Wed·Jan 17, 2024Wednesday·January 17, 2024

1. 01*

   High-precision mass measurements of neutron deficient silver isotopes probe the robustness of the $N$ = 50 shell closure

   Zhuang Ge · Mikael Reponen · Tommi Eronen · Baishan Hu · Markus Kortelainen · Anu Kankainen · Iain Moore · Dmitrii Nesterenko · Cenxi Yuan · Olga Beliuskina · Laetitia Cañete · Ruben de Groote and 27 other authors

   High-precision mass measurements of exotic ${}^{95-97}$Ag isotopes close to the $N=Z$ line have been conducted with the JYFLTRAP double Penning trap mass spectrometer, with the silver ions produced using the recently commissioned inductively-heated hot cavity catcher laser ion source at the Ion Guide Isotope Separator On-Line facility. The atomic mass of ${}^{95}$Ag was directly determined for the first time. In addition, the atomic masses of $\beta$-decaying 2${}^{+}$ and 8${}^{+}$ states in ${}^{96}$Ag have been identified and measured for the first time, and the precision of the ${}^{97}$Ag mass has been improved. The newly measured masses, with a precision of $\approx$ 1 keV/c${}^2$, have been used to investigate the $N=$ 50 neutron shell closure confirming it to be robust. Empirical shell-gap and pairing energies determined with the new ground-state mass data are compared with the state-of-the-art \textit{ab initio} calculations with various chiral effective field theory Hamiltonians. The precise determination of the excitation energy of the ${}^{96m}$Ag isomer in particular serves as a benchmark for \textit{ab initio} predictions of nuclear properties beyond the ground state, specifically for odd-odd nuclei situated in proximity to the proton dripline below ${}^{100}$Sn. In addition, density functional theory (DFT) calculations and configuration-interaction shell-model (CISM) calculations are compared with the experimental results. All theoretical approaches face challenges to reproduce the trend of nuclear ground-state properties in the silver isotopic chain across the $N=$50 neutron shell and toward the proton drip-line.

   nucl-exnucl-thPRL(2024)·24 citations
2. 02*

   Constraints on the isovector properties of finite nuclei from neutron stars observations

   M. Divaris🇬🇷 · A. Kanakis-Pegios🇬🇷 · Ch.C. Moustakidis🇬🇷

   The nuclear symmetry energy plays important role on the structure of finite nuclei as well as on the bulk properties of neutron stars. However, its values at high densities are completely uncertain and the corresponding experimental data have a large error. One possibility to determine or at least estimate the values at high densities is with the help of neutron star observations. Recently, observations of gravitational waves from merging processes of binary neutron star systems provide useful information on both their radius and tidal deformability, quantities directly related to the symmetry energy. In this work, an attempt is made in this direction, namely to see how recent observations can help to constrain the structure of finite nuclei. In particular, in the present study we parameterize the equation of state which describes the asymmetric and symmetric nuclear mater with the help of the parameter $\eta =(K_0{L}^2{)}^{1/3}$, where $K_0$ is the incompressibility and $L$ the slope parameter. The parameter $\eta$ is a regulator of the stiffness of the equation of state. We expect that the values of $\eta$ affect both the properties of finite nuclei as well as of the neutron star properties (where the role of the isovector interaction plays important role). It is natural to expect that constraints, via the parameter $\eta$ on finite nuclei will imply constraints on the neutron star properties and vice versa. In view of the above statements we propose a simple but self-consistent method to examine simultaneously the effects of the parameter $\eta$ on the properties of finite nuclei and neutron stars. We found constraints on the latter systems via combination by the recent experiments (PREX-2) and observational data found by the detectors Ligo and Virgo.

   ↳ nucl-thastro-ph.HEastro-ph.SRnucl-exPRC(2024)·9 citations
3. 03*

   Probing the four-fermion operators via the transverse double spin asymmetry at the Electron-Ion Collider

   Hao-Lin Wang🇨🇳 · Xin-Kai Wen🇨🇳 · Hongxi Xing🇨🇳 · Bin Yan🇨🇳

   The chirality-flipping operators of light fermions are currently poorly constrained by experimental analyses due to the lack of interference with Standard Model (SM) amplitudes in traditional observables. In this work, we propose to investigate the semi-leptonic scalar/tensor four-fermion operators of electron and quarks through the transverse double spin asymmetry (DSA) at Electron-Ion Collider, where both the electron and proton beams could be highly transversely polarized. Due to the chirality-flipping nature of these operators, we demonstrate that their interference with the SM results in an unsuppressed contribution to the DSA, and could lead to non-trivial azimuthal $\cos 2\varphi$ and $\sin 2\varphi$ distributions that are linearly dependent on their Wilson coefficients. This new method has the potential to significantly improve the current constraints on these scalar/tensor four-fermion operators without relying on theoretical assumptions about other types of new physics effects, particularly for the tensor type operator of the $u$-quark. Additionally, our findings indicate that both the real and imaginary parts of these operators can be simultaneously constrained and offer a new opportunity for probing potential $CP$-violation effects. However, it is important to note that these results would be sensitive to the quark transversity distributions, which are currently poorly constrained by the experimental data, but could be significantly improved at the upcoming Electron-Ion Collider. Therefore, our work opens up a new avenue to utilize this new spin asymmetry for exploring the new physics effects from the scalar/tensor four-fermion operators.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2024)·23 citations
4. 04*

   Probing parton distributions in ep/eA and ultra-peripheral collisions

   Spencer R. Klein🇺🇸

   Real or virtual photons are excellent probes of nuclear structure, with a strong sensitivity to gluon distributions. Photonic reactions can be studied using ultra-peripheral collisions or at an electron-ion collider. Final states like dijets or open charm production are directly sensitive to the gluon distributions in nuclei. Exclusive reactions, like exclusive vector meson production or deeply virtual Compton scattering (DVCS) go further, requiring at least two gluons. In the Good-Walker paradigm, coherent exclusive photoproduction is sensitive to the average nuclear configuration (including gluonic hot spots), and the Fourier transform of the differential cross-section $d\sigma /dt$ gives the transverse distribution of partonic targets in a nucleus. The incoherent photoproduction cross-section is sensitive to partonic fluctuations, including gluonic hot spots. Some reactions, such as dijet production, involve multiple momentum scales, and thus may be able to probe the Wigner distribution of nuclear targets. Finally, incoherent photoproduction is sensitive to partonic fluctuations; an analysis of $J/\psi$ photoproduction on proton targets found that the data clearly preferred a fluctuating lumpy proton.

   ↳ hep-exhep-phnucl-exPoS(2024)·1 citation

* 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.