Tue·Nov 16, 2021Tuesday·November 16, 2021

1. 01*

   Charged-averaged elastic lepton-proton scattering cross section results from OLYMPUS

   Axel Schmidt🇺🇸

   Measurements of the proton's form factor ratio made with polarization transfer show a striking discrepancy relative to the ratio extracted from unpolarized elastic electron-proton scattering cross sections. One hypothesis is that the discrepancy is caused by hard two-photon exchange (TPE), a typically neglected radiative correction that may bias the two approaches differently. This hypothesis has been challenging to confirm. Theoretical estimates of TPE are model-dependent, and recent experimental determinations of TPE lacked the kinematic reach to be conclusive. The possible impact of TPE remains a cloud over our knowledge of the proton's form factors. Recently, the OLYMPUS experiment published new elastic scattering cross sections that are insensitive to the effects of TPE: specifically the average of electron-proton and positron-proton cross sections. The OLYMPUS experiment, conducted at DESY, Hamburg, measured elastic $e^{-}p$ and $e^{+}p$ scattering by detecting the scattered lepton and recoiling proton in coincidence in a large-acceptance, toroidal magnetic spectrometer. OLYMPUS was designed to measure the $e^{+}p/e^{-}p$ cross section raio to isolate the effects of TPE. By exploiting the over determined kinematics of the reaction, the absolute efficiency of spectrometer could be verified, allowing cross sections to be extracted from the data. These results can help refine our knowledge of the proton's form factors, especially in the squared momentum-transfer region of 1--2 GeV${}^2$, where some previous measurements are in tension.

   nucl-exPoS(2022)·0 citations
2. 02*

   Systematic study of {\Delta}(1232) resonance excitations using single isobaric charge-exchange reactions induced by medium-mass projectiles of Sn

   J. L. Rodriguez-Sanchez🇪🇸 · J. Benlliure🇪🇸 · I. Vidana🇮🇹 · H. Lenske🇩🇪 · J. Vargas🇪🇸 · C. Scheidenberger🇩🇪 · H. Alvarez-Pol🇪🇸 · J. Atkinson🇩🇪 · T. Aumann🇩🇪 · Y. Ayyad🇪🇸 · S. Beceiro-Novo🇪🇸 · K. Boretzky🇩🇪 and 17 other authors

   The fragment separator FRS has been for the first time used to measure the (n,p) and (p,n)-type isobaric charge-exchange cross sections of stable 112,124Sn isotopes accelerated at 1A GeV with an uncertainty of 3% and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic contribution can be associated to the excitation of isobar {\Delta}(1232) resonances and to the pion emission in s-wave, both in the target and projectile nuclei, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. The data lead to interesting results where we observe a clear quenching of the quasi-elastic component and their comparisons to theoretical calculations demonstrate that the baryonic resonances can be excited in the target and projectile nuclei. To go further in this investigation, we propose to study the excitation of baryonic resonances taking advantage of the combination of high-resolving power magnetic spectrometers with the WASA calorimeter. These new measurements will allow us to determine the momenta of the ejectiles and pions emitted in coincidence after the single isobaric charge-exchange collisions, providing us unique opportunities to study the evolution of the baryonic resonance dynamics with the neutron-proton asymmetry through the use of exotic radioactive ion beams.

   nucl-exnucl-thPRC(2022)·10 citations
3. 03*

   Enhanced production of ${}^8$Be nuclei in relativistic nuclei fragmentation

   N.G. Peresadko · A.A. Zaitsev🇷🇺 · P.I. Zarubin🇷🇺

   This article is dedicated to the results of early measuring fragmentation of relativistic ${}^{16}$O, ${}^{22}$Ne, ${}^{28}$Si, and ${}^{197}$Au nuclei in a nuclear track emulsion. It has been found that there is a contribution of the unstable ${}^8$Be nucleus decays to $\alpha$-particle multiplicities. These renewed measurements of nuclear track emulsion exposed to ${}^{84}$Kr nuclei at the energy of 950 MeV per nucleon have been analyzed and given below.

   nucl-exPoS(2022)·1 citation
4. 04*

   COHERENT at the Spallation Neutron Source

   P.S. Barbeau🇺🇸 · Yu. Efremenko🇺🇸 · K. Scholberg🇺🇸

   The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory provides an intense, high-quality source of neutrinos from pion decay at rest. This source was recently used for the first measurements of coherent elastic neutrino-nucleus scattering (CEvNS) by the COHERENT collaboration, resulting in new constraints of beyond-the-standard-model physics. The SNS neutrino source will enable further CEvNS measurements, exploration of inelastic neutrino-nucleus interactions of particular relevance for understanding of supernova neutrinos, and searches for accelerator-produced sub-GeV dark matter. Taking advantage of this unique facility, COHERENT's suite of detectors in "Neutrino Alley'' at the SNS is accumulating more data to address a broad physics program at the intersection of particle physics, nuclear physics, and astrophysics. This review describes COHERENT's first two CEvNS measurements, their interpretation, and the potential of a future physics program at the SNS.

   ↳ hep-exastro-ph.IMnucl-exAnn.Rev.Nucl.Part.Sci.(2023)·40 citations
5. 05*

   Near Threshold Heavy Quarkonium Photoproduction at Large Momentum Transfer

   Peng Sun🇨🇳 · Xuan-Bo Tong🇨🇳 · Feng Yuan🇺🇸

   Perturbative QCD is applied to investigate the near threshold heavy quarkonium photoproduction at large momentum transfer. We take into account the contributions from the leading three-quark Fock states of the nucleon. The dominant contribution comes from the three-quark Fock state with one unit quark orbital angular momentum (OAM) whereas that from zero quark OAM is suppressed at the threshold. From our analysis, we also show that there is no direct connection between the near threshold heavy quarkonium photoproduction and the gluonic gravitational form factors of the nucleon. Based on the comparison between our result and recent GlueX data of $J/\psi$ photoproduction, we make predictions for ${\psi }^{\prime }$ and ${\rm Y}$ (1S,2S) states which can be tested in future experiments.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2022)·44 citations
6. 06*

   Isoscalar giant monopole resonance in ${}^{24}$Mg and ${}^{28}$Si: Effect of coupling between the isoscalar monopole and quadrupole strength

   A. Bahini (1 and 2) · V. O. Nesterenko (3, 4 and 5) · I. T. Usman (1) P. von Neumann-Cosel (6) · R. Neveling (2) · J. Carter (1) · J. Kvasil (7) · A. Repko (7 and 8) · P. Adsley (1, 2, 9 and 10) · N. Botha (1) · J. W. Brummer (2, 9) · L. M. Donaldson (2) · S. Jongile (2 and 9) and 14 other authors

   Background: In highly deformed nuclei, there is a noticeable coupling of the Isoscalar Giant Monopole Resonance (ISGMR) and the $K=0$ component of the Isoscalar Giant Quadrupole Resonance (ISGQR), which results in a double peak structure of the isoscalar monopole (IS0) strength (a narrow low-energy deformation-induced peak and a main broad ISGMR part). The energy of the narrow low-lying IS0 peak is sensitive to both the incompressibility modulus $K_{\infty }$ and the coupling between IS0 and isoscalar quadrupole (IS2) strength. Objective: This study aims to investigate the two-peaked structure of the ISGMR in the prolate ${}^{24}$Mg and oblate ${}^{28}$Si nuclei and identify among a variety of energy density functionals based on Skyrme parameterisations the one which best describes the experimental data. This will allow for conclusions regarding the nuclear incompressibility. Because of the strong IS0/IS2 coupling, the deformation splitting of the ISGQR will also be analysed. Methods: The ISGMR was excited in ${}^{24}$Mg and ${}^{28}$Si using $\alpha$-particle inelastic scattering measurements acquired with an $E_{\alpha }=196$ MeV beam at scattering angles ${\theta }_{\text{Lab}}=0^{\circ }$ and $4^{\circ }$. The K$600$ magnetic spectrometer at iThemba LABS was used to detect and momentum analyse the inelastically scattered $\alpha$ particles. An experimental energy resolution of $\approx 70$ keV (FWHM) was attained, revealing fine structure in the excitation-energy region of the ISGMR. The IS0 strength distributions in the nuclei studied were obtained with the Difference-of-Spectrum (DoS) technique. The theoretical comparison is based on the quasiparticle random-phase approximation (QRPA) with a representative set of Skyrme forces.

   ↳ nucl-thnucl-exPRC(2022)·17 citations
7. 07*

   Model study of the energy dependence of the correlation between anisotropic flow and the mean transverse momentum in Au+Au collisions

   Niseem Magdy🇺🇸 · Petr Parfenov🇷🇺 · Arkadiy Taranenko🇷🇺 · Iurii Karpenko🇨🇿 · Roy A. Lacey🇺🇸

   A hybrid model that employs the hadron-string transport model UrQMD and the (3+1)D relativistic viscous hydrodynamic code vHLLE, is used to investigate the beam energy dependence of the correlation coefficient $\rho (v_2^2,[p_T])$ between the average transverse momentum $[p_T]$ of hadrons emitted in an event and the square of the anisotropic flow coefficient $v_2^2$. For Au+Au collisions, the model predicts characteristic patterns for the energy and event-shape dependence of the variances for $[p_T]$ and $v_n^2$ ($\mathrm{Var}([p_T])$ and $\mathrm{Var}(v_2^2)$), and the covariance of $v_n^2$ and $[p_T]$ ($\mathrm{cov}(v_2^2,[p_T])$), consistent with the attenuation effects of the specific shear viscosity $\eta /s$. In contrast, $\rho (v_2^2,[p_T])$ is predicted to be insensitive to the beam energy but sensitive to the initial-state geometry of the collisions. These observations suggest that a precise set of measurements for $\mathrm{Var}([p_T])$, $\mathrm{Var}(v_2^2)$, $\mathrm{cov}(v_2^2,[p_T])$ and $\rho (v_2^2,[p_T])$ as a function of beam-energy and event-shape, could aid precision extraction of the temperature and baryon chemical-potential dependence of $\eta /s$ from the wealth of Au+Au data obtained in the RHIC beam energy scan.

   ↳ nucl-thhep-phnucl-exPRC(2022)·8 citations
8. 08*

   $\alpha$ knockout reaction as a new probe for $\alpha$ formation in $\alpha$-decay nuclei

   Kazuki Yoshida🇯🇵 · Junki Tanaka

   The $\alpha$-decay phenomennon has been studied for more than a century but the mechanism of the $\alpha$ particle formation and its tunneling process have not yet been fully understood. As an alternative to the $\alpha$-decay lifetime measurement, we propose the proton-induced $\alpha$ knockout reaction, ($p$,$p\alpha$), as a new probe for the surface $\alpha$ formation probability of $\alpha$-decay nuclei. The ${}^{210,212}$Po($p$,$p\alpha$)${}^{206,208}$Pb reaction is described by the distorted-wave impulse approximation framework. It shows that the ${}^{212}$Po/${}^{210}$Po ratio of the $\alpha$ knockout cross sections agrees with that of the surface $\alpha$ formation probabilities determined by lifetime measurements. The result implies that the ($p$,$p\alpha$) cross section is a direct probe for the surface $\alpha$ formation probability, which is an essential quantity to lead us to a complete understanding of the $\alpha$-decay phenomenon.

   ↳ nucl-thnucl-exPRC(2022)·14 citations
9. 09*

   Status and Perspectives of Neutrino Physics

   M. Sajjad Athar🇮🇳 · Steven W. Barwick🇺🇸 · Thomas Brunner🇨🇦 · Jun Cao🇨🇳 · Mikhail Danilov🇷🇺 · Kunio Inoue🇯🇵 · Takaaki Kajita🇯🇵 · Marek Kowalski🇩🇪 · Manfred Lindner🇩🇪 · Kenneth R. Long🇬🇧 · Nathalie Palanque-Delabrouille🇫🇷 · Werner Rodejohann🇩🇪 and 7 other authors

   This review demonstrates the unique role of the neutrino by discussing in detail the physics of and with neutrinos. We deal with neutrino sources, neutrino oscillations, absolute masses, interactions, the possible existence of sterile neutrinos, and theoretical implications. In addition, synergies of neutrino physics with other research fields are found, and requirements to continue successful neutrino physics in the future, in terms of technological developments and adequate infrastructures, are stressed.

   ↳ hep-phastro-ph.IMhep-exnucl-exPPNP(2022)·136 citations
10. 10*

    Microscopic study of higher-order deformation effects on the ground states of superheavy nuclei around ${}^{270}$Hs

    Xiao-Qian Wang · Xiang-Xiang Sun🇨🇳 · Shan-Gui Zhou🇨🇳

    We study the effects of higher-order deformations ${\beta }_{\lambda }$ ($\lambda =4,6,8,$ and $10$) on the ground state properties of superheavy nuclei (SHN) near the doubly magic deformed nucleus ${}^{270}$Hs by using the multidimensionally-constrained (MDC) relativistic mean-field (RMF) model with five effective interactions PC-PK1, PK1, NL3${}^{\ast }$, DD-ME2, and PKDD. The doubly magic properties of ${}^{270}$Hs are featured by the large energy gaps at $N=162$ and $Z=108$ in the single-particle spectra. By investigating the binding energies and single-particle levels of ${}^{270}$Hs in multidimensional deformation space, we find that the deformation ${\beta }_6$ has the greatest impact on the binding energy among these higher-order deformations and influences the shell gaps considerably. Similar conclusions hold for other SHN near ${}^{270}$Hs. Our calculations demonstrate that the deformation ${\beta }_6$ must be considered when studying SHN by using MDC-RMF.

    ↳ nucl-thnucl-exCPC(2022)·22 citations
11. 11*

    Accurate relativistic chiral nucleon-nucleon interaction up to NNLO

    Jun-Xu Lu🇨🇳 · Chun-Xuan Wang🇨🇳 · Yang Xiao🇨🇳 · Li-Sheng Geng🇨🇳 · Jie Meng🇨🇳 · Peter Ring🇩🇪

    We construct a relativistic chiral nucleon-nucleon interaction up to the next-to-next-to-leading order in covariant baryon chiral perturbation theory. We show that a good description of the $np$ phase shifts up to $T_{\mathrm{lab}}=200$ MeV and even higher can be achieved with a ${\tilde{\chi }}^2/d.o.f.$ less than 1. Both the next-to-leading order results and the next-to-next-to-leading order results describe the phase shifts equally well up to $T_{\mathrm{lab}}=200$ MeV, but for higher energies, the latter behaves better, showing satisfactory convergence. The relativistic chiral potential provides the most essential inputs for relativistic ab initio studies of nuclear structure and reactions, which has been in need for almost two decades.

    ↳ nucl-thhep-lathep-phnucl-exPRL(2022)·69 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.