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arXiv 1208.4185hep-lathep-ph
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具有精确手征对称性的N_f=2+1格点量子色动力学的核子奇夸克含量

Nucleon strange quark content from N_f=2+1 lattice QCD with exact chiral symmetry

JLQCD Collaboration, H. Ohki, K. Takeda, S. Aoki, S. Hashimoto, T. Kaneko, H. Matsufuru, J. Noaki, T. Onogi

摘要:

计算了2+1味格点量子色动力学中核子的奇异夸克含量。手征对称重叠费米子表述用于避免由于奇异标量算符和轻标量算符\bar{s} s和\bar{u} u+ \bar{d} d之间的算符混合而引起的上夸克和下夸克含量的污染。在晶格间距a=0.112(1)fm时,我们计算了四种简并上夸克和下夸克质量,它们覆盖了π介子质量M_pi \simeq 300-540 MeV的范围。我们采用了两种不同的方法:一种是直接方法,通过直接插入奇异标量算符来计算奇异夸克含量。另一种是间接的方法,夸克含量是从核子质量对奇异夸克质量的导数中提取出来的。用这两种方法得到了相互一致的结果。我们的最佳估计值f_{T_s} =0.009(15)(16)与我们以前在双味QCD中的研究结果吻合得很好。

英文摘要:

We calculate the strange quark content of the nucleon in 2+1-flavor lattice QCD. Chirally symmetric overlap fermion formulation is used to avoid the contamination from up and down quark contents due to an operator mixing between strange and light scalar operators, \bar{s}s and \bar{u}u+\bar{d}d. At a lattice spacing a=0.112(1) fm, we perform calculations at four values of degenerate up and down quark masses, which cover a range of the pion mass M_pi \simeq 300-540 MeV. We employ two different methods: one is a direct method where we calculate the strange quark content by directly inserting the strange scalar operator. The other is an indirect method where the quark content is extracted from a derivative of the nucleon mass in terms of the strange quark mass. With these two methods we obtain consistent results with each other. Our best estimate f_{T_s}=0.009(15)(16) is in good agreement with our previous studies in two-flavor QCD.

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