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arXiv 1503.08440hep-lathep-ph
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格点量子色动力学中的粲重子谱和光味对称性

Charmed baryon spectroscopy and light flavour symmetry from lattice QCD

Gunnar Bali, Sara Collins, Paula Pérez-Rubio

摘要:

本文确定了自旋为1/2和3/2的正负宇称单粲和双粲重子的基态和第一激发态质量。用$N_f=2+1$非微扰改进的Wilson-clover费米子进行了量子化,同样的夸克作用量也用于价夸克,包括粲夸克。该谱是在$M_π\sim 259-460$ MeV的范围内,以$a\sim 0.075$ fm的晶格间距计算的π介子质量。有限体积效应进行了研究,比较两种不同的线性空间范围($1.8\,{\rm fm}$和$2.4\,{\rm fm}$)的晶格。物理点从SU(3)极限接近,保持味平均轻夸克质量不变。重子的质量外推使用展开的奇异轻夸克质量差。大多数粒子都属于预期的SU(3)多重态,具有良好的约束外推,例外情况可能具有更复杂的内部结构。对单粲重子的质量和分裂的计算结果与实验结果基本一致。作为计算的一部分,对低位粲偶素、$D$和$D_s$光谱进行分析,以评估离散化误差。再现了包括$D^*_{s0}$、$D_{s1}$和$D_1$介子的总谱,而在这个单一晶格间距下超精细分裂得到的$10-20$ MeV太低。

英文摘要:

We determine the ground state and first excited state masses of singly and doubly charmed spin 1/2 and 3/2 baryons with positive and negative parity. Configurations with $N_f=2+1$ non-perturbatively improved Wilson-clover fermions were employed, with the same quark action also being used for the valence quarks, including the charm. The spectrum is calculated for pion masses in the range $M_π\sim 259-460$ MeV at a lattice spacing $a\sim 0.075$ fm. Finite volume effects are studied comparing lattices with two different linear spatial extents ($1.8\,{\rm fm}$ and $2.4\,{\rm fm}$). The physical point is approached from the SU(3) limit keeping the flavour averaged light quark mass fixed. The baryon masses are extrapolated using expansions in the strange-light quark mass difference. Most particles fall into the expected SU(3) multiplets with well constrained extrapolations, the exceptions having a possibly more complex internal structure. Overall agreement is found with experiment for the masses and splittings of the singly charmed baryons. As part of the calculation an analysis of the lower lying charmonium, $D$ and $D_s$ spectra was performed in order to assess discretisation errors. The gross spectra are reproduced, including the $D^*_{s0}$, $D_{s1}$ and $D_1$ mesons, while at this single lattice spacing hyperfine splittings come out $10-20$ MeV too low.

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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