Nuclear Theory·nucl-th

Monday·April 21, 2025

6 papers—3 primary·3 cross-listed

01
Refinement of an analytical capture cross section formula
Ning Wang
An analytical formula with high accuracy is proposed for a systematic description of the capture cross sections at near-barrier energies from light to superheavy reaction systems. Based on the empirical barrier distribution (EBD) method, three key input quantities are refined by introducing nuclear surface correction to the Coulomb parameter $z$ for calculating the barrier height, incorporating the reaction $Q$ -value and shell correction into the barrier distribution width calculations, and considering the deep inelastic scattering effects of superheavy systems on the barrier radius. With these refinements, not only the accuracy of the calculated barrier height but also the accuracy of the predicted capture cross sections, is substantially improved. The average deviation (in logarithmic scale) between the predicted cross sections and the experimental data for a total of 426 reaction systems with $35 < Z_{1} Z_{2} < 2600$ is sharply reduced from 3.485 to 0.113.
nucl-thnucl-exCPC(2025)·3 citations
02
Charge radii and their deformation correlation for even- $Z$ nuclei in deformed relativistic Hartree-Bogoliubov theory in continuum
C. Pan · J. Meng
The systematics are investigated for the charge radii of the even- $Z$ nuclei with $8 ⩽ Z ⩽ 120$ calculated by the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the functional PC-PK1, and their deformation correlation is explored. The available data of the charge radius are reproduced with a root-mean-square deviation $σ = 0.033$ fm. In particular, for the nuclei between the closed shells, the descriptions of the charge radii are remarkably improved by including the deformation. Taking molybdenum isotopes as examples, both the evolutions of the charge radius and deformation are well reproduced. It is found that while the charge radius typically increases with the deformation, there also exist different cases. For example, in $^{346}$ Sg, the charge radius of the deformed ground state is smaller than the one of the spherical state, and the largest binding energy does not necessarily correspond to the smallest charge radius. The increase or decrease of the charge radii with deformation is related to specific shell structures, particularly the key single-particle levels near the Fermi energy.
nucl-thPRC(2025)·13 citations
03
Productions of $_{Λ}^{3}$ H, $_{Λ}^{4}$ H and $_{Λ}^{4}$ He in different coalescence channels in Au-Au collisions at $s_{N N} = 3$ GeV
Rui-Qin Wang🇨🇳 · Jun Song🇨🇳 · Mao-Yan Wu🇨🇳 · Huai-Tong Xue🇨🇳 · Feng-Lan Shao🇨🇳
We study the productions of $Λ$ -hypernuclei $_{Λ}^{3}$ H, $_{Λ}^{4}$ H and $_{Λ}^{4}$ He in the coalescence mechanism in Au-Au collisions at $s_{N N} = 3$ GeV. Considering the abundance and great importance of baryons and light (hyper-)nuclei on the collision dynamics, we include not only nucleon $+ Λ$ coalescence but also nucleus+nucleon( $Λ$ ) coalescence. We present contributions from different coalescence channels for $_{Λ}^{3}$ H, $_{Λ}^{4}$ H and $_{Λ}^{4}$ He in their productions. We predict the production asymmetry between $_{Λ}^{4}$ H and $_{Λ}^{4}$ He, characterized by yield ratios $_{Λ}^{4} He /_{Λ}^{4} H$ and $(_{Λ}^{4} H -_{Λ}^{4} He) / (_{Λ}^{4} H +_{Λ}^{4} He)$ , which can shed light on the existence constraints of the possible neutron- $Λ$ bound states $_{Λ}^{2} n (n Λ)$ and $_{Λ}^{3} n (nn Λ)$ .
nucl-thhep-exhep-phnucl-exPRC(2025)·2 citations
04
The Unitarity-Limit Expansion for Two Nucleons with Perturbative Pions: Digest and Ideas
Harald W. Griesshammer (George Washington U.)🇺🇸
In the Unitarity Limit, the NN S-wave binding energies are zero, the scattering lengths infinite, Physics is universal, i.e. insensitive to details of the interactions, and observables display richer symmetries, namely invariance under both scaling and Wigner's combined SU(4) transformation of spin and isospin. This presentation is a digest of the first quantitative exploration of corrections to this picture when pions are included [1] (see there for a more comprehensive list of references). Since the pion mass and decay constant introduce dimensionful scales in the NN system, they explicitly break the symmetries of the Unitarity fixed point. In $χ$ EFT, these symmetries must therefore be classified as emergent. This text focuses on the $χ$ EFT variant with Perturbative ("KSW") Pions at next-to-next-to leading order (N2LO). This leads to the Hypothesis that both scale invariance and Wigner-SU(4) symmetry in the Unitarity Expansion show persistence, i.e. the footprint of both combined dominates even for $k ≳ m_{π}$ and is more relevant than chiral symmetry, so that the tensor/Wigner-SU(4) symmetry-breaking part of OPE is suppressed and does not enter before N3LO. Included are also ideas about underlying mechanisms and LO results of $χ$ EFT with Nonperturbative Pions in the expansion about Unitarity.
↳ nucl-thhep-phphysics.atom-phPoS(2026)·2 citations
05
The impact of new ( $α$ , n) reaction rates on the weak s-process in metal-poor massive stars
Wenyu Xin · Chun-Ming Yip · Ken'ichi Nomoto · Xianfei Zhang · Shaolan Bi
Massive stars are significant sites for the weak s-process (ws-process). $^{22}$ Ne and $^{16}$ O are, respectively, the main neutron source and poison for the ws-process. In the metal-poor stars, the abundance of $^{22}$ Ne is limited by the metallicity, so that the contribution of $^{22}$ Ne( $α$ , n) $^{25}$ Mg reaction on the s-process is weaker. Conversely, the $^{17}$ O( $α$ , n) $^{20}$ Ne reaction becomes more prominent in these stars due to the most abundant $^{16}$ O in all metallicities. In this work, we calculate the evolution of four metal-poor models ( $Z = 1 0^{- 3}$ ) for the Zero-Age Main-Sequence (ZAMS) masses of $M (ZAMS) =$ 15, 20, 25, and 30 M $_{⊙}$ to investigate the effect of reaction rates on the ws-process. We adopt the new $^{17}$ O( $α$ , n) $^{20}$ Ne and $^{17}$ O( $α, γ$ ) $^{21}$ Ne reaction rates suggested by Best et al. (2013) and $^{22}$ Ne( $α$ , n) $^{25}$ Mg and $^{22}$ Ne( $α, γ$ ) $^{26}$ Mg from Wiescher et al. (2023). The yields of the s-process isotope with updated reaction rates are compared with the results using default reaction rates from JINA REACLIB. We find that the new $^{17}$ O+ $α$ reaction rates increase the ws-process mainly in all the stages, while the new $^{22}$ Ne+ $α$ reaction rates only increase the ws-process in C and Ne burning stages. Updating these new reaction rates would increase the production of ws-process isotopes by tens of times. We also note that for more massive stars, the enhancement by new $^{17}$ O+ $α$ reaction rates become more significant.
↳ astro-ph.SRnucl-exnucl-thNucl.Sci.Tech.(2026)·1 citation
06
Extracting the chiral anomaly from $e^{+} e^{-} \to 3 π$
Martin Hoferichter🇨🇭 · Bai-Long Hoid🇩🇪 · Bastian Kubis🇩🇪
The strength of the interaction of three pions and a photon, $F_{3 π}$ is predicted by the axial anomaly in terms of the pion decay constant, a relation that is frequently used to constrain low-energy radiative processes involving pions, but only tested experimentally at the $10%$ level. Here, we present a new avenue to test this prediction, via a fit of a dispersive description of the $γ^{*} \to 3 π$ amplitude to data for $e^{+} e^{-} \to 3 π$ . From the global fit to SND, CMD-2, and BaBar data we obtain $F_{3 π} = 33.1 (1.7) GeV^{- 3}$ , in agreement with the chiral prediction at the level of $5%$ . We also consider dispersive fits to the recent data by Belle II, in which case we observe tensions with the dispersive constraints, the width parameters of $ω$ and $ϕ$ , and the chiral anomaly.
↳ hep-phhep-exhep-latnucl-thJHEP(2025)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE

Refinement of an analytical capture cross section formula

Charge radii and their deformation correlation for even-Z nuclei in deformed relativistic Hartree-Bogoliubov theory in continuum

Productions of Λ3​H, Λ4​H and Λ4​He in different coalescence channels in Au-Au collisions at sNN​​=3 GeV

The Unitarity-Limit Expansion for Two Nucleons with Perturbative Pions: Digest and Ideas

The impact of new (α, n) reaction rates on the weak s-process in metal-poor massive stars

Extracting the chiral anomaly from e+e−→3π

Affiliations

Charge radii and their deformation correlation for even- $Z$ nuclei in deformed relativistic Hartree-Bogoliubov theory in continuum

Productions of $_{Λ}^{3}$ H, $_{Λ}^{4}$ H and $_{Λ}^{4}$ He in different coalescence channels in Au-Au collisions at $s_{N N} = 3$ GeV

The impact of new ( $α$ , n) reaction rates on the weak s-process in metal-poor massive stars

Extracting the chiral anomaly from $e^{+} e^{-} \to 3 π$