Nuclear Theory·nucl-th

Friday·October 31, 2025

9 papers—4 primary·5 cross-listed

01
Electroweak form factors of large nuclei as BPS skyrmions
Alberte Xosé López Freire · Christoph Adam · Alberto García Martín-Caro · Diego González Díaz
We employ the Bogomolnyi-Prasad-Sommerfield (BPS) Skyrme model within the framework of semi-classical quantization as an effective model to compute both the electromagnetic and neutral current form factors for heavy nuclei. Our results show excellent agreement with the experimental data for low- to moderate momentum transfer. Further, we present an analytic expression of the neutral current form factor for generic nuclei, expressed as a power series in the momentum transfer. Our method provides an alternative to existing phenomenological approaches which, after fitting just one global radial parameter, allows for a surprisingly precise determination of the electroweak form factors at low momentum transfer for all heavy nuclei. Such a simple and robust description is particularly relevant for precision neutrino experiments, because it allows for a certain control over model-dependent systematics, which is essential for probing physics beyond the Standard Model.
nucl-thhep-phhep-th1 citation
02
Sub-barrier fusion enhancement due to positive Q-value four-neutron transfer
Ning Wang · Yi-Jie Duan · Hong Yao · Hui-Ming Jia
The influence of positive $Q$ -value four-neutron transfer (PQ4NT) effects on the sub-barrier capture cross sections is systematically investigated using the empirical barrier distribution (EBD2) method. For 13 fusion reactions with $Q_{4 n} > 0$ , sustained neutron-pair transfer is found to reduce barrier heights and enhance capture cross sections at sub-barrier energies. In contrast, reactions such as $^{18}$ O+ $^{58}$ Ni, which have $Q_{2 n} > 0$ but $Q_{4 n} < 0$ , exhibit no enhancement due to the stalling of subsequent neutron-pair transfer after the initial 2n transfer. By incorporating PQ4NT effects into EBD2 for systems with $Q_{4 n} > 0$ , the average deviation between predicted and experimental capture cross sections (113 datasets) is significantly reduced by $20%$ . Additionally, comparing with the systems induced by $^{48}$ Ca ( $Q_{4 n} < 0$ ), much larger neutron pickup probabilities are observed in the quasi-elastic scattering of $^{40}$ Ca-induced reactions ( $Q_{4 n} > 0$ ) from the time-dependent Hartree-Fock (TDHF) calculations.
nucl-thCPC(2026)·2 citations
03
Energy Dependence of Elliptic Flow Ratio $v_{2}^{PP}$ / $v_{2}^{RP}$ in Heavy-ion Collisions Using the AMPT Model
Shaowei Lan🇨🇳 · Qiuhua Liu🇨🇳 · Yong Li🇨🇳 · Shusu Shi🇨🇳
We present a systematic study of the elliptic flow $v_{2}$ relative to the participant plane (PP) and reaction plane (RP) in Au+Au collisions at $s_{N N} = 7.7$ -200 GeV using the AMPT model with the string melting version. The ratio $v_{2}^{PP}$ / $v_{2}^{RP}$ is investigated under different hadronic cascade times (0.6 fm/ $c$ , 10 fm/ $c$ , and the maximum evolution time) and across various collision centralities. The results show that, at a fixed collision energy, the ratio exhibits negligible sensitivity to the duration of the hadronic rescattering stage, indicating that hadronic interactions have little effect on the relative difference generated by initial-state fluctuations. However, a strong energy dependence is observed, the ratio increases with beam energy and saturates above $s_{N N} \approx 62.4$ GeV, a trend that persists across all centralities. These findings highlight the dominant role of the partonic phase in converting initial-state geometry fluctuations into final-state momentum anisotropy. Conversely, at lower energies, the reduced partonic interaction strength limits this conversion efficiency, weakening the system's ability to preserve the initial geometric information. Our results suggest that the conversion of initial geometric fluctuations into final momentum anisotropy requires sufficient partonic interactions.
nucl-thhep-exCPC(2026)·0 citations
04
One-pion exchange potential in a strong magnetic field
Daiki Miura🇯🇵 · Masaru Hongo🇯🇵 · Hidetoshi Taya🇯🇵 · Tetsuo Hatsuda🇯🇵
We derive the one-pion exchange potential (OPEP) in the presence of a homogeneous magnetic field using chiral perturbation theory with nonrelativistic nucleons. Our approach is applicable not only to weak magnetic fields but also to strong ones up to around the pion-mass scale. The Green's function of charged pions is modified by the magnetic field, leading to changes in the nuclear force. By numerically evaluating the modified OPEP incorporating its spin and isospin dependencies, we show that the range of the potential decreases in both directions parallel and perpendicular to the magnetic field as the field strength increases. We also compute the resulting energy shift of the deuteron due to the modified OPEP, which can reach the order of 1 MeV around $∣ e B ∣ = m_{π}^{2}$ , which is comparable to the deuteron binding energy.
nucl-thhep-phhep-thnucl-exPTEP(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Electroweak form factors of large nuclei as BPS skyrmions

Sub-barrier fusion enhancement due to positive Q-value four-neutron transfer

Energy Dependence of Elliptic Flow Ratio v2PP​/v2RP​ in Heavy-ion Collisions Using the AMPT Model

One-pion exchange potential in a strong magnetic field

Affiliations

Energy Dependence of Elliptic Flow Ratio $v_{2}^{PP}$ / $v_{2}^{RP}$ in Heavy-ion Collisions Using the AMPT Model