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arXiv 1903.08078nucl-thnucl-ex
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原子核中μ子俘获的量子Monte Carlo从头计算方法

Muon capture in nuclei: an ab initio approach based on quantum Monte Carlo methods

A. Lovato, N. Rocco, R. Schiavilla

摘要:

介绍了一种计算质量数为$A \leq 12$的轻核中μ子弱俘获总速率的从头计算量子蒙特卡罗方法。作为该方法的第一个应用程序,我们进行了计算率在$^4$他在一个动态框架的基础上现实的两个和三个核子相互作用和现实的核电荷变化弱电流。电流包括由$π$ -和$ρ$ -介子交换,以及$N$ -到- $Δ$激发引起的一体项和二体项,并且被约束以再现氚中伽莫夫-泰勒矩阵元素的经验值。我们研究了理论预言对核子轴向和感生赝标形状因子电流参数化的敏感性以及对弱电流中两体贡献的敏感性。气泡室实验(50多年前进行的)测得的值存在很大的不确定性,这使我们无法得出任何明确的结论。

英文摘要:

An ab initio quantum Monte Carlo method is introduced for calculating total rates of muon weak capture in light nuclei with mass number $A \leq 12$. As a first application of the method, we perform a calculation of the rate in $^4$He in a dynamical framework based on realistic two- and three-nucleon interactions and realistic nuclear charge-changing weak currents. The currents include one- and two-body terms induced by $π$- and $ρ$-meson exchange, and $N$-to-$Δ$ excitation, and are constrained to reproduce the empirical value of the Gamow-Teller matrix element in tritium. We investigate the sensitivity of theoretical predictions to current parametrizations of the nucleon axial and induced pseudoscalar form factors as well as to two-body contributions in the weak currents. The large uncertainties in the measured values obtained from bubble-chamber experiments (carried out over 50 years ago) prevent us from drawing any definite conclusions.

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