Fri·Aug 15, 2025Friday·August 15, 2025

1. 01*

   Measurement of Beam-Recoil Observables $C_x$ and $C_z$ for $K^{+}\Lambda$ Photoproduction

   CLAS Collaboration: S. Adhikari · B. A. Raue · D. S. Carman · L. Guo · T. Chetry · P. Achenbach · J. S. Alvarado · M. J. Amaryan · W. R. Armstrong · H. Atac · H. Avakian · L. Baashen and 144 other authors

   Exclusive photoproduction of $K^{+}\Lambda$ final states off a proton target has been an important component in the search for missing nucleon resonances and our understanding of the production of final states containing strange quarks. Polarization observables have been instrumental in this effort. The current work is an extension of previously published CLAS results on the beam-recoil transferred polarization observables $C_x$ and $C_z$. We extend the kinematic range up to invariant mass $W=3.33$~GeV from the previous limit of $W=2.5$~GeV with significantly improved statistical precision in the region of overlap. These data will provide for tighter constraints on the reaction models used to unravel the spectrum of nucleon resonances and their properties by not only improving the statistical precision of the data within the resonance region, but also by constraining $t$-channel processes that dominate at higher $W$ but extend into the resonance region.

   nucl-exPRC(2025)·1 citation
2. 02*

   Triaxial relativistic Hartree-Bogoliubov theory in continuum for exotic nuclei

   Kaiyuan Zhang🇩🇪 · Shuangquan Zhang🇨🇳 · Jie Meng🇨🇳

   A triaxial relativistic Hartree-Bogoliubov theory in continuum (TRHBc) has been developed to incorporate triaxial deformation, pairing correlations, and continuum effects in a fully microscopic and self-consistent way, aiming for a reliable description of triaxial exotic nuclei with extreme neutron-to-proton ratios. The TRHBc formalism is presented in detail, and its numerical implementation is benchmarked against the results from the axially deformed relativistic Hartree-Bogoliubov theory in continuum and the TRHB theory in harmonic oscillator expansion. The TRHBc theory is applied to investigate the aluminum isotopes systematically, and the available data are well reproduced for the binding energies, one- and two-neutron separation energies, and charge radii. The nuclei near the one-neutron drip line, ${}^{40}$Al and ${}^{42}$Al, are found to be triaxially deformed with one-neutron separation energies below 1 MeV. Possible neutron halos in the triaxial nuclei ${}^{40}$Al and ${}^{42}$Al are explored by examining the single-particle levels around the Fermi surface, including their composition and contribution to the total neutron density. The existence of neutron halos in ${}^{40}$Al and ${}^{42}$Al is also supported by the halo scale, which is comparable to other halo nuclei well-established previously. More importantly, the mechanism for the halo formation in ${}^{40}$Al is revealed to be the triaxial deformation, which results in the decoupling of the halo orbitals from those of the core.

   ↳ nucl-thnucl-exPRC(2025)·11 citations
3. 03*

   Ab initio computations of the fourth-order charge density moments of ${}^{48}$Ca and ${}^{208}$Pb

   T. Miyagi🇩🇪 · M. Heinz🇺🇸 · A. Schwenk🇩🇪

   Neutron skins of neutron-rich nuclei connect nuclei with the matter in neutron stars. High-precision measurements of nuclear charge densities to extract higher-order moments are proposed to be sensitive to neutron radii and skin thicknesses. We investigate the charge density of ${}^{48}$Ca and ${}^{208}$Pb, leading candidates for such studies, with ab initio nuclear structure calculations. We find strong correlations between the fourth-order charge density moment $R_{\mathrm{ch}}^4$ and the charge and neutron radii, allowing us to predict $R_{\mathrm{ch}}^4$ for ${}^{48}$Ca and ${}^{208}$Pb. We find a substantially weaker correlation between the fourth-order charge density moment and the neutron skin, limiting the ability of high-precision electron scattering to determine the neutron skin in a model-independent manner.

   ↳ nucl-thnucl-exPLB(2026)·10 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.