Mon·Jun 30, 2025Monday·June 30, 2025

1. 01*

   Universal Effective Charges in the $sd$ and $fp$ Shells

   T. H. Ogunbeku🇺🇸 · J. M. Allmond🇺🇸 · T. J. Gray🇺🇸 · W.-J. Ong🇺🇸 · B. A. Brown🇺🇸 · A. Gargano🇮🇹 · R. Grzywacz🇺🇸 · J. D. Holt🇨🇦 · A. O. Macchiavelli🇺🇸 · T. Miyagi🇩🇪 · S. Neupane🇺🇸 · B. C. Rasco🇺🇸 and 70 other authors

   The 247-keV state in ${}^{54}$Sc, populated in the $\beta$ decay of ${}^{54}$Ca, is reported here as a nanosecond isomer with a half-life of 26.0(22) ns. The state is interpreted as the $1^{+}$ member of the $\pi f_{7/2}\otimes \nu f_{5/2}$ spin-coupled multiplet, which decays to the $3^{+},\pi f_{7/2}\otimes \nu p_{1/2}$ ground state. The new half-life corresponds to a pure $E2$ transition with a strength of 1.93(16) W.u., providing the most precise, unambiguous $B(E2)$ value in the neutron-rich $fp$ region to date for a nucleus with valence protons above $Z=20$. Notably, it is roughly four times larger than the $B(E2;1/2^{-}\to 5/2^{-})$ value in ${}^{55}$Ca. The results, as compared to semi-empirical and ab initio shell-model calculations, indicate (1) a weak $N=34$ sub-shell gap relative to $N=32$, (2) a large $E2$ enhancement in Sc as compared to Ca due to $1p-1h$ proton excitations across $Z=28$, and (3) empirical effective proton and neutron charges, $e_{\pi }$ = 1.30(8)$e$ and $e_{\nu }$ = 0.452(7)$e$, respectively, that are in contrast to reports of $e_{\pi }\approx 1.1-1.15e$ and $e_{\nu }\approx 0.6-0.8e$ for $fp$-shell nuclei near $N=Z$. We demonstrate that these reports are erroneous and that, in fact, a universal set of effective charges can be used across the $sd$ and $fp$ shells.

   nucl-exnucl-thPRL(2025)·9 citations
2. 02*

   Intruder structures in ${}^{32}$Si and ${}^{29}$Al

   J. Williams🇨🇦 · G. Hackman🇨🇦 · K. Starosta🇨🇦 · R. S. Lubna🇺🇸 · Priyanka Choudhary🇮🇳 · Subhrajit Sahoo🇮🇳 · P. C. Srivastava🇮🇳 · C. Andreoiu🇨🇦 · D. Annen🇨🇦 · H. Asch🇨🇦 · M. D. H. K. G. Badanage🇨🇦 · G. C. Ball🇨🇦 and 22 other authors

   We have studied ${}^{32}$Si and ${}^{29}$Al using ${}^{12}$C(${}^{22}$Ne,2p) and ${}^{12}$C(${}^{22}$Ne,$\alpha$p) fusion-evaporation reactions. In both cases, we observed significant population of high-spin structures distinct from the ground-state yrast bands. In ${}^{32}$Si, most of the high-energy states feed into a $J^{\pi }=5^{-}$ nanosecond isomer. In ${}^{29}$Al, we identified a rotor-like negative-parity band with a $J^{\pi }=7/2^{-}$ band-head. Doppler shift lifetime measurements were performed for all observed states. These results were compared to shell model calculations and interpreted in terms of proton and neutron cross-shell excitation.

   nucl-exPRC(2025)·2 citations
3. 03*

   Charm production and fragmentation fractions at midrapidity in pp collisions at the LHC with ALICE

   Renu Bala (for the ALICE Collaboration)🇮🇳

   Heavy quarks, such as charm and beauty, possess masses significantly larger than the characteristic energy scale of Quantum Chromodynamics (QCD), and are thus predominantly produced in hard-scattering processes with large momentum transfer ($Q^2$). This makes them effective probes for verifying QCD calculations and investigating heavy-quark hadronization processes across various collision systems. Recent measurements of charm meson and baryon production in proton--proton (pp) collisions at the LHC have enabled, for the first time, a determination of the total charm production cross section, including contributions from all ground-state charm hadrons.Additionally, the fragmentation fractions of charm quarks into hadrons in pp collisions have been quantified.

   ↳ hep-exnucl-exJ.Subatomic Part.Cosmol.(2025)·1 citation
4. 04*

   Magneto-Thomson and transverse Thomson effects in an interacting hadron gas in the presence of an external magnetic field

   Kamaljeet Singh🇮🇳 · Kshitish Kumar Pradhan🇮🇳 · Raghunath Sahoo🇮🇳

   The universality of electric charge as a quantum number allows thermoelectric properties to manifest across diverse systems, starting from a hot quantum chromodynamic matter in heavy-ion collisions at a high energy scale to semiconductors in condensed matter systems at a low energy scale. In this work, we explore the emergence of magneto-transport phenomena, specifically the magneto-Thomson and transverse Thomson effects, in a hot and dense hadronic medium produced in relativistic heavy-ion collisions at the Relativistic Heavy Ion Collider and Large Hadron Collider energies. These phenomena arise due to the combined influence of temperature gradients and non-zero baryon chemical potential, particularly in the presence of an external magnetic field. Using the relativistic Boltzmann transport equation within the relaxation time approximation, we analyze the behavior of the hadronic medium considering different frameworks of hadron resonance gas models. The presence of external magnetic fields breaks the isotropy of the thermoelectric transport coefficient matrix, giving rise to new components of the Thomson coefficient, namely, magneto-Thomson and transverse Thomson coefficients. For the first time, we estimate the magneto-Thomson and transverse Thomson coefficients, which originate from the temperature dependence of the magneto-Seebeck coefficient and Nernst coefficient, respectively, in hadron gas under the influence of a static and time-varying magnetic field. Our findings provide a novel perspective on the higher-order thermoelectric properties of the hot and dense hadronic medium in the context of heavy-ion collisions.

   ↳ hep-phhep-exhep-thnucl-ex+1PRD(2026)·1 citation
5. 05*

   Spin polarization from nucleon-nucleon scatterings in intermediate-energy heavy-ion collisions

   Rong-Jun Liu🇨🇳 · Jun Xu🇨🇳 · Yu-Gang Ma🇨🇳

   We propose a new mechanism of generating spin polarization in heavy-ion collisions dominated by nucleon degree of freedom. By incorporating the spin change in nucleon-nucleon scatterings based on the phase shift data together with the constraint of rigorous angular momentum conservation and Pauli blocking, we illustrate through a Boltzmann-Uehling-Uhlenbeck transport model that appreciable spin polarization (about $1\sim 2\%$) can be generated in intermediate-energy heavy-ion collisions. This mechanism, together with the nuclear spin-orbit potential, may help to understand the spin polarization in few-GeV heavy-ion collisions dominated by nucleon degree of freedom.

   ↳ nucl-thhep-exnucl-exPLB(2025)·4 citations
6. 06*

   Meson-baryon scattering lengths without annihilation diagrams to order $p^4$ in heavy baryon chiral perturbation theory

   Jing Ou-Yang🇨🇳 · Ke Wang🇨🇳 · Bo-Lin Huang🇨🇳

   We calculate the threshold $T$ matrices of the meson and baryon processes that have no annihilation diagrams: ${\pi }^{+}{\Sigma }^{+}$, ${\pi }^{+}{\Xi }^0$, $K^{+}p$, $K^{+}n$, and ${\bar{K}}^0{\Xi }^0$ to the fourth order in heavy baryon chiral perturbation theory. By performing least squares and Bayesian fits to the non-physical lattice QCD data, we determine the low-energy constants through both perturbative and non-perturbative iterative methods. By using these low-energy constants, we obtain the physical scattering lengths in these fits. The convergence behavior is not good across all channels in the perturbative method. The scattering lengths for the five channels, obtained by taking the median values from four different fitting approaches, are $a_{{\pi }^{+}{\Sigma }^{+}}=-0.16\pm 0.07\text{fm}$, $a_{{\pi }^{+}{\Xi }^0}=-0.04\pm 0.04\text{fm}$, $a_{K^{+}p}=-0.41\pm 0.11\text{fm}$, $a_{K^{+}n}=-0.19\pm 0.10\text{fm}$, and $a_{{\bar{K}}^0{\Xi }^0}=-0.30\pm 0.07\text{fm}$, where the uncertainties are conservatively estimated by taking the maximum deviation between the median and extreme values of the statistical errors.

   ↳ hep-phhep-latnucl-exnucl-thPRD(2025)·1 citation
7. 07*

   Exploring hadronic rescattering effects on resonance productions in pp and p-Pb collisions with PYTHIA8

   Su-Jeong Ji🇰🇷 · Gyeongbin Park🇰🇷 · Bong-Hwi Lim🇯🇵 · Sanghoon Lim🇰🇷

   In relativistic heavy-ion collisions, the quark-gluon plasma is created, and as the medium cools down, the system transitions into a hadronic phase. While such interactions are well established for large systems, such as Pb-Pb collisions, their relevance in smaller collision systems remains unclear. Consequently, hadronic interactions during the hadronic phase are studied in pp collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the PYTHIA8 event generator. The interaction is studied via the yield ratios between resonances and stable particles with similar quark contents, which are obtained as a function of transverse momentum ($p_{\mathrm{T}}$) using $\rho (770{)}^0$, ${\mathrm{K}}^{\ast }(892{)}^0$, and $\varphi (1020)$ mesons and their stable particles, ${\pi }^{\pm }$ and ${\mathrm{K}}^{\pm }$ at midrapidity ($|\mathrm{y}|<0.5$). Yield ratios are calculated in five multiplicity classes for pp and six for p-Pb collisions, using the 60-100% multiplicity class in pp as a reference. Although rescattering leads to stronger suppression at low $p_{\mathrm{T}}<2$ GeV/$c$, a visible suppression remains even when rescattering is turned off. To isolate the rescattering effect, double ratios between the rescattering on and off configurations are obtained. These are then integrated in the full $p_{\mathrm{T}}$ range ($0<p_{\mathrm{T}}<6.0$ GeV/$c$). The normalized double ratios show a decreasing trend with increasing multiplicity, independent of the collision system. The lower limit of the hadronic phase lifetimes extracted in the integrated-$p_{\mathrm{T}}$ region increases with multiplicity in both systems, but with a notable discrepancy between pp and p-Pb collisions.

   ↳ nucl-thnucl-exNPA(2026)·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.