Tue·Jan 18, 2022Tuesday·January 18, 2022

1. 01*

   Reconciling LSND and super-Kamiokande data through the dynamical Lorentz symmetry breaking in a four-Majorana fermion model

   Y. M. P. Gomes🇧🇷 · M. J. Neves🇧🇷

   We propose a model of Majorana fermions with quartic self-couplings. These Majorana fermions acquire masses via a type II seesaw mechanism in which the physical eigenstates are identified as a light Majorana fermion and another heavy Majorana fermion. On a physical basis, the quartic self-couplings involve axial currents of these Majorana fermions, and also the interaction of the axial current for the light particle with the heavy particle one. We introduce two auxiliaries gauge fields in this model, and we study the stability conditions of the correspondent effective potential of the model. The ground state of the effective potential introduces two 4-vectors as scales of vacuum expected values, and consequently, the dynamical Lorentz symmetry breaking (DLSB) emerges in the model. We use the expansion of the effective action to calculate the effective Lagrangian up to second order in the auxiliary fields as fluctuations around the ground state. This mechanism generates dynamics for the auxiliary gauge fields, mixed mass terms, longitudinal propagation, and Chern-Simons term through radiative corrections. After the diagonalization, the two gauge fields gain masses through an analogous type II seesaw mechanism in which a gauge boson has a light mass, and the other one acquires a heavy mass. In this scenario of Lorentz symmetry breaking, we obtain the correspondent dispersion relations for the Majorana fermions and the gauge boson fields. Posteriorly, we analyze the neutrino's oscillations in the presence of a DLSB parameter, in the transition ${\nu }_e\to {\nu }_{\mu }$. We discuss the parameter space of this transition and show that the DLSB can conciliate the LSND and super-Kamiokande results.

   hep-phhep-thPRD(2022)·4 citations
2. 02*

   Light Quarks at Large $N$

   Daniel Davies🇺🇸 · Michael Dine🇺🇸 · Benjamin V. Lehmann🇺🇸

   Lattice gauge theory simulations are our principal probe of the masses of the light quarks. Results from such computations are the primary evidence against the $m_u=0$ solution to the strong CP problem. The large-$N$ approximation offers an independent approach to light quarks. We extend existing literature, noting that one can determine the parameters of the non-linear sigma model through second order in quark mass, rule out the $m_u=0$ hypothesis, and make predictions for outputs of lattice calculations and phenomenological fits. A crucial feature of this analysis is a Wilsonian effective action at scales above the ${\eta }^{\prime }$ mass. One can self-consistently test the validity of aspects of this framework, and it may well be good to the part-in-three level. We also note consistency with some phenomenological fits and existing lattice results.

   hep-phhep-lathep-th4 citations
3. 03*

   $b$-hadron spectroscopy study based on the similarity of double bottom baryon and bottom meson

   Bing Chen🇨🇳 · Si-Qiang Luo🇨🇳 · Ke-Wei Wei🇨🇳 · Xiang Liu🇨🇳

   The dynamical similarity which exists between the $\lambda$-mode excited $bbq$ baryons ($q$ refers to the $u$, $d$, and $s$ quarks) and the $\bar{b}q$ mesons inspires us to carry out a combined study of their spectroscopy. In this work, the masses and strong decays of these low-lying $b\bar{q}$ and $bbq$ states are studied by the same theoretical methods, and the dynamical similarity which is implied in their mass spectra and strong decays are also discussed. The recent discovered $\bar{b}q$ states, including the $B_J(5840)$, $B_J(5970)$, $B_{sJ}(6064)$, and $B_{sJ}(6114)$, are analyzed. According to our result, the $B_J(5840)$ could be assigned as a 2$S$ state, while the $B_J(5970)$ could be regarded as a member of the $1D(2^{-},3^{-}{)}_{j_q=5/2}$ doublet. The $B_{sJ}(6064)$ and $B_{sJ}(6114)$ are probably the $D$-wave states. Especially, they could be explained as the members of the $1D(1^{-},2^{-}{)}_{j_q=3/2}$ and $1D(2^{-},3^{-}{)}_{j_q=5/2}$ doublets, respectively. The predicted masses and decay properties of other unknown $\bar{b}q/bbq$ states may provide useful clues to the future experiment.

   hep-phPRD(2022)·29 citations
4. 04*

   Laser-assisted doubly charged Higgs pair production in Higgs triplet model (HTM)

   J. Ou aali🇲🇦 · M. Ouali🇲🇦 · M. Ouhammou🇲🇦 · S. Taj🇲🇦 · B. Manaut🇲🇦 · L. Rahili🇲🇦

   In the framework of Higgs triplet model (HTM), we study the pair production process of doubly charged Higgs bosons via $e^{+}{e}^{-}$ annihilation in the presence of a laser field with circular polarization . We begin our work by presenting the theoretical calculation of the differential cross section in the centre of mass frame including both $Z$ and $\gamma$ diagrams. Then, from the numerical analysis of the production cross section's dependence on the laser field parameters, we have shown that the laser-assisted total cross section decreases as far as the electromagnetic field intensity enhances or by decreasing its frequency. Finally, we analyze the variation of the total cross section versus the mass of the doubly charged Higgs boson by fixing the laser field parameters and the centre of mass energy, and we have found that the order of magnitude of the cross section decreases as long as $M_{H^{\pm \pm }}$ increases.

   hep-phEur.Phys.J.Plus(2022)·5 citations
5. 05*

   Verification of Bethe-Bloch formula using Geant4 toolkit

   Vanshaj Kerni🇮🇳 · Jyothsna Rani Komaragiri🇮🇳

   Understanding the physical world is a continuous process of trial and error. It requires theoretical background and tools to find out the theory's accuracy. Particles motion through matter, and their energy loss is one such process. Testing the energy loss requires the development of a tool capable of simulating and testing theoretical predictions using data. For this very reason, researchers developed a Monte-Carlo based simulation toolkit, the Geant4 project. A multi-purpose toolkit to explore the nature of collisions and energy loss of particles. Uses of Geant4 are in fields where particle interaction is required, ranging from high energy physics to medical physics and space physics research. Its physics component offers various simulations packages and tools to study the processes involved. The study uses the electromagnetic package to verify the Bethe-Bloch energy loss formula for charged particles developed mainly by Hans Bethe and analyse the extent of its validity.

   hep-ph0 citations
6. 06*

   Simulation of the Polarized Quark Fragmentation with Vector Meson Production

   Albi Kerbizi🇮🇹 · Xavier Artru🇫🇷 · Anna Martin🇮🇹

   The recently developed quantum mechanical string+${}^3{P}_0$ model of polarized quark fragmentation with pseudoscalar and vector meson production has been implemented in a stand alone Monte Carlo program. The simulation enables the detailed study of the quark spin dependent effects in the fragmentation process such as the transverse spin asymmetries. In particular, it allows to investigate the effects of the production and decay of vector mesons on the Collins and dihadron asymmetries of the observed hadrons, and to study the still unknown Collins effect for vector mesons. The main results of the Monte Carlo simulations obtained so far are summarized and the comparison with the existing experimental data on SIDIS and $e^{+}{e}^{-}$ annihilation to hadrons processes are presented.

   hep-phJPS Conf.Proc.(2022)·0 citations
7. 07*

   Monojet search for heavy neutrinos at future $Z$-factories

   Yin-Fa Shen🇨🇳 · Jian-Nan Ding🇨🇳 · Qin Qin🇨🇳

   The existence of heavy neutrinos is the most prominent feature of type-I seesaw-like mechanisms, which naturally explain tiny masses of observed neutrinos. Various experiments have been conducted to search for heavy neutrinos, with meson decays sensitive to heavy neutrinos lighter than $B$ mesons and high energy collider experiments sensitive to the ones with masses larger than $\mathcal{O}(0.1)$ TeV. In between, there is a mass gap uncovered by these two kinds of experiments, and by this work, we investigate the 3-15 GeV neutrino searches at future $Z$-factories via the process $e^{-}{e}^{+}\to Z\to \nu N\to \nu \ell \bar{q}{q}^{\prime }$ with $\ell =e,\mu$. Based on the simulation of signal and background events, we find that the signals appear as monojet events owning to the large Lorentz boost of the heavy neutrinos. Furthermore, the substructures of such monojet are essential to reconstruct the signal and suppress the background. The upper bounds on the cross section of the signal process and the mixing parameter ${|V_{\ell N}|}^2$ are obtained. Compared with other experiments, the monojet method at future $Z$-factories will be able to fill the gap around this mass range.

   hep-phhep-exEPJC(2022)·24 citations
8. 08*

   $J/\psi$ associated production with a bottom quark pair from the Higgs boson decay in next-to-leading order QCD

   Xue-An Pan🇨🇳 · Zhong-Ming Niu🇨🇳 · Mao Song🇨🇳 · Yu Zhang🇨🇳 · Gang Li🇨🇳 · Jian-You Guo🇨🇳

   In this work, we investigate the next-to-leading order (NLO) QCD correction to $J/\psi$ associated production with a bottom quark pair from the Higgs boson decay within the nonrelativistic QCD framework. From numerical results, {we find that the decay width of process $H\to b+J/\psi +\bar{b}$ at leading order (LO) mainly comes from the contribution of the Fock state ${}^3{S}_1^{(8)}$, and the NLO QCD corrections significantly enhance the decay width at LO accuracy by about 2 times. At NLO accuracy, the Fock states ${}^3{S}_1^{(8)}$ and ${}^3{P}_J^{(8)}$ channels give the main contribution, accounting for about $68\%$ and $29\%$ of the total decay width of $J/\psi$ associated production with a bottom quark pair at NLO accuracy from the Higgs boson decay, respectively. Considering the dominant contribution of color octet (CO) channels at NLO accuracy, the inclusive decay process $H\to b+J/\psi +\bar{b}+X$ has the potential to be found in future colliders with high energy/luminosity.} The study of $J/\psi$ associated production with a bottom quark pair from the Higgs boson decay is not only useful to study the mechanism of color-octet, but also to assist in the investigation of the coupling for the Higgs boson with the bottom quark.

   hep-phPRD(2022)·7 citations
9. 09*

   Forward-backward asymmetries in ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ in Bethe-Salpeter equation approach

   Liang-Liang Liu🇨🇳 · Su-Jun Cui🇨🇳 · Jing Xu🇨🇳 · Xin-Heng Guo🇨🇳

   Using the Bethe-Salpeter equation (BSE) we investigate the forward-backward asymmetries $(A_{FB})$ in ${\Lambda }_b\to \Lambda l^{+}{l}^{-}(l=e,\mu ,\tau )$ in the quark-diquark model. This approach provides precise form factors that are different from those of QCD sum rules. We calculate the rare decay form factors for ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ and investigate the (integrated) forward-backward asymmetries in these decay channels. We find that the integrated $A_{FB}^l$, ${\bar{A}}_{FB}^l({\Lambda }_b\to \Lambda e^{+}{e}^{-})\simeq -0.1371$, ${\bar{A}}_{FB}^l({\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-})\simeq -0.1376$, ${\bar{A}}_{FB}^l({\Lambda }_b\to \Lambda {\tau }^{+}{\tau }^{-})\simeq -0.1053$, the hadron side asymmetries ${\bar{A}}_{FB}^h({\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-})\simeq -0.2315$, the lepton-hadron side asymmetries ${\bar{A}}_{FB}^{lh}({\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-})\simeq 0.0827$, the longitudinal polarization fractions ${\bar{F}}_L({\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-})\simeq 0.5681$.

   hep-phCPC(2022)·1 citation
10. 10*

    $\bar{B}\to D^{\ast }{\ell }^{-}{\bar{\nu }}_{\ell }$ Decays: Angular Distributions and New Physics

    David London🇨🇦

    At the present time, there are hints of new physics (NP) in several observables involving $b\to c{\ell }^{-}{\bar{\nu }}_{\ell }$ decays. In this talk, I describe measurable angular distributions for $\bar{B}\to D^{\ast }{\mu }^{-}{\bar{\nu }}_{\mu }$ and $\bar{B}\to D^{\ast }{\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decays, including the most general NP contributions. These angular distributions contain enough information to pin down the Lorentz structure of the NP, which will help to identify it. They also have the ability to reveal the presence of non-SMEFT (non-decoupling) NP.

    hep-phPoS(2023)·0 citations
11. 11*

    The applicability of hydrodynamics in heavy ion collisions at $\sqrt{s_{\mathrm{NN}}}$= 2.4-7.7 GeV

    Gabriele Inghirami🇩🇪 · Hannah Elfner🇩🇪

    To assess the degree of equilibration of the matter created in heavy-ion reactions at low to intermediate beam energies, a hadronic transport approach (SMASH) is employed. By using a coarse-graining method, we compute the energy momentum tensor of the system at fixed time steps and evaluate the degree of isotropy of the diagonal terms and the relative magnitude of the off-diagonal terms. This study focuses mostly on Au+Au collisions in the energy range $\sqrt{s_{\mathrm{NN}}}$ = 2.4-7.7 GeV, but central collisions of lighter ions like C+C, Ar+KCl and Ag+Ag are considered as well. We find that the conditions concerning local equilibration for a hydrodynamic description are reasonably satisfied in a large portion of the system for a significant amount of time (several fm/c) when considering the average evolution of many events, yet they are rarely fulfilled on an event by event basis. This is relevant for the application of hybrid approaches at low beam energies as they are or will be reached by the HADES experiment at GSI, the future CBM experiment at FAIR as well as the beam energy scan program at RHIC.

    hep-phnucl-thEPJC(2022)·29 citations
12. 12*

    Light mesons with one dynamical gluon within basis light-front quantization

    Jiangshan Lan🇨🇳 · Kaiyu Fu🇨🇳 · Chandan Mondal🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

    We investigate the structure of the light meson with one dynamical gluon from the light-front QCD Hamiltonian, determined for their constituent quark-antiquark and quark-antiquark-gluon Fock sectors, together with a three-dimensional confinement. After fitting the light meson mass spectroscopy, the light-front wave functions provide a good quality description of the pion electromagnetic form factor, and the valence quark distribution functions following QCD scale evolution.

    hep-phnucl-th3 citations
13. 13*

    Geometry of the neutrino mixing space

    Wojciech Flieger🇩🇪 · Janusz Gluza🇵🇱

    We study a geometric structure of a physical region of neutrino mixing matrices as part of the unit ball of the spectral norm. Each matrix from the geometric region is a convex combination of unitary PMNS matrices. The disjoint subsets corresponding to a different minimal number of additional neutrinos are described as relative interiors of faces of the unit ball. We determined the Carathéodory's number showing that, at most, four unitary matrices of dimension three are necessary to represent any matrix from the neutrino geometric region. For matrices which correspond to scenarios with one and two additional neutrino states, the Carathéodory's number is two and three, respectively. Further, we discuss the volume associated with different mathematical structures, particularly with unitary and orthogonal groups, and the unit ball of the spectral norm. We compare the obtained volumes to the volume of the region of physically admissible mixing matrices for both the CP-conserving and CP-violating cases in the present scenario with three neutrino families and scenarios with the neutrino mixing matrix of dimension higher than three.

    hep-phhep-thPRD(2022)·2 citations
14. 14*

    Comparison of spin-correlation and polarization variables of spin density matrix for top quark pairs at the LHC and New Physics implications

    Altan Cakir🇹🇷 · Orcun Kolay🇹🇷

    Precise determination of top-quark pairs is an essential tool for understanding the overall consistency of the standard model (SM) expectations, understanding limited New Physics (NP) models, through spin-spin correlation and polarization parameters, and has a critical impact on the analyses strategies at upcoming LHC programs. In this work, we review and discuss various state-of-the-art Monte Carlo (MC) methodologies as \textsc{MadGraph5}\_aMC@NLO, \textsc{Sherpa}, \textsc{Powheg-Box} and \textsc{Pythia8}, which are Matrix Element (ME)$/$Parton Shower (PS) matching generators including a complete set of spin correlation and polarization in top quark pair production with dileptonic final states. This is the first such study that not only compares the effects of different MC event generator approaches on spin density matrix elements and polarization parameters, but also investigates the effects of leading order (LO) and next-to-leading order (NLO) accuracy in QCD, and electroweak (EW) corrections via \textsc{Sherpa}. Moreover, as a continuation of the work, the prospects for possible NP scenarios through top-quark spin-spin correlation and polarization measurements for Supersymmetry (R parity conserved and violated models) and Dark Matter (top quarks associated mediator) models during upcoming LHC runs are briefly outlined. We find that all SM MC predictions for the defined set of variables are generally consistent with the experimental data and theoretical predictions within the uncertainty variations. Besides, for the distributions of the $\cos \phi$, laboratory-frame observables ($\cos {\phi }_{lab}$ and $|\Delta {\varphi }_{ll}|$) and the observables generated by parity (P) and charge-parity (CP) conserving interactions, we conclude some clues that the considered signals and beyond may well be separated from experimental data and located above the SM predictions.

    hep-ph2 citations
15. 15*

    Strong and electromagnetic decays of the radially excited $D_s$ and $B_s$ mesons in light cone QCD sum rules

    S.Bilmis🇹🇷

    Recently, LHCb Collaboration announced the discovery of radial excitations of $D_s$ and $B_s$ mesons. In present work, we calculate the most promising strong and electromagnetic decay widths of radially excited $D_s(2S)$ and $B_s(2S)$ mesons within the light cone QCD sum rules method.

    hep-phEPJC(2021)·1 citation
16. 16*

    Mixing angles between the tetraquark states with two heavy quarks within QCD sum rules

    S.Bilmis🇹🇷

    LHCb Collaboration has recently announced the observation of a doubly charmed tetraquark $T_{cc\bar{u}\bar{d}}^{+}$ state with spin parity $J^P=1^{+}$. This exotic state can be explained as a molecular state with small binding energy. According to conventional quark model, both $D^{+}{D}^{0\ast }$ and $(D^0{D}^{+\ast })$ multiquark states are expected to have the same mass and flavor in the exact $SU(3)$ symmetry. However, since the quark masses are different, $SU(3)(SU(2))$ symmetry is violated, hence, the mass and flavor eigenstates do not coincide. The mass eigenstates can be represented as a linear combination of the flavor eigenstates, which is characterized by the mixing angle $\theta$. In the present work, the possible mixing angles between the $T_{cc}$ states are calculated. Moreover, the analysis are extended for all the possible tetraquarks scenarios with two heavy and two light quarks within the molecular picture although those states have not been observed yet. Our prediction on mixing angle between doubly charmed tetraquark states shows that $SU(3)$ symmetry breaking is around $7\%$ maximally.

    hep-phTurk.J.Phys.(2021)·5 citations
17. 17*

    Unitarity and Finkelstein-Kajantie problem in diffraction hadron production

    E. Martynov🇺🇦 · G. Tersimonov🇺🇦

    The diffraction production of many hadron showers separated by large rapidity gaps, when calculated within the standard pomeron approach, lead to cross sections rising much faster than Froissart-Martin bound. This is the point of Finkelstein-Kajantie problem. We consider the unitarization procedure based on Dyson-Schwinger equations with input froissaron propagators and 3-froissaron vertex (3f-vertex) depending on angular momenta of froissarons in it. The developed diffraction production model allows to resolve Finkelstein-Kajantie problem.

    hep-phhep-exPRD(2022)·1 citation
18. 18*

    Elastic meson form factors in a unified scheme

    R. J. Hernández-Pinto🇲🇽 · M. Bedolla-Hernández🇲🇽 · L. X. Gutiérrez-Guerrero🇲🇽 · A. Bashir🇲🇽

    The extraction of elastic form factors for mesons in the context of the contact interaction model is revisited in this manuscript. The dressed masses of quarks and mesons are determined through the gap and Bethe-Salpeter equations. The generic elastic scattering process $M\gamma \to M$ is studied for the meson $M$ formed of two differently flavored quarks. The charge radii of scalar, pseudoscalar, vector and axial-vector mesons are also extracted by virtue of explicit calculation of the meson elastic form factors.

    hep-phRev.Mex.Fis.Suppl.(2022)·3 citations
19. 19*

    Neutrino Mass from Affleck-Dine Leptogenesis and WIMP Dark Matter

    Rabindra N. Mohapatra🇺🇸 · Nobuchika Okada🇺🇸

    Affleck-Dine (AD) mechanism for leptogenesis involves the cosmological evolution of a complex scalar field (AD field) that carries non-zero lepton number. We show how explicit lepton number breaking terms, which involve the AD field needed to implement this scenario combined with fermionic WIMP dark matter, can generate neutrino mass at the one loop level, thus providing a unified framework for solving four major puzzles of the standard model i.e. inflation, baryogenesis, dark matter and neutrino mass. We discuss some phenomenological implications of this model.

    hep-phJHEP(2022)·15 citations
20. 20*

    Charge-dependent directed flows in heavy-ion collisions by Boltzmann-Maxwell equations

    Jun-Jie Zhang🇨🇳 · Xin-Li Sheng🇨🇳 · Shi Pu🇨🇳 · Jian-Nan Chen🇨🇳 · Guo-Liang Peng🇨🇳 · Jian-Guo Wang🇨🇳 · Qun Wang🇨🇳

    We have calculated the directed flow $v_1$ and charge-dependent directed flow $\Delta v_1$ for pions and protons in Au+Au collisions at $\sqrt{s_{NN}}=200$GeV by solving the coupled Boltzmann-Maxwell equations self-consistently. Our numerical results show that $v_1$ for pions and protons are all negative in the positive mid rapidity region and have similar behavior and magnitude. In contrast we find a quite different behavior in $\Delta v_1$ for pions and protons. The difference lies in that $\Delta v_1$ for protons mainly comes from pressure gradients of the medium, while the dominant contribution to $\Delta v_1$ for pions is from electromagnetic fields. Our results indicate that the effect of the electric field will slightly exceed that of the magnetic and lead to a small negative slope of $\Delta v_1$ for pions

    hep-phnucl-thPRResearch(2022)·23 citations
21. 21*

    Muon g-2 and other observables in models with extended Higgs and matter sectors

    Radovan Dermisek🇺🇸

    I review possible explanations of the muon g-2 anomaly in models with extended Higgs and matter sectors, focusing on extensions of the standard model and the two Higgs doublet model with vectorlike leptons. Predictions of these models, namely the modifications of muon Yukawa and gauge couplings, that can be searched for at the LHC and future colliders, are summarized. I also discuss striking predictions for di-Higgs and tri-Higgs signals at a muon collider that can be tested even at very low energies. Furthermore, I briefly comment on other interesting features and signatures of models with extended Higgs sector and vectorlike matter.

    hep-phMoscow Univ.Phys.Bull.(2022)·6 citations
22. 22*

    Transverse positron polarization in the polarized ${\mu }^{+}$ decay related with the muonium-to-antimuonium transition

    Takeshi Fukuyama🇯🇵 · Yukihiro Mimura🇯🇵 · Yuichi Uesaka🇯🇵

    The constructions of the new high-intensity muon beamlines are progressing in facilities around the world, and new physics searches related to the muons are expected. The facilities can observe the transverse positron polarization of the polarized ${\mu }^{+}$ decay to test the standard model. The transition of muonium into antimuonium (Mu-to-$\overline{\text{Mu}}$ transition), which is one of the interesting possibilities in the models beyond the standard model, can be also tested. The near-future observation of the transition gives us a great impact since it indicates that there is an approximate discrete symmetry in the lepton sector. If the Mu-to-$\overline{\text{Mu}}$ transition operator is generated, a new muon decay operator can exist and it may interfere with the standard model muon decay operator to induce the corrections to the transverse positron polarization in the ${\mu }^{+}$ decay. In this paper, we examine the possibility that the Mu-to-$\overline{\text{Mu}}$ transition and the correction to the transverse positron polarization are related, and we show that those two are related in the model of a neutral flavor gauge boson. We also investigate the models to generate the Mu-to-$\overline{\text{Mu}}$ transition, such as an inert $SU(2{)}_L$ doublet, a $SU(2{)}_L$ triplet for the type-II seesaw model, a dilepton gauge boson, and a left-right model. The non-zero value of the transverse polarization for one of the two directions, $P_{{\mathrm{T}}_2}$, violates the time-reversal invariance, and the experimental constraint of the electron electric dipole moment can provide a severe constraint on $P_{{\mathrm{T}}_2}$ depending on the model.

    hep-phPRD(2022)·3 citations
23. 23*

    Hyperfine splitting effects in string hadronization

    Christian Bierlich🇸🇪 · Smita Chakraborty🇸🇪 · Gösta Gustafson🇸🇪 · Leif Lönnblad🇸🇪

    We revisit the recipe for hadron formation in the Lund string hadronization model. Given an incoming quark or quark-diquark pair, weights for hadron formation are updated to take hyperfine splitting effects arising from the mass difference between u, d-type and s-type quarks. We find that the procedure improves the description of hadron yields in ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ collisions and the $\varphi$ cross section in neutral current DIS. We also show results for proton collisions, and discuss the future use of this study in the context of small system collectivity.

    hep-phEPJC(2022)·12 citations
24. 24*

    Identifying the contribution of higher $\rho$ mesons around 2 GeV in the $e^{+}{e}^{-}\to \omega {\pi }^0$ and $e^{+}{e}^{-}\to \rho {\eta }^{\prime }$ processes

    Qin-Song Zhou🇨🇳 · Jun-Zhang Wang🇨🇳 · Xiang Liu🇨🇳 · Takayuki Matsuki🇯🇵

    The properties of the light vector meson states around 2.0 GeV have been poorly understood for a long time, which has become a barrier to the expansion to higher light vector meson spectrum. Recently, the BESIII collaboration released the measurements of the $e^{+}{e}^{-}\to \omega {\pi }^0$ and $e^{+}{e}^{-}\to \rho {\eta }^{\prime }$ reactions above 2.0 GeV, both of which are ideal processes to study the isovector $\rho$ meson family. In this work, through carrying out a combined analysis of the Born cross section data for the above two processes with the theoretical support on mass spectrum, and production and strong decay behaviors of the $\rho$ meson family around 2.0 GeV, we identify the enhancement structure near 2034 MeV observed in $e^{+}{e}^{-}\to \omega {\pi }^0$ to be the interference contribution from two resonances $\rho (1900)$ and $\rho (2150)$, and another enhancement structure at 2111 MeV reported in $e^{+}{e}^{-}\to \rho {\eta }^{\prime }$ to be the contributions from $\rho (2000)$ and $\rho (2150)$. This conclusion means that the $e^{+}{e}^{-}\to \omega {\pi }^0$ and $e^{+}{e}^{-}\to \rho {\eta }^{\prime }$ are the excellent golden channels to establish $\rho (1900)$ and $\rho (2000)$, especially for a $D$-wave state $\rho (2000)$, whose experimental search in the $e^{+}{e}^{-}$ collision should be quite challenging. The relevant cross section measurements with higher precision are expected in the future BESIII and Belle II experiments.

    hep-phhep-exPRD(2022)·12 citations
25. 25*

    Baryogenesis from combined Higgs - scalar field inflation

    Yann Cado🇪🇸 · Mariano Quirós🇪🇸

    We study a modification of the Higgs inflation scenario where we introduce an extra scalar $\varphi$, with mass $m$, coupled to the Ricci scalar as $g{\varphi }^{2}R$, and mixed with the Higgs field $h$ via the Lagrangian term $\mu \varphi h^2$. Both fields participate in the inflation process in a unitary theory that predicts values of the cosmological observables in agreement with the results from the Planck/BICEP/Keck collaborations. In addition, by means of a $\mathcal{C}\mathcal{P}$-odd effective operator that couples $\varphi$ to the Chern-Simons term of the hypercharge gauge group as $f_{\varphi }^{-1}\varphi Y_{\mu \nu }{\tilde{Y}}^{\mu \nu }$, maximally helical magnetic fields are produced during the last $e$-folds of inflation. We found a window in the coupling $f_{\varphi }$ where these fields survive all constraints until the electroweak phase transition, and source the baryon asymmetry of the Universe through the Standard Model chiral anomaly. From a phenomenological perspective, the model can solve the Standard Model instability problem at the scale ${\mathcal{Q}}_I\simeq 10^{11}$ GeV, provided that $\mu \lesssim m\lesssim {\mathcal{Q}}_I$, and for $m\lesssim \mathcal{O}$(few)~TeV, the $\varphi$-$h$ mixing becomes sizable while the theory turns natural. The latter thus predicts modifications of the trilinear and quartic couplings that could be explored at the HE-LHC, as well as at future colliders, and allows for direct $\varphi$ production at the LHC followed by decay into $hh$. Present results from ATLAS and CMS already put (mild) bounds on the mass of the heavy scalar as $m\gtrsim 0.55$~TeV at 95\% C.L.

    hep-phastro-ph.COhep-thPRD(2022)·15 citations
26. 26*

    All-charm tetraquark in front form dynamics

    Zhongkui Kuang🇨🇳 · Kamil Serafin🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

    We study all-charm tetraquarks in the front form of Hamiltonian dynamics using the many-body basis function approach known as basis light-front quantization. The model Hamiltonian contains transverse and longitudinal confining potentials and a one-gluon-exchange effective potential. We calculate masses of two-charm-two-anticharm states focusing on the lowest state. We also calculate two-quark and four-quark estimates of meson-meson breakup threshold. The results suggest that the lowest two-charm-two-anticharm state is not a tightly bound tetraquark. We discuss implications of the cluster decomposition principle for theories formulated on the light front and present our treatment of identical particles together with color-singlet restrictions on the space of quantum states.

    hep-phPRD(2022)·37 citations
27. 27*

    Momentum distributions of cosmic relics: Improved analysis

    Kalle Ala-Mattinen🇫🇮 · Matti Heikinheimo🇫🇮 · Kimmo Kainulainen🇫🇮 · Kimmo Tuominen🇫🇮

    We solve coupled momentum-dependent Boltzmann equations for the phase space distribution of cosmic relic particles, without resorting to approximations of assuming kinetic equilibrium or neglecting backscattering or elastic interactions. Our method is amendable to precision numerical computations. To test it, we consider two benchmark models where the momentum dependence of dark matter distribution function is potentially important: a real singlet scalar extension near the Higgs resonance and a sterile neutrino dark matter model with a singlet scalar mediator. The singlet scalar example shows that the kinetic equilibrium may hold surprisingly well even near sharp resonances. However, the integrated method may underestimate the relic density by up to 40% in extreme cases. In the sterile neutrino dark matter model, we studied how the inclusion of previously ignored elastic interactions and processes with initial state sterile neutrinos could affect the nonthermal nature of their resulting distributions. Here the effects turned out to be negligible, proving the robustness of the earlier predictions.

    hep-phastro-ph.COPRD(2022)·29 citations
28. 28*

    The decay of $N^{\ast }$(1895) to light hyperon resonances

    K. P. Khemchandani🇧🇷 · A. Martínez Torres🇧🇷 · Sang-Ho Kim🇰🇷 · Seung-il Nam🇰🇷 · H. Nagahiro🇯🇵 · A. Hosaka🇯🇵

    In this talk I review the findings of our recent works where we have studied the decay of $N^{\ast }(1895)$ and the implications of such properties on the photoproduction of light hyperons. I discuss that meson-baryon interactions play an essential role in describing the nature of $N^{\ast }(1895)$ and report the details of our investigation of its decays to different meson-baryon systems and to final states involving $\Lambda (1405)$ and a proposed $\Sigma (1400)$. We find that the width of $N^{\ast }(1895)$ gets important contributions from the decay to light hyperon resonances. Such an information can be used to look for alternative processes to study $N^{\ast }(1895)$ in experimental data.

    hep-phnucl-thRev.Mex.Fis.Suppl.(2022)·3 citations
29. 29*

    Electromagnetic spectral functions in hot and dense chirally imbalanced quark matter

    Snigdha Ghosh🇮🇳 · Nilanjan Chaudhuri🇮🇳 · Sourav Sarkar🇮🇳 · Pradip Roy🇮🇳

    The photon self-energy from chirally imbalanced quark matter is evaluated at finite temperature and density using the real time formulation of thermal field theory. The analytic structure is explored in detail exposing the cut structure which corresponds to a variety of physical scattering and decay processes in the medium and their thresholds. The mass of the quarks in the chiral symmetry broken phase are obtained from the gap equation of the Nambu--Jona-Lasinio model. It is found that, in presence of finite chiral chemical potential, the chiral condensate tends to get stronger at low temperature while the opposite is observed at high values of temperature. A continuous spectrum is obtained for the electromagnetic spectral function and this is purely a finite chiral chemical potential effect.

    hep-phnucl-thPRD(2022)·11 citations
30. 30*

    Dark matter self-interactions in the matter power spectrum

    Raghuveer Garani🇮🇹 · Michele Redi🇮🇹 · Andrea Tesi🇮🇹

    We study the imprints of secluded dark sectors with a mass gap and self-interactions on the matter power spectrum. When Dark Matter (DM) is sufficiently light, in the ballpark of a few KeV, and self-interacting we find qualitative difference with respect to $\Lambda$CDM and also to free streaming DM. In order to emphasize the role of interactions for the evolution of the primordial perturbations we discuss various regimes: ranging from the ideal case of a tightly coupled perfect fluid to the free case of Warm Dark Matter, including the realistic case of small but non-vanishing self-interactions. We compute the matter power spectrum in all these regimes with the aid of Boltzmann solvers. Light dark sectors with self-interactions are efficiently constrained by Lyman-$\alpha$ data and we find that the presence of self-interactions relaxes the bound on the DM mass. As a concrete realization we study models with dark QCD-like sectors, where DM is made of light dark-pions.

    hep-phastro-ph.COJCAP(2022)·7 citations
31. 31*

    Useful relations and sum rules for PDFs and multiparton distribution functions of spin-1 hadrons

    S. Kumano🇯🇵 · Qin-Tao Song🇨🇳

    There are two types of polarizations in spin-1 hadrons, and they are vector and tensor polarizations. The latter is a unique one since it does not exist in the spin-1/2 proton. The vector-polarized PDFs are the same for both the proton and spin-1 hadrons; therefore, we mainly investigate the unique PDFs in tensor-polarized hadrons. By using the operator product expansion, the twist-3 PDF $f_{LT}$ can be expressed by two terms in the same way with $g_T$ of the proton. The first term is determined by the twist-2 PDF $f_{1LL}$ (or $b_1$) which was measured by an experiment, and the second term is expressed by twist-3 quark-gluon distributions. If we neglect the higher-twist effects, $f_{LT}$ is simply given by $f_{1LL}$, and this relation is similar to the Wandzura-Wilczek relation of $g_T$. Furthermore, a new sum rule is also obtained for $f_{2LT}=2/3f_{LT}-f_{1LL}$, which is analogous to the Burkhardt-Cottingham sum rule, in the tensor-polarized spin-1 hadrons. In future, these interesting relations could be studied at accelerator facilities, such as the Jefferson Laboratory, the Fermilab, the nuclotron-based ion collider facility in Russia, the proposed electron-ion colliders in US and China.

    hep-phhep-latnucl-thJPS Conf.Proc.(2022)·0 citations
32. 32*

    Revival of $H^{-}$ interpretation of $R_{D^{(\ast )}}$ anomaly and closing low mass window

    Syuhei Iguro🇩🇪

    Thanks to the recent careful revisit of the theoretical prediction of the $B_c$ meson lifetime, the conservative upper bound on the branching ratio (BR) of $\tau \nu$ mode is found to be $\simeq 63\%$ due to the large charm quark mass uncertainty. Although it is well known that a charged Higgs ($H^{-}$) interpretation of the $R_{D^{(\ast )}}$ anomaly is excluded by the previously proposed bounds, BR$(B_c\to \tau \nu )\le 30\%$ and $\le 10\%$, $H^{-}$ can still explain the anomaly within $1\sigma$ if we adopt the 63$\%$ one. The scalar contribution is also favored by the polarization data $F_L^{D^{\ast }}$ measured at the Belle. Since the implied NP scale is within the reach of the Large Hadron Collider (LHC), collider searches are powerful tools to test the scenario. For instance, the $\tau \nu$ resonance search has already put the more stringent bound for $m_{H^{-}}\ge 400$GeV. In this work we revisit the further lighter mass range, $180$GeV$\le m_{H^{-}}\le 400$GeV which has not been covered yet. We will see that a combination of the conventional stau search and low mass flavor inclusive and bottom flavored di-jet resonance searches can place a new limit on the interpretation. We summarize the current status of the low mass region and discuss the future sensitivity in the high luminosity (HL)-LHC based on the existent collider constraints.

    hep-phhep-exPRD(2022)·43 citations
33. 33*

    Displaced or invisible? ALPs from $B$ decays at Belle II

    Torben Ferber🇩🇪 · Anastasiia Filimonova🇳🇱 · Ruth Schäfer🇩🇪 · Susanne Westhoff🇩🇪

    At colliders, neutral long-lived particles can be detected through displaced decay products or as missing energy. Which search strategy is better depends on the particle's decay length just as on the detector properties. We investigate the complementarity of displaced and invisible signatures for the Belle II experiment. Focusing on axion-like particles $a$ produced from meson decays, we present a new search strategy for two-body decays $B^{+}\to K^{+}a,a\to E/$ with missing energy $E/$. With $50$ab${}^{-1}$ of data, Belle II can probe light invisible resonances with branching ratio $\mathcal{B}(B^{+}\to K^{+}a)\gtrsim 10^{-7}$ and decay length $c{\tau }_a\gtrsim 1$m. For axion-like particles, we expect the sensitivity of $B^{+}\to K^{+}E/$ to small couplings to improve by up to two orders of magnitude compared to previous searches at collider and fixed-target experiments. For sub-GeV particles, $B^{+}\to K^{+}E/$ at Belle II and searches at beam-dump experiments are most sensitive; for heavier particles, searches for displaced vertices at Belle II, long-lived particle experiments at the LHC, and future fixed-target experiments can probe the smallest couplings.

    hep-phhep-exJHEP(2023)·54 citations
34. 34*

    Machine learning of log-likelihood functions in global analysis of parton distributions

    DianYu Liu🇨🇳 · ChuanLe Sun🇨🇳 · Jun Gao🇨🇳

    Modern analysis on parton distribution functions (PDFs) requires calculations of the log-likelihood functions from thousands of experimental data points, and scans of multi-dimensional parameter space with tens of degrees of freedom. In conventional analysis the Hessian approximation has been widely used for the estimation of the PDF uncertainties.The Lagrange Multiplier (LM) scan while being a more faithful method is less used due to computational limitations, and is the main focus of this study. We propose to use Neural Networks (NNs) and machine learning techniques to model the profile of the log-likelihood functions or cross sections for multi-dimensional parameter space in order to overcome those limitations which work beyond the quadratic approximations and meanwhile ensures efficient scans of the full parameter space. We demonstrate the efficiency of the new approach in the framework of the CT18 global analysis of PDFs by constructing NNs for various target functions, and performing LM scans on PDFs and cross sections at hadron colliders. We further study the impact of the NOMAD dimuon data on constraining PDFs with the new approach, and find enhanced strange-quark distributions and reduced PDF uncertainties. Moreover, we show how the approach can be used to constrain new physics beyond the Standard Model (BSM) by a joint fit of both PDFs and Wilson coefficients of operators in the SM effective field theory.

    hep-phhep-exJHEP(2022)·21 citations
35. 35*

    Chiral gauge theories and non-abelian analogues of axions

    P. Mitra🇮🇳

    The axion particle may or may not exist, but the axion field can be used, as shown here, in an explicitly local formulation of a chiral U(1) gauge theory with both classical and quantum gauge invariance. Nonabelian analogues of axion fields, which have recently been introduced, can be used, together with their special symmetries, in a similar construction of nonabelian chiral gauge theories. As in known cases, the gauge symmetry is broken and the gauge boson acquires a mass by swallowing the axions which are therefore not physical in this construction.

    hep-phhep-thNPB(2022)·0 citations
36. 36*

    High-Energy Neutrino Emission from Blazars

    Foteini Oikonomou🇳🇴

    Active galactic nuclei (AGN) with relativistic jets are the most powerful persistent astrophysical sources of electromagnetic radiation in the Universe. Blazars are the most extreme subclass of AGN with jets directed along the line of sight of the observer. Their high-energy photon emission dominates the extragalactic gamma-ray sky and reaches multi-TeV energies. This demonstrates that blazars accelerate particles to very high energies. It has long been suspected that blazars may also accelerate protons to very high energies and thus be cosmic neutrino sources. Being extremely rare objects in addition to being bright, blazars are among the most readily testable neutrino candidate source classes. Several multi-messenger monitoring campaigns have recently been triggered in response to high-energy neutrinos observed with the IceCube Neutrino Observatory from the direction of blazars. In this contribution, I summarise the theoretical interpretation of these observations and give an overview of the possible role of blazars as neutrino sources in light of the experimental results.

    ↳ astro-ph.HEhep-phPoS(2022)·17 citations
37. 37*

    Exotic Compact Objects: The Dark White Dwarf

    Michael Ryan🇺🇸 · David Radice🇺🇸

    Several dark matter models allow for the intriguing possibility of exotic compact object formation. These objects might have unique characteristics that set them apart from their baryonic counterparts. Furthermore, gravitational wave observations of their mergers may provide the only direct window on a potentially entirely hidden sector. Here we discuss dark white dwarfs, starting with an overview of the microphysical model and analytic scaling relations of macroscopic properties derived from the non-relativistic limit. We use the full relativistic formalism to confirm these scaling relations and demonstrate that dark white dwarfs, if they exist, would have masses and tidal deformabilities that are very different from those of baryonic compact objects. Further, and most importantly, we demonstrate that dark white dwarf mergers would be detectable by current or planned gravitational observatories across several orders of magnitude in the particle-mass parameter space. Lastly, we find universal relations analogous to the compactness-Love and binary Love relations in neutron star literature. Using these results, we show that gravitational wave observations would constrain the properties of the dark matter particles constituting these objects.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2022)·40 citations
38. 38*

    ${\rm Y}$ and ${\eta }_b$ nuclear bound states

    J. J. Cobos-Martínez🇲🇽 · G. N. Zeminiani🇧🇷 · K. Tsushima🇧🇷

    ${\rm Y}$ and ${\eta }_b$ nuclear bound state energies are calculated for various nuclei neglecting any possible effects of the widths. Essential input for the calculations, namely the medium-modified $B$ and $B^{\ast }$ meson masses, as well as the density distributions in nuclei, are calculated within the quark-meson coupling (QMC) model. The attractive potentials for the ${\rm Y}$ and ${\eta }_b$ mesons in nuclei are calculated from the mass shifts of these mesons in nuclear matter in the local density approximation. These potentials originate from the in-medium enhanced $B\overline{B}$ and $B{B}^{\ast }$ loops in their respective self energy. After an extensive analysis we conclude that our results suggest that the ${\rm Y}$ and ${\eta }_b$ mesons should form bound states with all the nuclei considered.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2022)·15 citations
39. 39*

    Renormalizing the vacuum energy in cosmological spacetime: implications for the cosmological constant problem

    Cristian Moreno-Pulido🇪🇸 · Joan Sola Peracaula🇪🇸

    The renormalization of the vacuum energy in quantum field theory (QFT) is usually plagued with theoretical conundrums related not only with the renormalization procedure itself, but also with the fact that the final result leads usually to very large (finite) contributions incompatible with the measured value of $\Lambda$ in cosmology. Herein, we compute the zero-point energy (ZPE) for a nonminimally coupled (massive) scalar field in FLRW spacetime using the off-shell adiabatic renormalization technique employed in previous work. The general off-shell result yields a smooth function ${\rho }_{\mathrm{vac}}(H)$ made out of powers of the Hubble rate and/or of its time derivatives involving different (even) adiabatic orders $\sim H^N$ ($N=0,2,4,6,...)$, i.e. it leads, remarkably enough, to the running vacuum model (RVM) structure. We have verified the same result from the effective action formalism and used it to find the $\beta$-function of the running quantum vacuum. No undesired contributions $\sim m^4$ from particle masses appear and hence no fine-tuning of the parameters is needed in ${\rho }_{\mathrm{vac}}(H)$. Furthermore, we find that the higher power $\sim H^6$ could naturally drive RVM-inflation in the early universe. Our calculation also elucidates in detail the equation of state of the quantum vacuum: it proves to be not exactly $-1$ and is moderately dynamical. The form of ${\rho }_{\mathrm{vac}}(H)$ at low energies is also characteristic of the RVM and consists of an additive term (the so-called `cosmological constant') together with a small dynamical component $\sim \nu H^2$ ($|\nu |\ll 1$). Finally, we predict a slow ($\sim \ln H$) running of Newton's gravitational coupling $G(H)$. The physical outcome of our semiclassical QFT calculation is revealing: today's cosmic vacuum and the gravitational strength should be both mildly dynamical.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2022)·111 citations
40. 40*

    Searching for wormholes with gravitational wave scattering

    Shou-shan Bao🇨🇳 · Shaoqi Hou🇨🇳 · Hong Zhang🇨🇳

    Wormholes bridging distant places of the universe are well-known solutions of general relativity. In particular, traversable wormholes which allow interstellar traveling are also popular in science fiction. However, no hint of their existence has been found yet. In this work, we propose using the gravitational wave (GW) scattering off spherical wormholes to search for their existence. We carefully calculate the reflected and transmitted waveforms with time-independent scattering theory. Our results quantitatively show the echo signatures in the two universes on both sides of the wormhole. In a certain wormhole mass range, the transmitted wave has a unique isolated chirp without an inspiral waveform, and the reflected wave has the anti-chirp behavior, i.e., the missing of the chirping signal. We also calculate the searching range of the current and projected GW telescopes. Our method can be adapted to efficiently calculate the templates to search for wormholes.

    ↳ gr-qcastro-ph.HEhep-phEPJC(2023)·16 citations
41. 41*

    Super-critical QED-effects via VP-energy

    K.Sveshnikov🇷🇺 · Yu.Voronina🇷🇺

    The properties of the QED-vacuum energy \hbox{\cal E }_{VP} under Coulomb super-criticality condition $Z>Z_{cr,1}$ are explored in essentially non-perturbative approach. It is shown that in the supercritical region \hbox{\cal E }_{VP} is the decreasing function of the Coulomb source parameters, resulting in decay into the negative range as $\sim -Z^4/R$. The conditions, under which the emission of vacuum positrons can be unambiguously detected on the nuclear conversion pairs background, are also discussed. In particular, for a super-critical dummy nucleus with charge $Z$ and $R(Z)\simeq 1.2(2.5Z{)}^{1/3}$ fm the lowest $1s$-level dives into the lower continuum at $Z_{cr,1}\simeq 170$ (the model of uniformly charged ball) or $Z_{cr,1}\simeq 173$ (the spherical shell model), whereupon there appears the vacuum shell with the induced charge (-$2|e|$) and the QED-vacuum becomes charged, but in both cases the actual threshold for reliable spontaneous positrons detection is not less than $Z^{\ast }\simeq 210$.

    ↳ physics.atom-phhep-ph0 citations
42. 42*

    Differential elastic nucleus-nucleus scattering in complete Glauber theory

    Yu.M. Shabelski🇷🇺 · A.G. Shuvaev🇷🇺

    The differential elastic cross sections of ${}^{12}$C -- ${}^{12}$C and ${}^{11}$Li -- ${}^{12}$C nuclei are calculated in the complete Glauber theory. The role of the possible correlations connected to the shell effects in ${}^{11}$Li nucleus is considered.

    ↳ nucl-thhep-phMod.Phys.Lett.A(2022)·2 citations
43. 43*

    Initial Energy of a Spatially Flat Universe -- a Hint of its Possible Origin

    Fulvio Melia🇺🇸

    The evidence for a Big Bang origin of the Universe is truly compelling, though its cause remains a complete mystery. As the cosmic spacetime is revealed to us with ever improving detail, however, we are beginning to refine the range of its possible initial conditions -- at least within the framework of current physical theories. The Universe, it seems, is spatially flat, and here we discuss in clear, straightforward terms why this trait implies a cosmos with zero kinetic plus gravitational energy, though apparently not zero total energy. Such an outcome has far reaching consequences because of the possibility that the Universe may have begun its existence as a quantum fluctuation. Was this from `nothing,' or perhaps a pre-existing vacuum? A non-zero total energy would seemingly preclude the former scenario, but not necessarily the latter, though this would then raise the question of how a fluctuation with non-zero energy could have lived long enough, or classicalized, for us to see it 13.5 billion years later. The high-precision measurement of the Universe's spatial curvature may thus constitute the first tangible piece of evidence impacting a possible quantum beginning.

    ↳ astro-ph.COgr-qchep-phAstron.Nachr.(2022)·6 citations
44. 44*

    Single-pion contribution to the Gerasimov--Drell--Hearn sum rule and related integrals

    Igor Strakovsky (GWU)🇺🇸 · Simon Širca (University of Ljubljana)🇸🇮 · William J. Briscoe (GWU)🇺🇸 · Alexandre Deur (JLab)🇺🇸 · Axel Schmidt (GWU)🇺🇸 · Ron L. Workman (GWU)🇺🇸

    Phenomenological amplitudes obtained in partial-wave analyses (PWA) of single-pion photoproduction are used to evaluate the contribution of this process to the Gerasimov-Drell-Hearn (GDH), Baldin and Gell-Mann-Goldberger-Thirring (GGT) sum rules, by integrating up to 2 GeV in photon energy. Our study confirms that the single-pion contribution to all these sum rules converges even before the highest considered photon energy, but the levels of saturation are very different in the three cases. Single-pion production almost saturates the GDH sum rule for the proton, while a large fraction is missing in the neutron case. The Baldin integrals for the proton and the neutron are both saturated to about four fifths of the predicted total strength. For the GGT sum rule, the wide variability in predictions precludes any definitive statement.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2022)·12 citations
45. 45*

    Gravitational search for near Earth black holes or other compact dark objects

    Tomoyo Namigata🇺🇸 · C. J. Horowitz🇺🇸 · R. Widmer-Schnidrig🇩🇪

    Primordial black holes, with masses comparable to asteroids, are an attractive possibility for dark matter. In addition, other forms of dark matter could form compact dark objects (CDO). We search for small tidal accelerations from low mass black holes or CDOs orbiting near the Earth, and find none. Using about 10 years of data from the superconducting gravimeters in the Black Forest Observatory in South-Western Germany and at Djougou, Northern Benin in Western Africa we set an upper limit on the maximum mass of any dark object orbiting the Earth as a function of orbital radius. For semi-major axis less than two earth radii we exclude all black holes or CDOs with masses larger than 6.7x10^{13} kg. Lower mass primordial black holes may be strongly constrained by Hawking radiation. We conclude that near Earth black holes are extremely unlikely.

    ↳ gr-qcastro-ph.COastro-ph.EPastro-ph.HE+25 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.