama🇯🇵 · Yong Tang🇨🇳

    Recently, the XENON1T experiment has reported an excess in the electronic recoil events. The excess is consistent with the interpretation of absorption of 3keV bosonic dark matter, for example, hidden photon dark matter with kinetic mixing of the order of $10^{-15}$. We point out that the minimally gravitational production provides a viable mechanism for obtaining a correct relic hidden photon abundance. We present parameter dependence of the hidden photon dark matter abundance on the inflationary scale $H_{\inf }$ and also the reheating temperature $T_{\mathrm{R}}$. We show that the inflationary Hubble scale and reheating temperature are both bounded from below, $H_{\inf }\gtrsim 7\times 10^{11}$GeV, $T_{\mathrm{R}}\gtrsim 10^2$GeV. In particular, the high-scale inflation is consistent with 3keV hidden photon dark matter.

    hep-phPLB(2020)·58 citations
17. 17*

    Collider Constraints on a Dark Matter Interpretation of the XENON1T Excess

    R. Primulando🇮🇩 · J. Julio🇮🇩 · P. Uttayarat🇹🇭

    In light of the excess in the low-energy electron recoil events reported by XENON1T, many new physics scenarios have been proposed as a possible origin of the excess. One possible explanation is that the excess is a result of a fast moving dark matter (DM), with velocity $v\sim 0.05-0.20$ and mass between 1 MeV and 10 GeV, scattering off an electron. Assuming the fast moving DM-electron interaction is mediated by a vector particle, we derive collider constraints on the said DM-electron interaction. The bounds on DM-electron coupling is then used to constrain possible production mechanisms of the fast moving DM. We find that the preferred mass of the vector mediator is relatively light ($\lesssim$ 1 GeV) and the coupling of the vector to the electron is much smaller than the coupling to the fast moving DM.

    hep-phastro-ph.COEPJC(2020)·34 citations
18. 18*

    Forward trijet production in p-p and p-Pb collisions at LHC

    Marcin Bury🇩🇪 · Andreas van Hameren🇵🇱 · Piotr Kotko🇵🇱 · Krzysztof Kutak🇵🇱

    We calculate various azimuthal angle distributions for three jets produced in the forward rapidity region with transverse momenta $p_T>20\mathrm{GeV}$ in proton-proton (p-p) and proton-lead (p-Pb) collisions at center of mass energy $5.02\mathrm{TeV}$. We use the multi-parton extension of the so-called small-$x$ Improved Transverse Momentum Dependent factorization (ITMD). We study effects related to change from the standard $k_T$-factorization to ITMD factorization as well as changes as one goes from p-p collision to p-Pb. We observe rather large differences in the distribution when we change the factorization approach, which allows to both improve the small-$x$ TMD gluon distributions as well as validate and improve the factorization approach. We also see significant depletion of the nuclear modification ratio, indicating a possibility of searches for saturation effects using trijet final states in a more exclusive way than for dijets.

    hep-phJHEP(2020)·10 citations
19. 19*

    Exothermic Dark Matter for XENON1T Excess

    Hyun Min Lee🇰🇷

    Motivated by the recent excess in the electron recoil from XENON1T experiment, we consider the possibility of exothermic dark matter, which is composed of two states with mass splitting. The heavier state down-scatters off the electron into the lighter state, making an appropriate recoil energy required for the Xenon excess even for the standard Maxwellian velocity distribution of dark matter. Accordingly, we determine the mass difference between two component states of dark matter to the peak electron recoil energy at about $2.5\mathrm{keV}$ up to the detector resolution, accounting for the recoil events over $E_R=2-3\mathrm{keV}$, which are most significant. We include the effects of the phase-space enhancement and the atomic excitation factor to calculate the required scattering cross section for the Xenon excess. We discuss the implications of dark matter interactions in the effective theory for exothermic dark matter and a massive $Z^{\prime }$ mediator and provide microscopic models realizing the required dark matter and electron couplings to $Z^{\prime }$.

    hep-phJHEP(2021)·75 citations
20. 20*

    Electromagnetic potentials and radiation of the Proca field created by a massless charge

    Renata Jora🇷🇴

    We study a theory less explored in the literature, that of a massive abelian gauge boson interacting with a massless fermion. In this framework we calculate the electromagnetic potentials created by a point like massless charge. We determine also the radiation associated with a change in the momentum of the charge in the low energy regime. The results show both similarities and discrepancies with respect to quantum electrodynamics.

    hep-ph1 citation
21. 21*

    Dark Radiation from Inflationary Fluctuations

    Gordan Krnjaic🇺🇸

    Light new vector bosons can be produced gravitationally through quantum fluctuations during inflation; if these particles are feebly coupled and cosmologically metastable, they can account for the observed dark matter abundance. However, in minimal anomaly free $U(1)$ extensions to the Standard Model, these vectors generically decay to neutrinos if at least one neutrino mass eigenstate is sufficiently light. If these decays occur between neutrino decoupling and CMB freeze out, the resulting radiation energy density can contribute to $\Delta N_{\mathrm{eff}}$ at levels that can ameliorate the Hubble tension and be discovered with future CMB and relic neutrino detection experiments. Since the additional neutrinos are produced from vector decays after BBN, this scenario predicts $\Delta N_{\mathrm{eff}}>0$ at recombination, but $\Delta N_{\mathrm{eff}}=0$ during BBN. Furthermore, due to a fortuitous cancellation, the contribution to $\Delta N_{\mathrm{eff}}$ is approximately mass independent.

    hep-phastro-ph.COPRD(2021)·8 citations
22. 22*

    Penguin contribution to width difference and CP asymmetry in $B_q$-${\bar{B}}_q$ mixing at order ${\alpha }_s^2{N}_f$

    Hrachia M. Asatrian🇦🇲 · Hrachya H. Asatryan🇦🇲 · Artyom Hovhannisyan🇦🇲 · Ulrich Nierste🇩🇪 · Sergey Tumasyan🇦🇲 · Arsen Yeghiazaryan🇦🇲

    We present new contributions to the decay matrix element ${\Gamma }_{12}^q$ of the $B_q$-${\bar{B}}_q$ mixing complex, where $q=d$ or $s$. Our new results constitute the order ${\alpha }_s^2{N}_f$ corrections to the penguin contributions to the Wilson coefficients entering ${\Gamma }_{12}^q$ with full dependence on the charm quark mass. This is the first step towards the prediction of the CP asymmetry $a_{\mathrm{fs}}^q$ quantifying CP violation in mixing at next-to-next-to-leading logarithmic order (NNLO) in quantum chromodynamics (QCD) and further improves the prediction of the width difference $\Delta {\Gamma }_q$ between the two neutral-meson eigenstates. We find a sizable effect from the non-zero charm mass and our partial NNLO result decreases the NLO penguin corrections to $a_{\mathrm{fs}}^q$ by 37\% and those to $\Delta {\Gamma }_q$ by 16\%. We further update the Standard-Model NLO predictions for $a_{\mathrm{fs}}^q$ and the ratio of the width and mass differences of the $B_q$ eigenstates: If we express the results in terms of the pole mass of the bottom quark we find $a_{\mathrm{fs}}^s=(2.07\pm 0.10)\cdot 10^{-5}$, $a_{\mathrm{fs}}^d=(-4.71\pm 0.24)\cdot 10^{-4}$, $\Delta {\Gamma }_s/\Delta M_s=(4.33\pm 1.26)\cdot 10^{-3}$, and $\Delta {\Gamma }_d/\Delta M_d=(4.48\pm 1.19)\cdot 10^{-3}$. In the $\overline{\mathrm{MS}}$ scheme these numbers read $a_{\mathrm{fs}}^s=(2.04\pm 0.11)\cdot 10^{-5}$, $a_{\mathrm{fs}}^d=(-4.64\pm 0.25)\cdot 10^{-4}$, $\Delta {\Gamma }_s/\Delta M_s=(4.97\pm 1.02)\cdot 10^{-3}$, and $\Delta {\Gamma }_d/\Delta M_d=(5.07\pm 0.96)\cdot 10^{-3}$.

    hep-phPRD(2020)·31 citations
23. 23*

    Potential model prediction of fully-heavy tetraquarks $QQ\bar{Q}\bar{Q}$ ($Q=c,b$)

    Gang Yang🇨🇳 · Jialun Ping🇨🇳 · Lianyi He🇨🇳 · Qing Wang🇨🇳

    The fully-heavy tetraquark states $QQ\bar{Q}\bar{Q}$ ($Q=c,b$) are systematically investigated by means of a nonrelativistic potential model. The model is based on the lattice QCD study of the two-body $Q\bar{Q}$ interaction, which exhibits a spin-independent Cornell potential along with a spin-spin interaction. The four-body problem is implemented with a highly accurate computational approach, the Gaussian expansion method. The complex scaling method is also employed so that the bound, resonance, and scattering states can be treated on the same footing. Complete set of the four-body configurations, including meson-meson, diquark-antidiquark, and K-type configurations, as well as their couplings, are considered for spin-parity quantum numbers $J^{PC}=0^{++}$, $1^{+-}$, and $2^{++}$ in the $S$-wave channel. No $S$-wave bound state is found either in the fully-charm tetraquark system or in the fully-bottom one. However, several narrow resonances, with widths less than 10 MeV in two-meson strong decay, are found in both of these two systems. For the fully-charm case, the recently reported resonance structures between 6.2 and 7.2 GeV in the di-$J/\psi$ invariant spectrum by the LHCb collaboration, can be well identified in our calculation. For the fully-bottom case, resonances with masses between 18.9 and 19.6 GeV are found. The predicted resonances can be further examined in future experiments.

    hep-ph61 citations
24. 24*

    Higher-form symmetries and 3-group in axion electrodynamics

    Yoshimasa Hidaka🇯🇵 · Muneto Nitta🇯🇵 · Ryo Yokokura🇯🇵

    We study higher-form symmetries in a low-energy effective theory of a massless axion coupled with a photon in $(3+1)$ dimensions. It is shown that the higher-form symmetries of this system are accompanied by a semistrict 3-group (2-crossed module) structure, which can be found by the correlation functions of symmetry generators of the higher-form symmetries. We argue that the Witten effect and anomalous Hall effect in the axion electrodynamics can be described in terms of 3-group transformations.

    ↳ hep-thcond-mat.str-elhep-phPLB(2020)·81 citations
25. 25*

    Universal location of the Yang-Lee edge singularity in O(N) theories

    Andrew Connelly🇺🇸 · Gregory Johnson🇺🇸 · Fabian Rennecke🇺🇸 · Vladimir Skokov🇺🇸

    We determine a previously unknown universal quantity, the location of the Yang-Lee edge singularity for the O($N$) theories in a wide range of $N$ and various dimensions. At large $N$, we reproduce the $N\to \infty$ analytical result on the location of the singularity and, additionally, we obtain the mean-field result for the location in $d=4$ dimensions. In order to capture the nonperturbative physics for arbitrary $N$, $d$ and complex-valued external fields, we use the functional renormalization group approach.

    ↳ cond-mat.stat-mechhep-phnucl-thPRL(2020)·64 citations
26. 26*

    Two-photon exchange from intermediate state resonances in elastic electron-proton scattering

    Jaseer Ahmed🇨🇦 · P. G. Blunden🇨🇦 · W. Melnitchouk🇺🇸

    We use a recently developed dispersive approach to compute the two-photon exchange (TPE) correction to elastic electron-proton scattering, including contributions from hadronic $J^P=1/2^{\pm }$ and $3/2^{\pm }$ resonant intermediate states below~1.8~GeV. For the transition amplitudes from the proton ground state to the resonant excited states we employ new exclusive meson electroproduction data from CLAS at $Q^2\lesssim 5$~GeV${}^2$, and we explore the effects of both fixed and dynamic widths for the resonances. Among the resonant states, the $N(1520)3/2^{-}$ becomes dominant for $Q^2\gtrsim 2$~GeV${}^2$, with a sign opposite to the comparably sized $\Delta (1232)3/2^{+}$ contribution, leading to an overall increase in the size of the TPE correction to the cross section relative to the nucleon only contribution at higher $Q^2$ values. The results are in good overall agreement with recent $e^{+}p$ to $e^{-}p$ cross section ratio and polarization transfer measurements, and provide compelling evidence for a resolution of the electric to magnetic form factor ratio discrepancy.

    ↳ nucl-thhep-phnucl-exPRC(2020)·33 citations
27. 27*

    Large-scale Simulations of Antihelium Production in Cosmic-ray Interactions

    Anirvan Shukla🇺🇸 · Amaresh Datta🇺🇸 · Philip von Doetinchem🇺🇸 · Diego-Mauricio Gomez-Coral🇺🇸 · Carina Kanitz🇩🇪

    The possibility of antihelium production in interaction of cosmic rays with the interstellar gas is studied using large-scale Monte Carlo simulations. For this purpose, an energy-dependent coalescence mechanism developed previously is extended to estimate the production of light antinuclei (${}^3\overline{\text{He}}$ and ${}^4\overline{\text{He}}$). The uncertainty in the coalescence parameter and its effect on the expected antiparticle flux is also investigated. The simulated background antihelium fluxes are found to be lower than the fluxes predicted by simplified models using numerical scaling techniques.

    ↳ astro-ph.HEhep-phnucl-thPRD(2020)·32 citations
28. 28*

    Sterile neutrino self-interactions: $H_0$ tension and short-baseline anomalies

    Maria Archidiacono🇮🇹 · Stefano Gariazzo🇪🇸 · Carlo Giunti🇮🇹 · Steen Hannestad🇩🇰 · Thomas Tram🇩🇰

    Sterile neutrinos with a mass in the eV range have been invoked as a possible explanation of a variety of short baseline (SBL) neutrino oscillation anomalies. However, if one considers neutrino oscillations between active and sterile neutrinos, such neutrinos would have been fully thermalised in the early universe, and would be therefore in strong conflict with cosmological bounds. In this study we first update cosmological bounds on the mass and energy density of eV-scale sterile neutrinos. We then perform an updated study of a previously proposed model in which the sterile neutrino couples to a new light pseudoscalar degree of freedom. Consistently with previous analyses, we find that the model provides a good fit to all cosmological data and allows the high value of $H_0$ measured in the local universe to be consistent with measurements of the cosmic microwave background. However, new high $\ell$ polarisation data constrain the sterile neutrino mass to be less than approximately 1 eV in this scenario. Finally, we combine the cosmological bounds on the pseudoscalar model with a Bayesian inference analysis of SBL data and conclude that only a sterile mass in narrow ranges around 1 eV remains consistent with both cosmology and SBL data.

    ↳ astro-ph.COhep-phJCAP(2020)·67 citations
29. 29*

    Understanding the energy dependence of $B_2$ in heavy ion collisions: Interplay of volume and space-momentum correlations

    Vincent Gaebel🇩🇪 · Michel Bonne🇩🇪 · Tom Reichert🇩🇪 · Ajdin Burnic🇧🇦 · Paula Hillmann🇩🇪 · Marcus Bleicher🇩🇪

    The deuteron coalescence parameter $B_2$ in proton+proton and nucleus+nucleus collisions in the energy range of $\sqrt{s_{NN}}=$ 900 - 7000 GeV for proton+proton and $\sqrt{s_{NN}}=$ 2 - 2760 GeV for nucleus+nucleus collisions is analyzed with the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport model, supplemented by an event-by-event phase space coalescence model for deuteron and anti-deuteron production. The results are compared to data by the E866, E877, PHENIX, STAR and ALICE experiments. The $B_2$ values are calculated from the final spectra of protons and deuterons. At lower energies, $\sqrt{s_{NN}}\le 20$ GeV, $B_2$ drops drastically with increasing energy. The calculations confirm that this is due to the increasing freeze-out volume reflected in $B_2\sim 1/V$. At higher energies, $\sqrt{s_{NN}}\ge 20$ GeV, $B_2$ saturates at a constant level. This qualitative change and the vanishing of the volume suppression is shown to be due to the development of strong radial flow with increasing energy. The flow leads to strong space-momentum correlations which counteract the volume effect.

    ↳ nucl-thhep-phEPJA(2021)·17 citations
30. 30*

    Fixing the non-relativistic expansion of the 1PM potential

    Gianluca Grignani🇮🇹 · Troels Harmark🇩🇰 · Marta Orselli🇮🇹 · Andrea Placidi🇮🇹

    We obtain a first order post-Minkowskian two-body effective potential whose post-Newtonian expansion directly reproduces the Einstein-Infeld-Hoffmann potential. Post-Minkowskian potentials can be extracted from on-shell scattering amplitudes in a quantum field theory of scalar matter coupled to gravity. Previously, such potentials did not reproduce the Einstein-Infeld-Hoffmann potential without employing a suitable canonical transformation. In this work, we resolve this issue by obtaining a new expression for the first-order post-Minkowskian potential. This is accomplished by exploiting the reference frame dependence that arises in the scattering amplitude computation. Finally, as a check on our result, we demonstrate that our new potential gives the correct scattering angle.

    ↳ hep-thgr-qchep-phJHEP(2020)·4 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.