Electromagnetic mass splittings of the low lying hadrons and quark masses from 2+1 flavor lattice QCD+QED
Electromagnetic mass splittings of the low lying hadrons and quark masses from 2+1 flavor lattice QCD+QED
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DOI：
10.1103/physrevd.82.094508
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发表时间：
2010-06
影响因子：
5
通讯作者：
T. Blum;T. Doi;M. Hayakawa;T. Izubuchi;S. Uno;N. Yamada;R. Zhou
中科院分区：
文献类型：
--
作者：
T. Blum;T. Doi;M. Hayakawa;T. Izubuchi;S. Uno;N. Yamada;R. Zhou
给出了低位强子电磁质量分裂的晶格 QCD+QED 计算结果。这些用于确定重整化的、非简并的轻夸克质量。结果发现，在重正化尺度2 GeV下，m{sub u}{sup MS}=2.24(10)(34)，m{sub d}{sup MS}=4.65(15)(32)，m{sub s}{sup MS}=97.6(2.9)(5.5) MeV，其中第一个误差是统计误差，第二个误差是系统误差。我们发现最低阶电磁分裂 (m{sub {pi}{sup +}}-m{sub {pi}{sup 0}}){sub QED}=3.38(23) MeV，分裂包括次高阶，(m{sub {pi}{sup +}}-m{sub {pi}{sup 0}}){sub QED}=4.50(23) MeV，(m{sub K{sup +}}-m{sub K{sup 0}}){sub QED}=1.87(10) MeV，以及 m{sub u}{ne}m{sub d} 对 kaon 质量差的贡献，(m{sub K{sup +}}-m{sub K{sup 0}}){sub (m{sub u}-m{sub d})}=-5.840(96) MeV。所有误差仅是统计性的，并且次前导π介子分裂只是近似的，因为它不包含所有次前导贡献。我们还计算了质子-中子质量差，包括首次在真实的 2+1 风味计算中计算 QED 相互作用。我们发现 (m{sub p}-m{sub n}){sub QED}=0.383(68) MeV，(m{sub p}-m{sub n}){sub (m{sub u}-m{sub d})}=-2.51(14) MeV（仅统计误差），以及总 m{sub p}-m{sub n}=-2.13(16)(70) MeV，其中第一个误差是统计误差，第二个误差是系统误差的一部分。计算是在 RBC 和 UKQCD 合作生成的 QCD 系综上进行的，使用域壁费米子和岩崎规范作用（规范耦合 {beta}=2.13 和晶格截止 a{sup -1}{approx_equal}1.78 GeV）。我们使用两种晶格尺寸：16{sup 3} 和 24{sup 3}（(1.8 fm){sup 3} 和 (2.7 fm){sup 3}）来解决有限体积效应。非紧致 QED 采用淬火近似处理。我们研究中的价态赝标量介子质量涵盖约 250 至 700 MeV 的范围，但我们仅使用高达约 400 MeV 的值来引用最终结果。我们提出了 SU(3) 和 SU(2) 部分淬灭手性微扰理论中电磁低能常数的新结果，这些结果是通过对我们的数据进行拟合而获得的。讨论了我们结果中的系统误差的详细分析以及改进方法。最后，给出了 SU(2){sub L}xSU(2){sub R}-plus-kaon 手性微扰理论的新解析结果，包括与 {alpha}{sub em}m 成比例的单环对数。« less
Results computed in lattice QCD+QED are presented for the electromagnetic mass splittings of the low-lying hadrons. These are used to determine the renormalized, nondegenerate, light quark masses. It is found that m{sub u}{sup MS}=2.24(10)(34), m{sub d}{sup MS}=4.65(15)(32), and m{sub s}{sup MS}=97.6(2.9)(5.5) MeV at the renormalization scale 2 GeV, where the first error is statistical and the second systematic. We find the lowest-order electromagnetic splitting (m{sub {pi}{sup +}}-m{sub {pi}{sup 0}}){sub QED}=3.38(23) MeV, the splittings including next-to-leading order, (m{sub {pi}{sup +}}-m{sub {pi}{sup 0}}){sub QED}=4.50(23) MeV, (m{sub K{sup +}}-m{sub K{sup 0}}){sub QED}=1.87(10) MeV, and the m{sub u}{ne}m{sub d} contribution to the kaon mass difference, (m{sub K{sup +}}-m{sub K{sup 0}}){sub (m{sub u}-m{sub d})}=-5.840(96) MeV. All errors are statistical only, and the next-to-leading-order pion splitting is only approximate in that it does not contain all next-to-leading-order contributions. We also computed the proton-neutron mass difference, including for the first time, QED interactions in a realistic 2+1 flavor calculation. We find (m{sub p}-m{sub n}){sub QED}=0.383(68) MeV, (m{sub p}-m{sub n}){sub (m{sub u}-m{sub d})}=-2.51(14) MeV (statistical errors only), and the total m{sub p}-m{sub n}=-2.13(16)(70) MeV, where the first error is statistical, and the second, part of the systematic error. The calculations are carried out on QCD ensembles generated bymore » the RBC and UKQCD collaborations, using domain wall fermions and the Iwasaki gauge action (gauge coupling {beta}=2.13 and lattice cutoff a{sup -1}{approx_equal}1.78 GeV). We use two lattice sizes, 16{sup 3} and 24{sup 3} ((1.8 fm){sup 3} and (2.7 fm){sup 3}), to address finite-volume effects. Noncompact QED is treated in the quenched approximation. The valence pseudoscalar meson masses in our study cover a range of about 250 to 700 MeV, though we use only those up to about 400 MeV to quote final results. We present new results for the electromagnetic low-energy constants in SU(3) and SU(2) partially quenched chiral perturbation theory to the next-to-leading order, obtained from fits to our data. Detailed analysis of systematic errors in our results and methods for improving them are discussed. Finally, new analytic results for SU(2){sub L}xSU(2){sub R}-plus-kaon chiral perturbation theory, including the one-loop logs proportional to {alpha}{sub em}m, are given.« less