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arXiv 1901.07519hep-lathep-phnucl-th
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用物理夸克质量确定中子-反中子矩阵元的格点量子色动力学

Lattice QCD determination of neutron-antineutron matrix elements with physical quark masses

Enrico Rinaldi, Sergey Syritsyn, Michael L. Wagman, Michael I. Buchoff, Chris Schroeder, Joseph Wasem

摘要:

六夸克算符的矩阵元是从中子-反中子振荡的实验研究中提取新的物理约束所必需的。本文详细介绍了中子-反中子跃迁所需矩阵元的第一格点量子色动力学计算,包括计算方法和系统不确定性的讨论。讨论了六夸克算符的矩阵元、同位旋极限下的幂次计数和手征基重正化对同位旋和手征对称性的影响。为了避免手征外推的需要,计算进行了夸克作用和物理轻夸克质量的手征对称离散化。非微扰重整化进行,包括晶格截止效应的研究。使用两个核子算符和多个源-汇分离值研究了激发态效应。主导矩阵元素的结果被发现是显着大于以前的结果相比,从麻省理工学院袋模型。未来的计算需要充分考虑与离散化和有限体积效应相关的系统不确定性,但预计不会对这一结论产生重大影响。

英文摘要:

Matrix elements of six-quark operators are needed to extract new physics constraints from experimental searches for neutron-antineutron oscillations. This work presents in detail the first lattice quantum chromodynamics calculations of the necessary neutron-antineutron transition matrix elements including calculation methods and discussions of systematic uncertainties. Implications of isospin and chiral symmetry on the matrix elements, power counting in the isospin limit, and renormalization of a chiral basis of six-quark operators are discussed. Calculations are performed with a chiral-symmetric discretization of the quark action and physical light quark masses in order to avoid the need for chiral extrapolation. Non-perturbative renormalization is performed, including a study of lattice cutoff effects. Excited-state effects are studied using two nucleon operators and multiple values of source-sink separation. Results for the dominant matrix elements are found to be significantly larger compared to previous results from the MIT bag model. Future calculations are needed to fully account for systematic uncertainties associated with discretization and finite-volume effects but are not expected to significantly affect this conclusion.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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