包含显式Δ(1232)自由度的中子β衰变辐射修正
Radiative corrections to neutron $β$ decay with explicit $Δ(1232)$ degrees of freedom
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中文总结 AI 辅助
该研究在含Δ(1232)共振的手征微扰理论中计算中子β衰变的电磁辐射修正，发现轴耦合电磁修正减半，还得到量级更小的Δ诱导弱磁项，对核子轴荷的实验与格点QCD对比有意义。
中文摘要 AI 辅助
我们在扩展至包含Δ(1232)共振作为显式自由度的手征微扰理论框架内，研究中子β衰变的电磁辐射修正。基于此前无Δ共振理论框架下的分析，我们在小尺度展开的领头阶和次领头阶识别并计算了含中间Δ态的额外圈图贡献，并将结果与无π有效场论进行匹配。我们发现，轴耦合的电磁修正相比无Δ共振理论的结果减少了约一半，该修正仍处于百分比量级，对实验提取与格点量子色动力学（lattice-QCD）确定核子轴荷的对比具有重要的物理意义。我们还得到了由Δ共振诱导的弱磁项新贡献，其量级比π圈图结果小一个数量级，对即将开展的实验可忽略不计。
英文摘要
We study electromagnetic radiative corrections to neutron $β$ decay within chiral perturbation theory extended to include the $Δ(1232)$ resonance as an explicit degree of freedom. Building on a previous analysis performed in the $Δ$-less theory, we identify and compute additional loop contributions with intermediate $Δ$ states at leading and next-to-leading order in the small-scale expansion, and match the results to the pionless effective field theory. We find that the convergence of the chiral expansion significantly improved in the $Δ$-full calculation. The electromagnetic shift in the axial coupling is reduced by $25\%$ compared to the $Δ$-less result. The correction remains at the percent level and is phenomenologically significant for the comparison between experimental extractions and lattice-QCD determinations of the nucleon axial charge. We also obtain a new $Δ$-induced contribution to the weak magnetism term, which is an order of magnitude smaller than the pion-loop result and negligible for upcoming experiments.
发表机构
- University of Amsterdam（阿姆斯特丹大学）
- Nikhef, Theory Group（尼赫夫理论组）
- Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室）
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