Wed·Feb 24, 2021Wednesday·February 24, 2021

1. 01*

   Symmetry and decoupling in multi Higgs models

   Sérgio Carrôlo🇵🇹 · Jorge C. Romão🇵🇹 · João P. Silva🇵🇹 · Francisco Vazão🇵🇹

   We study the scalar sector of the most general multi Higgs doublet model satisfying explicitly an exact symmetry. We prove that such a model will exhibit decoupling if and only if the vacuum also satisfies the same symmetry. This general property is also shown independently and explicitly for three Higgs doublet models, by considering in detail all symmetry-constrained models and their possible vacua. We also discuss some specific characteristics of different decoupling patterns.

   hep-phPRD(2021)·18 citations
2. 02*

   Deconfinement Phase Transition in the $SU(3)$ Instanton-dyon Ensemble

   Dallas DeMartini🇺🇸 · Edward Shuryak🇺🇸

   Confinement remains one the most interesting and challenging nonperturbative phenomenon in non-Abelian gauge theories. Recent semiclassical (for SU(2)) and lattice (for QCD) studies have suggested that confinement arises from interactions of statistical ensembles of instanton-dyons with the Polyakov loop. In this work, we extend studies of semiclassical ensemble of dyons to the $SU(3)$ Yang-Mills theory. We find that such interactions do generate the expected first-order deconfinement phase transition. The properties of the ensemble, including correlations and topological susceptibility, are studied over a range of temperatures above and below $T_c$. Additionally, the dyon ensemble is studied in the Yang-Mills theory containing an extra trace-deformation term. It is shown that such a term can cause the theory to remain confined and even retain the same topological observables at high temperatures.

   hep-phnucl-thPRD(2021)·9 citations
3. 03*

   Resummation of quantum radiation reaction in plane waves

   Greger Torgrimsson🇩🇪

   We propose a new approach to obtain the momentum expectation value of an electron in a high-intensity laser, including multiple photon emissions and loops. We find a recursive formula that allows us to obtain the $\mathcal{O}({\alpha }^n)$ term from $\mathcal{O}({\alpha }^{n-1})$, which can also be expressed as an integro-differential equation. In the classical limit we obtain the solution to the Landau-Lifshitz equation to all orders. We show how spin-dependent quantum radiation reaction can be obtained by resumming both the energy expansion as well as the $\alpha$ expansion.

   hep-phPRL(2021)·49 citations
4. 04*

   Electron and Muon Anomalous Magnetic Moments in the Inverse Seesaw Extended NMSSM

   Junjie Cao🇨🇳 · Yangle He🇨🇳 · Jingwei Lian🇨🇳 · Di Zhang🇨🇳 · Pengxuan Zhu🇨🇳

   The recently improved observation of the fine structure constant has led to a negative $2.4\sigma$ anomaly of electron $g-2$. Combined with the long-existing positive $4.2\sigma$ discrepancy of the muon anomalous magnetic moment, it is interesting and difficult to explain these two anomalies with a consistent model without introducing flavor violations. We show that they can be simultaneously explained in the inverse seesaw extended next-to-minimal supersymmetric standard model (ISS-NMSSM) by the Higgsino--sneutrino contributions to $(g-2{)}_e$ and $(g-2{)}_{\mu }$. The spectrum features prefer light $\mu$, which can predict $m_Z$ naturally, and it is not difficult to obtain a $\tau$-type sneutrino dark matter candidate that is compatible with the observed dark matter relic density and the bounds from dark matter direct detection experiments. Due to the compressed spectra and the undetectable decay mode of selectrons, they can evade the current Large Hadron Collider (LHC) constraints.

   hep-phPRD(2021)·50 citations
5. 05*

   Cobimaximal Mixing with Dirac Neutrinos

   Ernest Ma (UC Riverside)🇺🇸

   If neutrinos are Dirac, the conditions for cobimaximal mixing, i.e. ${\theta }_{23}=\pi /4$ and ${\delta }_{CP}=\pm \pi /2$ in the $3\times 3$ neutrino mixing matrix, are derived. One example with $A_4$ symmetry and radiative Dirac neutrino masses is presented.

   hep-phPLB(2021)·6 citations
6. 06*

   Selection rules for the decay of a particle into two identical massless particles of any spin

   Seong Youl Choi🇰🇷 · Jae Hoon Jeong🇰🇷

   The well-known Landau-Yang (LY) theorem on the decay of a neutral particle into two photons is generalized for analyzing the decay of a neutral or charged particle into two identical massless particles of any spin. Selection rules categorized by discrete parity invariance and Bose/Fermi symmetry are worked out in the helicity formulation. The general form of the Lorentz-covariant triple vertices are derived and the corresponding decay helicity amplitudes are explicitly calculated in the Jacob-Wick convention. After checking the consistency of all the analytic results obtained by two complementary approaches, we extract out the key aspects of the generalized LY theorem.

   hep-phhep-thPRD(2021)·9 citations
7. 07*

   Semi-automated BSM model building procedures in MARTY-1.1 through a 2HDM example

   G. Uhlrich🇫🇷 · F. Mahmoudi🇫🇷 · A. Arbey🇫🇷

   MARTY is a C++ computer algebra system specialized for High Energy Physics that can calculate amplitudes, squared amplitudes and Wilson coefficients in a large variety of beyond the Standard Model scenarios up to the one-loop order. It is fully independent of any other framework and its main development guideline is generality, in order to be adapted easily to any type of model. The calculations are fully automated from the Lagrangian up to the generation of the C++ code evaluating the theoretical results (numerically, depending on the model parameters). Once a phenomenological tool chain has been set up - from a Lagrangian to observable analysis - it can be used in a model independent way leaving only model building, with MARTY, as the task to be performed by physicists. Here we present the main steps to build a general new physics model, namely gauge group, particle content, representations, replacements, rotations and symmetry breaking, using the example of a 2 Higgs Doublet Model. The sample codes that are shown for this example can be easily generalized to any Beyond the Standard Model scenario written with MARTY.

   hep-phPoS(2021)·4 citations
8. 08*

   A model for NL and SL decays by ${\overline{B}}^0\to D^{\ast \ast }$ transitions with $BR(j=1/2)\ll BR(j=3/2)$ using the $LLSW$ scheme

   Alain Le Yaouanc🇫🇷 · Jean-Pierre Leroy🇫🇷 · Patrick Roudeau🇫🇷

   We present a model for the vector and axial form factors of the transitions ${\overline{B}}^0\to D^{\ast \ast }$ in good agreement with the presently available data and based on the present theoretical knowledge, combining a) the safe lattice QCD predictions at $m_Q=\infty$ and $w=1$ ; b) the predictions at general $w$ of a relativistic, covariant quark model at $m_Q=\infty$, including the well tested Godfrey and Isgur spectroscopic model and which agrees with lattice QCD at $w=1$ ; c) the constraint of Bjorken and Neubert relating Semi-leptonic (SL) and Class I Non-leptonic (NL) decays, which shows that ${\overline{B}}^0\to D_0(2300{)}^{+}{\pi }^{-}$ strongly constrains ${\tau }_{1/2}(w)$ to be much smaller than ${\tau }_{3/2}(w)$, in agreement with the theoretical expectation; d) the general HQET expansion which constrains the $1/m_Q$ corrections (cf \cite{LLSW}, denoted hereafter as $LLSW$). An important element in the understanding of data is the large contribution of virtual $D_V^{(\ast )}$ to the broad structures seen in SL decays at low $D^{(\ast )}\pi$ masses - which makes it difficult to isolate the broad resonances denoted as $D_{1/2}$ in the following.

   hep-phhep-exPRD(2022)·16 citations
9. 09*

   High-precision determination of the electric and magnetic radius of the proton

   Yong-Hui Lin🇩🇪 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪

   Using dispersion theory with an improved description of the two-pion continuum based on the precise Roy-Steiner analysis of pion-nucleon scattering, we analyze recent data from electron-proton scattering. This allows for a high-precision determination of the electric and magnetic radius of the proton, $r_E=(0.838_{-0.004}^{+0.005}{}_{-0.003}^{+0.004})$fm and $r_M=(0.847\pm 0.004\pm 0.004)$fm, where the first error refers to the fitting procedure using bootstrap and the data while the second one refers to the systematic uncertainty related to the underlying spectral functions.

   hep-phhep-exhep-latnucl-ex+1PLB(2021)·49 citations
10. 10*

    Limit on Higgs boson trilinear self-coupling in coupled technicolor models

    A. Doff🇧🇷 · A. A. Natale🇧🇷

    The trilinear self-coupling of the Higgs boson, in a theory in which this boson is composite, is compared to the experimental bound of this quantity obtained by the CMS experiment. In the case of a model where technicolor (TC) is coupled to QCD, we find that the experimental result already constrain the dynamics of the theory, which is represented by an expression of the technifermion self-energy (${\Sigma }_{tc}$) typical of technicolor coupled models, and function of the dynamically generated technifermion mass and two other parameters that describe the technifermion dynamical mass momentum dependence. The limits imposed on this dynamics allow us to make a simple determination of pseudo-Goldstone boson masses that appear in these theories, indicating that these bosons may be expected to be quite massive.

    hep-phEPL(2021)·2 citations
11. 11*

    Phenomenological study of the anisotropic quark matter in the 2-flavor Nambu-Jona-Lasinio model

    He-Xia Zhang🇨🇳 · Yu-Xin Xiao🇨🇳 · Jin-Wen Kang🇨🇳 · Ben-Wei Zhang🇨🇳

    With the two flavor Nambu-Jona-Lasinio (NJL) model we carry out a phenomenological study on the chiral phase structure, mesonic properties and transport properties in a momentum-space anisotropic quark matter. To calculate transport coefficients we have utilized the kinetic theory in the relaxation time approximation, where the momentum anisotropy is embedded in the estimation of both distribution function and the relaxation time. It is shown that an increase of the anisotropy parameter $\xi$ may results in a catalysis of chiral symmetry breaking. The critical endpoint (CEP) is shifted to smaller temperatures and larger quark chemical potentials as $\xi$ increases, the impact of momentum anisotropy on temperature of CEP is almost the same as that on the quark chemical potential of CEP. The meson masses and the associated decay widths also exhibit a significant $\xi$ dependence. It is observed that the temperature behavior of scaled shear viscosity $\eta /T^3$ and scaled electrical conductivity ${\sigma }_{el}/T$ exhibit a similar dip structure, with the minima of both $\eta /T^3$ and ${\sigma }_{el}/T$ shifting toward higher temperatures with increasing $\xi$. Furthermore, we demonstrate that the Seebeck coefficient $S$ decreases when temperature goes up and its sign is positive, indicating the dominant carriers for converting the temperature gradient to the electric field are up-quarks. The Seebeck coefficient $S$ is significantly enhanced with a large $\xi$ for the temperature below the critical temperature.

    hep-phnucl-thNucl.Sci.Tech.(2022)·19 citations
12. 12*

    Ultralight Axions Versus Primordial Black Holes

    Claudio Corianò🇮🇹 · PaulH. Frampton🇮🇹 · Jihn E. Kim🇰🇷

    We reconsider entropy arguments which have been previously argued to support the idea that the dark matter constituents are primordial black holes with many solar masses. It has recently been shown that QCD axions which solve the strong CP problem may have masses $m_a$ in the extended range $10^{-3}eV>m_a>10^{-33}eV$. Ultralight axions provide so many degrees of freedom that their entropy can exceed that of primordial black holes. This suggests that ultralight axions are more suited than primordial black holes to be constituents of dark matter.

    hep-phhep-thMod.Phys.Lett.A(2021)·5 citations
13. 13*

    Exact solutions in radiation reaction and the radiation-free direction

    Robin Ekman🇬🇧 · Tom Heinzl🇬🇧 · Anton Ilderton🇬🇧

    We present new exact solutions of the Landau-Lifshitz and higher-order Landau-Lifshitz equations describing particle motion, with radiation reaction, in intense electromagnetic fields. Through these solutions and others we compare the phenomenological predictions of different equations in the context of the conjectured `radiation-free direction' (RFD). We confirm analytically in several cases that particle orbits predicted by the Landau-Lifshitz equation indeed approach the RFD at extreme intensities, and give time-resolved signals of this behaviour in radiation spectra.

    hep-phphysics.plasm-phNew J.Phys.(2021)·17 citations
14. 14*

    Testing Bell inequalities at the LHC with top-quark pairs

    M. Fabbrichesi🇮🇹 · R. Floreanini🇮🇹 · G. Panizzo🇮🇹

    Entanglement between the spins of top-quark pairs produced at a collider can be used to test a (generalized) Bell inequality at energies never explored so far. We show how the measurement of a single observable can provide a test of the violation of the Bell inequality at the 98% CL with the data already collected at the Large Hadron Collider and at the 99.99% CL with the higher luminosity of the next run.

    hep-phhep-exquant-phPRL(2021)·192 citations
15. 15*

    Neutron Interferometry and axion like particles

    Antonio Capolupo🇮🇹 · Salvatore Marco Giampaolo🇭🇷 · Aniello Quaranta🇮🇹

    We propose a method to reveal axions and axion-like particles based on interferometric measurement of neutron beams. We consider an interferometer in which the neutron beam is split in two sub-beams propagating in regions with differently oriented magnetic fields. The beam paths and the strength of the magnetic fields are set in such a way that all the contributions to the phase difference but the one due to axion-induced interactions are removed. The resulting phase difference is directly related to the presence of axions. Our results show that such a phase is in principle detectable with neutron interferometry, possibly proving the existence of axions and axion-like particles.

    hep-phhep-thEPJC(2021)·24 citations
16. 16*

    On the radiation of an arbitrary moving constant magnetic moment

    B. A. Zon (1)🇷🇺 · V. E. Chernov (1)🇷🇺 · M. Ya. Amusia (2,3) ((1) Voronezh State University, Voronezh, Russia, (2) A. F. Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Saint Petersburg, Russia (3) G. Racah Institute of Physics of the Hebrew University, Jerusalem, Israel)🇷🇺

    It is demonstrated that a constant magnetic moment does not emit electo-magnetic radiation while moving in an arbitrary field

    hep-phphysics.atom-phphysics.class-phRuss.Phys.J.(2021)·0 citations
17. 17*

    Determining the jet transport coefficient $\hat{q}$ from inclusive hadron suppression measurements using Bayesian parameter estimation

    S. Cao🇺🇸 · Y. Chen🇺🇸 · J. Coleman🇺🇸 · J. Mulligan🇺🇸 · P. M. Jacobs🇺🇸 · R. A. Soltz🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. A. Bass🇺🇸 · L. Cunqueiro🇺🇸 · T. Dai🇺🇸 · L. Du🇺🇸 and 35 other authors

    We report a new determination of $\hat{q}$, the jet transport coefficient of the Quark-Gluon Plasma. We use the JETSCAPE framework, which incorporates a novel multi-stage theoretical approach to in-medium jet evolution and Bayesian inference for parameter extraction. The calculations, based on the MATTER and LBT jet quenching models, are compared to experimental measurements of inclusive hadron suppression in Au+Au collisions at RHIC and Pb+Pb collisions at the LHC. The correlation of experimental systematic uncertainties is accounted for in the parameter extraction. The functional dependence of $\hat{q}$ on jet energy or virtuality and medium temperature is based on a perturbative picture of in-medium scattering, with components reflecting the different regimes of applicability of MATTER and LBT. In the multi-stage approach, the switch between MATTER and LBT is governed by a virtuality scale $Q_0$. Comparison of the posterior model predictions to the RHIC and LHC hadron suppression data shows reasonable agreement, with moderate tension in limited regions of phase space. The distribution of $\hat{q}/T^3$ extracted from the posterior distributions exhibits weak dependence on jet momentum and medium temperature $T$, with 90\% Credible Region (CR) depending on the specific choice of model configuration. The choice of MATTER+LBT, with switching at virtuality $Q_0$, has 90\% CR of $2<\hat{q}/T^3<4$ for $p_{\mathrm{T}}^{\mathrm{jet}}>40$ GeV/c. The value of $Q_0$, determined here for the first time, is in the range 2.0-2.7 GeV.

    ↳ nucl-thhep-phnucl-exPRC(2021)·196 citations
18. 18*

    A new Wilson line-based action for gluodynamics

    Hiren Kakkad🇵🇱 · Piotr Kotko🇵🇱 · Anna Stasto🇺🇸

    We perform a canonical transformation of fields that brings the Yang-Mills action in the light-cone gauge to a new classical action, which does not involve any triple-gluon vertices. The lowest order vertex is the four-point MHV vertex. Higher point vertices include the MHV and $\overline{\text{MHV}}$ vertices, that reduce to the corresponding amplitudes in the on-shell limit. In general, any $n$-leg vertex has $2\le m\le n-2$ negative helicity legs. The canonical transformation of fields can be compactly expressed in terms of path-ordered exponentials of fields and their functional derivative. We apply the new action to compute several tree-level amplitudes, up to 8-point NNMHV amplitude, and find agreement with the standard methods. The absence of triple-gluon vertices results in fewer diagrams required to compute amplitudes, when compared to the CSW method and, obviously, considerably fewer than in the standard Yang-Mills action.

    ↳ hep-thhep-phJHEP(2021)·7 citations
19. 19*

    Assessing the Fornax globular cluster timing problem in different models of dark matter

    Nitsan Bar🇮🇱 · Diego Blas🇬🇧 · Kfir Blum🇮🇱 · Hyungjin Kim🇮🇱

    We investigate what the orbits of globular clusters (GCs) in the Fornax dwarf spheroidal (dSph) galaxy can teach us about dark matter (DM). This problem was recently studied for ultralight dark matter (ULDM). We consider two additional models: (i) fermionic degenerate dark matter (DDM), where Pauli blocking should be taken into account in the dynamical friction computation; and (ii) self-interacting dark matter (SIDM). We give a simple and direct Fokker-Planck derivation of dynamical friction, new in the case of DDM and reproducing previous results in the literature for ULDM and cold DM. ULDM, DDM and SIDM were considered in the past as leading to cores in dSphs, a feature that acts to suppress dynamical friction and prolong GC orbits. For DDM we derive a version of the cosmological free streaming limit that is independent of the DM production mechanism, finding that DDM cannot produce an appreciable core in Fornax without violating Ly-$\alpha$ limits. If the Ly-$\alpha$ limit is discounted for some reason, then stellar kinematics data does allow a DDM core which could prolong GC orbits. For SIDM we find that significant prolongation of GC orbits could be obtained for values of the self-interaction cross section considered in previous works. In addition to reassessing the inspiral time using updated observational data, we give a new perspective on the so-called GC timing problem, demonstrating that for a cuspy cold DM profile dynamical friction predicts a $z=0$ radial distribution for the innermost GCs that is independent of initial conditions. The observed orbits of Fornax GCs are consistent with this expectation with a mild apparent fine-tuning at the level of $\sim 25\%$.

    ↳ astro-ph.GAastro-ph.COhep-phPRD(2021)·36 citations
20. 20*

    $K_1/K^{\ast }$ enhancement as a signature of chiral symmetry restoration in heavy ion collisions

    Haesom Sung🇰🇷 · Sungtae Cho🇰🇷 · Juhee Hong🇰🇷 · Su Houng Lee🇰🇷 · Sanghoon Lim🇰🇷 · Taesoo Song🇩🇪

    Based on the fact that the mass difference between the chiral partners is an order parameter of chiral phase transition and that the chiral order parameter reduces substantially at the chemical freeze-out point in ultra-relativistic heavy ion collisions, we argue that the production ratio of $K_1$ over $K^{\ast }$ in such collisions should be substantially larger than that predicted in the statistical hadronization model. We further show that while the enhancement effect might be contaminated by the relatively larger decrease of $K_1$ meson than $K^{\ast }$ meson during the hadronic phase, the signal will be visible through a systematic study on centrality as the kinetic freeze-out temperature is higher and the hadronic life time shorter in peripheral collisions than in central collisions.

    ↳ nucl-thhep-phnucl-exPLB(2021)·13 citations
21. 21*

    Anomalous Hall instability in the Chern-Simons magnetohydrodynamics

    M. Kiamari🇮🇷 · M. Rahbardar🇮🇷 · M. Shokri🇮🇷 · N. Sadooghi🇮🇷

    The Chern-Simons magnetohydrodynamics (CSMHD) is introduced using a Maxwell-Chern-Simons (MCS) Lagrangian including an axion-like field $\Theta$. The MCS equation of motion derived from this Lagrangian consists of a modified current, including a chiral magnetic (CM) and an anomalous Hall (AH) current, in addition to the ordinary Ohm current of resistive magnetohydrodynamics (MHD). The former consists of an axial chemical potential, which is given in terms of the temporal comoving derivative of $\Theta$, and the latter arises from the spatial gradient of $\Theta$. As it turns out, the existence of the axial chemical potential is a nonequilibrium effect that plays no role in the linear stability analysis, whereas the AH current arises as in the first-order linear perturbation of the thermal equilibrium. We analyze the linear stability and causality of the CSMHD in a resistive and chiral medium. We show that the Alfven modes propagating sufficiently close to the direction of the magnetic field are unstable but causal. They are also accompanied by a genuine nonhydro mode. A stable mode in a particular direction can correspond to an unstable mode propagating in the exact opposite direction. The AH instability is a manifestation of a breakdown of the parity. A numerical analysis of the phase velocity confirms these results.

    ↳ hep-thcond-mat.str-elhep-phnucl-thPRD(2021)·6 citations
22. 22*

    Projected sensitivities of the LUX-ZEPLIN (LZ) experiment to new physics via low-energy electron recoils

    The LZ Collaboration · D.S. Akerib · A.K. Al Musalhi · S.K. Alsum · C.S. Amarasinghe · A. Ames · T.J. Anderson · N. Angelides · H.M. Araújo · J.E. Armstrong · M. Arthurs · X. Bai and 185 other authors

    LUX-ZEPLIN (LZ) is a dark matter detector expected to obtain world-leading sensitivity to weakly interacting massive particles (WIMPs) interacting via nuclear recoils with a ~7-tonne xenon target mass. This manuscript presents sensitivity projections to several low-energy signals of the complementary electron recoil signal type: 1) an effective neutrino magnetic moment and 2) an effective neutrino millicharge, both for pp-chain solar neutrinos, 3) an axion flux generated by the Sun, 4) axion-like particles forming the galactic dark matter, 5) hidden photons, 6) mirror dark matter, and 7) leptophilic dark matter. World-leading sensitivities are expected in each case, a result of the large 5.6t 1000d exposure and low expected rate of electron recoil backgrounds in the $<$100keV energy regime. A consistent signal generation, background model and profile-likelihood analysis framework is used throughout.

    ↳ hep-exastro-ph.COhep-phPRD(2021)·64 citations
23. 23*

    Bjorken flow attractors with transverse dynamics

    Victor E. Ambrus🇷🇴 · Sergiu Busuioc🇬🇧 · Jan A. Fotakis🇩🇪 · Kai Gallmeister🇩🇪 · Carsten Greiner🇩🇪

    In the context of the longitudinally boost-invariant Bjorken flow with transverse expansion, we use three different numerical methods to analyze the emergence of attractor solutions in an ideal gas of massless particles exhibiting constant shear viscosity to entropy density ratio $\eta /s$. The fluid energy density is initialized using a Gaussian profile in the transverse plane, while the ratio $\chi ={\mathcal{P}}_L/{\mathcal{P}}_T$ between the longitudinal and transverse pressures is set at initial time ${\tau }_0$ to a constant value ${\chi }_0$ throughout the system employing the Romatschke-Strickland distribution. We introduce the hydrodynamization time $\delta {\tau }_H=({\tau }_H-{\tau }_0)/{\tau }_0$ based on the time ${\tau }_H$ when the standard deviation $\sigma (\chi )$ of a family of solutions with different ${\chi }_0$ reaches a minimum value at the point of maximum convergence of the solutions. In the $0+1\mathrm{D}$ setup, $\delta {\tau }_H$ exhibits scale invariance, being a function only of $(\eta /s)/({\tau }_0{T}_0)$. With transverse expansion, we find a similar $\delta {\tau }_H$ computed with respect to the local initial temperature, $T_0(r)$. We highlight the transition between the regimes where the longitudinal and transverse expansions dominate. We find that the hydrodynamization time required for the attractor solution to be reached increases with the distance from the origin, as expected based on the properties of the $0+1\mathrm{D}$ system defined by the local initial conditions. We argue that hydrodynamization is predominantly the effect of the longitudinal expansion, being significantly influenced by the transverse dynamics only for small systems or for large values of $\eta /s$.

    ↳ nucl-thhep-phphysics.flu-dynPRD(2021)·34 citations
24. 24*

    Revealing the structure of light pseudoscalar mesons at the Electron-Ion Collider

    John Arrington🇺🇸 · Carlos Ayerbe Gayoso🇺🇸 · Patrick C Barry🇺🇸 · Vladimir Berdnikov🇺🇸 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Markus Diefenthaler🇺🇸 · Minghui Ding🇮🇹 · Rolf Ent🇺🇸 · Tobias Frederico🇧🇷 · Yulia Furletova🇺🇸 · Tim J Hobbs🇺🇸 and 20 other authors

    How the bulk of the Universe's visible mass emerges and how it is manifest in the existence and properties of hadrons are profound questions that probe into the heart of strongly interacting matter. Paradoxically, the lightest pseudoscalar mesons appear to be the key to the further understanding of the emergent mass and structure mechanisms. These mesons, namely the pion and kaon, are the Nambu-Goldstone boson modes of QCD. Unravelling their partonic structure and the interplay between emergent and Higgs-boson mass mechanisms is a common goal of three interdependent approaches -- continuum QCD phenomenology, lattice-regularised QCD, and the global analysis of parton distributions -- linked to experimental measurements of hadron structure. Experimentally, the foreseen electron-ion collider will enable a revolution in our ability to study pion and kaon structure, accessed by scattering from the "meson cloud" of the proton through the Sullivan process. With the goal of enabling a suite of measurements that can address these questions, we examine key reactions to identify the critical detector system requirements needed to map tagged pion and kaon cross sections over a wide range of kinematics. The excellent prospects for extracting pion structure function and form factor data are shown, and similar prospects for kaon structure are discussed in the context of a worldwide programme. Successful completion of the programme outlined herein will deliver deep, far-reaching insights into the emergence of pions and kaons, their properties, and their role as QCD's Goldstone boson modes.

    ↳ nucl-exhep-phnucl-thJ.Phys.G(2021)·135 citations
25. 25*

    Beam-normal single-spin asymmetry in elastic scattering of electrons from a spin-0 nucleus

    Oleksandr Koshchii🇩🇪 · Mikhail Gorchtein🇩🇪 · Xavier Roca-Maza🇮🇹 · Hubert Spiesberger🇩🇪

    We study the beam-normal single-spin asymmetry (BNSSA) in high-energy elastic electron scattering from several spin-0 nuclei. Existing theoretical approaches work in the plane-wave formalism and predict the BNSSA to scale as $\sim A/Z$ with the atomic number $Z$ and nuclear mass number $A$. While this prediction holds for light and intermediate nuclei, a striking disagreement in both the sign and the magnitude of BNSSA was observed by the PREX collaboration for ${}^{208}$Pb, coined the "PREX puzzle". To shed light on this disagreement, we go beyond the plane-wave approach which neglects Coulomb distortions known to be significant for heavy nuclei. We explicitly investigate the dependence of BNSSA on $A$ and $Z$ by i) including inelastic intermediate states' contributions into the Coulomb problem in the form of an optical potential, ii) by accounting for the experimental information on the $A$-dependence of the Compton slope parameter, and iii) giving a thorough account of the uncertainties of the calculation. Despite of these improvements, the PREX puzzle remains unexplained. We discuss further strategies to resolve this riddle.

    ↳ nucl-thhep-phnucl-exPRC(2021)·15 citations
26. 26*

    Neutrinos from tidal disruption events

    Kimitake Hayasaki🇰🇷

    Tidal disruption events are an excellent probe for supermassive black holes in distant inactive galaxies because they show bright multi-wavelength flares lasting several months to years. AT2019dsg presents the first potential association with neutrino emission from such an explosive event.

    ↳ astro-ph.HEastro-ph.GAhep-exhep-phNat Astron (2021)·28 citations
27. 27*

    Horizons and the Wave Function of Planckian Quantum black holes

    Euro Spallucci🇮🇹 · Anais Smailagic🇮🇹

    At the Planck scale the distinction between elementary particles and black holes becomes fuzzy. The very definition of a "quantum black hole" (QBH) is an open issue. Starting from the idea that, at the Planck scale, the radius of the event horizon undergoes quantum oscillations, we introduce a black hole mass-radius Generalised Uncertainty Principle (GUP) and derive a corresponding gravitational wavelength. Next we recover a GUP encoding effective geometry. This semi-classical gravitational description admits black hole configurations only for masses higher than the Planck mass. Quantum corrections lead to a vanishing Hawking temperature when the Planck mass is approached from above. Finally we replace our semi-classical model by a relativistic wave equation for the "horizon wave function". The solution admits a discrete mass spectrum which is bounded from below by a stable ground state with energy close to the Planck mass. Interestingly higher angular momentum states fit onto Regge trajectories indicating their stringy nature.

    ↳ hep-thgr-qchep-phPLB(2021)·14 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.