Mon·Jan 17, 2022Monday·January 17, 2022

1. 01*

   First study of the two-body scattering involving charm hadrons

   ALICE Collaboration

   This article presents the first measurement of the interaction between charm hadrons and nucleons. The two-particle momentum correlations of $\mathrm{p}{\mathrm{D}}^{-}$ and ${\overline{\mathrm{p}}\mathrm{D}}^{+}$ pairs are measured by the ALICE Collaboration in high-multiplicity pp collisions at $\sqrt{s}=13\mathrm{TeV}$. The data are compatible with the Coulomb-only interaction hypothesis within (1.1-1.5)$\sigma$. The level of agreement slightly improves if an attractive nucleon(N)$\overline{\mathrm{D}}$ strong interaction is considered, in contrast to most model predictions which suggest an overall repulsive interaction. This measurement allows for the first time an estimation of the 68% confidence level interval for the isospin $\mathrm{I}=0$ inverse scattering length of the $\mathrm{N}\overline{\mathrm{D}}$ state $f_{0,\mathrm{I}=0}^{-1}\in [-0.4,0.9]\mathrm{f}{\mathrm{m}}^{-1}$, assuming negligible interaction for the isospin $\mathrm{I}=1$ channel.

   nucl-exhep-exPRD(2022)·91 citations
2. 02*

   Multiparticle-hole excitations in nuclei near N = Z = 20: ${}^{41}$K

   E. Rubino🇺🇸 · S. L. Tabor · Vandana Tripathi🇮🇳 · R. S. Lubna🇺🇸 · B. Abromeit · J. m. Allmond🇺🇸 · L. T. Baby · D. D. Caussyn🇺🇸 · K. Kravvaris🇺🇸 · A. Volya🇺🇸

   This experimental study of high-spin structure near N = Z = 20 nuclei was focused on ${}^{41}$K, but will also mention three newly observed $\gamma$ transitions in ${}^{41}$Ca observed in the same reaction. High-spin states were populated using the ${}^{26}$Mg(${}^{18}$O, $p2n\gamma$)${}^{41}$K and ${}^{26}$Mg(${}^{18}$O, $3n\gamma$)${}^{41}$Ca reactions. The experiment was carried out at an incident beam energy of 50 MeV at the Florida State University (FSU) John D. Fox Superconducting Linear Accelerator Laboratory and used the FSU high-purity germanium detector array. The ${}^{41}$K level scheme was extended to 12325 keV, possibly with J${}^{\pi }$ = 25/2${}^{-}$ or 27/2${}^{+}$, by means of 25 new transitions and that of ${}^{41}$Ca to 9916 keV. Linear polarization and a measure of angular distribution results are also reported and used to provide information on the spins and parities of several states in the ${}^{41}$K decay scheme. The results have been compared to the $spsdpf$ cross-shell FSU shell model interaction calculations. The theoretical results from configurations involving no or one additional nucleon promoted from the $sd$ to the $fp$ shell agree relatively well with the energies of known states, while those that involve multi-particle excitations paint an interesting and complex picture of interplay between single-particle excitations, collective pairing, and deformation. This presents an interesting challenge for future theory.

   nucl-exnucl-thEPJA(2022)·1 citation
3. 03*

   Emerging concepts in nuclear structure based on the shell model

   Takaharu Otsuka🇯🇵

   Some emerging concepts of nuclear structure are overviewed. (1) Background: the many-body quantum structure of atomic nucleus, a complex system comprising protons and neutrons (called nucleons collectively), has been studied largely based on the idea of the quantum liquid (a la Landau), where nucleons are quasiparticles moving in a (mean) potential well, with weak "residual" interactions between nucleons. The potential is rigid in general, although it can be anisotropic. While this view was a good starting point, it is time to look into kaleidoscopic aspects of the nuclear structure brought in by underlying dynamics and nuclear forces. (2) Methods: exotic features as well as classical issues are investigated from fresh viewpoints based on the shell model and nucleon-nucleon interactions. The 70-year progress of the shell-model approach, including effective nucleon-nucleon interactions, enables us to do this. (3) Results: we go beyond the picture of the solid potential well by activating the monopole interactions of the nuclear forces. This produces notable consequences in key features such as the shell/magic structure, the shape deformation, the dripline, etc. These consequences are understood with emerging concepts such as shell evolution (incl. type-II), T-plot, self-organization (for collective bands), triaxial-shape dominance, new dripline mechanism, etc. The resulting predictions and analyses agree with experiment. (4) Conclusion: atomic nuclei are surprisingly richer objects than initially thought.

   ↳ nucl-thnucl-exMDPI Physics(2022)·15 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.