Wed·Apr 3, 2024Wednesday·April 3, 2024

1. 01*

   Investigation of reaction and $\alpha$ production cross sections with ${}^9$Be projectile

   Satbir Kaur🇨🇦 · V. V. Parkar · S. K. Pandit🇮🇳 · A. Shrivastava🇮🇳 · K. Mahata · K. Ramachandran🇮🇳 · Sangeeta Dhuri🇮🇳 · P. C. Rout · A. Kumar🇩🇪 · Shilpi Gupta🇮🇳

   In order to investigate the contribution of $\alpha$ production in the reaction cross sections, measurements of elastic scattering and inclusive $\alpha$ particle angular distributions have been carried out with the ${}^9$Be projectile on ${}^{89}$Y, ${}^{124}$Sn, ${}^{159}$Tb, ${}^{198}$Pt, and ${}^{209}$Bi targets over a wide angular range at energies near the Coulomb barrier. The measured elastic scattering angular distributions were fitted with optical model calculations, and reaction cross sections were extracted. The same data were also analysed using both global optical model potentials (Global OMP) and microscopic S$\tilde{a}$o Paulo potentials (SPP), to obtain the reaction cross sections. The data available in the literature for ${}^9$Be projectile includes the elastic scattering angular distributions, $\alpha$ production cross sections, and complete fusion cross sections on these and other targets at several energies are also utilised for comparative studies. The reaction cross section extracted from the three potentials (Best Fit, Global OMP and SPP) are in reasonable agreement for all the targets except for the energies below the barrier where the results from SPP deviate by 30-50 \%. Inclusive $\alpha$ particle production cross sections were also extracted by integrating the $\alpha$ particle angular distributions. The present data and data available from literature of reaction and $\alpha$-particle production cross sections were utilised to make systematic studies. Systematics of reaction and $\alpha$-particle production cross sections revealed their universal behaviour.

   nucl-exnucl-thNPA(2024)·7 citations
2. 02*

   Measurement of the mesonic decay branch of the $\bar{K}NN$ quasi-bound state

   T. Yamaga🇯🇵 · S. Ajimura🇯🇵 · H. Asano🇯🇵 · G. Beer🇨🇦 · H. Bhang🇰🇷 · M. Bragadireanu🇷🇴 · P. Buehler🇦🇹 · L. Busso🇮🇹 · M. Cargnelli🇦🇹 · S. Choi🇰🇷 · C. Curceanu🇮🇹 · S. Enomoto🇯🇵 and 58 other authors

   We conducted measurements of $K^{-}+{}^3\mathrm{He}\to \pi YN+N^{\prime }$ reactions using a $1\mathrm{GeV}/c$ $K^{-}$-beam, with the objective of understanding the broad decay width of $\bar{K}NN$ (approximately twice as broad as that of $\Lambda (1405)$ considered to be the $\bar{K}N$ quasi-bound state). We successfully reproduced distributions of the $\pi YN$ invariant mass and momentum transfer for $\pi YN$ using model fitting functions for $\bar{K}NN$ formation and quasi-free $\bar{K}$ absorption (${\mathrm{QF}}_{\bar{K}-\mathrm{abs}}$) processes. The model can describe the experimental data quite well, and four $\bar{K}NN\to \pi YN$ cross-sections were obtained. The results indicate that mesonic decay is the dominant decay branch of $\bar{K}NN$. The results also suggest that ${\Gamma }_{\pi \Lambda N}\sim {\Gamma }_{\pi \Sigma N}$, which indicates that the $I_{\bar{K}N}=1$ absorption channel, in addition to the $I_{\bar{K}N}=0$ absorption channel, substantially contribute to the $\bar{K}NN$ decay, making the $\bar{K}NN$ state approximately twice as unstable as $\Lambda$(1405).

   nucl-exnucl-thPRC(2024)·6 citations
3. 03*

   High-precision measurement of the atomic mass of ${}^{84}$Sr and implications to isotope shift studies

   Zhuang Ge🇫🇮 · Shiwei Bai · Tommi Eronen🇫🇮 · Ari Jokinen🇫🇮 · Anu Kankainen🇫🇮 · Sonja Kujanpää🇫🇮 · Iain Moore🇫🇮 · Dmitrii Nesterenko🇫🇮 · Mikael Reponen🇫🇮

   The absolute mass of ${}^{84}$Sr was determined using the phase-imaging ion-cyclotron-resonance technique with the JYFLTRAP double Penning trap mass spectrometer. A more precise value for the mass of ${}^{84}$Sr is essential for providing potential indications of physics beyond the Standard Model through high-precision isotope shift measurements of Sr atomic transition frequencies. The mass excess of ${}^{84}$Sr was refined to be -80649.229(37) keV/c${}^2$ from high-precision cyclotron-frequency-ratio measurements with a relative precision of 4.8$\times$10${}^{-10}$. The obtained mass-excess value is in agreement with the adopted value in the Atomic Mass Evaluation 2020, but is 30 times more precise. With this new value, we confirm the previously observed nonlinearity in the study of the isotope shift of strontium. Moreover, the double-beta ($2{\beta }^{+}$) decay $Q$ value of ${}^{84}$Sr was directly determined to be 1790.115(37) keV, and the precision was improved by a factor of 30.

   nucl-exphysics.atom-phEPJA(2024)·3 citations
4. 04*

   Impact of The Newly Revised Gravitational Redshift of X-ray Burster GS 1826-24 on The Equation of State of Supradense Neutron-Rich Matter

   Wen-Jie Xie🇨🇳 · Bao-An Li🇺🇸 · Nai-Bo Zhang🇨🇳

   Thanks to the recent advancement in producing rare isotopes and measuring their masses with unprecedented precision, the updated nuclear masses around the waiting-point nucleus ${}^{64}$Ge in the rapid-proton capture process have led to a significant revision of the surface gravitational redshift of the neutron star (NS) in GS 1826-24 by re-fitting its X-ray burst light curve ({\it X. Zhou et al., Nature Physics {\bf 19}, 1091 (2023)}) using Modules for Experiments in Stellar Astrophysics (MESA). The resulting NS compactness $\xi$ is between 0.244 and 0.342 at 95\% confidence level and its upper boundary is significantly smaller than the maximum $\xi$ previously known. Incorporating this new data within a comprehensive Bayesian statistical framework, we investigate its impact on the Equation of State (EOS) of supradense neutron-rich matter and the required spin frequency for GW190814's minor $m_2$ with mass $2.59\pm 0.05$M${}_{\odot }$ to be a rotationally stable pulsar. We found that the EOS of high-density symmetric nuclear matter (SNM) has to be softened significantly while the symmetry energy at supersaturation densities stiffened compared to our prior knowledge from earlier analyses using data from both astrophysical observations and terrestrial nuclear experiments. In particular, the skewness $J_0$ characterizing the stiffness of high-density SNM decreases significantly, while the slope $L$, curvature $K_{\mathrm{sym}}$, and skewness $J_{\mathrm{sym}}$ of nuclear symmetry energy all increase appreciably compared to their fiducial values. We also found that the most probable spin rate for the $m_2$ to be a stable pulsar is very close to its mass-shedding limit once the revised redshift data from GS 1826-24 is considered, making the $m_2$ unlikely the most massive NS observed so far.

   ↳ astro-ph.HEhep-thnucl-exnucl-thPRD(2024)·21 citations
5. 05*

   Uncovering the mechanism of chiral three-nucleon force in driving spin-orbit splitting

   Tokuro Fukui🇯🇵 · Giovanni De Gregorio🇮🇹 · Angela Gargano🇮🇹

   The three-nucleon force (3NF) is crucial in shaping the shell structure of atomic nuclei, particularly impacting the enhancement of spin-orbit (SO) splitting, especially in nuclei with significant deviations from stability. Despite its importance, the specific mechanisms driving this enhancement remain unclear. In this study, we introduce a decomposition scheme based on the rank of irreducible tensors forming the 3NF, derived from chiral effective field theory at next-to-next-to-leading order, to elucidate their influence on SO splitting. Within the shell-model framework, our analysis reveals that the rank-1 component of the 3NF is the primary factor enlarging the energy gap between the $0p_{3/2}$ and $0p_{1/2}$ single-particle levels in $p$-shell nuclei, while the rank-2 component makes a subdominant contribution. Since the rank-1 component originates exclusively from the $2\pi$-exchange 3NF, our finding will not depend on the choice of the low-energy constants of contact terms. We also remark on the antisymmetry of the rank-1 3NF, which can affect the quantum entanglement of spin states. This study lays the groundwork for further exploration into this field toward a microscopic understanding of the 3NF impact on the nuclear shell structure.

   ↳ nucl-thnucl-exPLB(2024)·11 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.