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Effective QCD string and doubly heavy baryons
Physical Review D ( IF 4.6 ) Pub Date : 2021-10-22 , DOI: 10.1103/physrevd.104.074027
Joan Soto 1 , Jaume Tarrús Castellà 2
Affiliation  

Expressions for the potentials appearing in the nonrelativistic effective field theory description of doubly heavy baryons are known in terms of operator insertions in the Wilson loop. However, their evaluation requires nonperturbative techniques, such as lattice QCD, and the relevant calculations are often not available. We propose a parametrization of these potentials with a minimal model dependence based on an interpolation of the short- and long-distance descriptions. The short-distance description is obtained from weakly-coupled potential NRQCD and the long-distance one is computed using an effective string theory. The effective string theory coincides with the one for pure gluodynamics with the addition of a fermion field constrained to move on the string. We compute the hyperfine contributions to the doubly heavy baryon spectrum. The unknown parameters are obtained from heavy quark-diquark symmetry or fitted to the available lattice-QCD determinations of the hyperfine splittings. Using these parameters we compute the double charm and bottom baryon spectrum including the hyperfine contributions. We compare our results with those of other approaches and find that our results are closer to lattice-QCD determinations, in particular for the excited states. Furthermore, we compute the vacuum energy in the effective string theory and show that the fermion field contribution produces the running of the string tension and a change of sign in the Lüscher term.

中文翻译:

有效的 QCD 弦和双重重子

出现在双重重子的非相对论有效场论描述中的势的表达式根据威尔逊环中的算子插入是已知的。然而,他们的评估需要非微扰技术,例如格子 QCD,并且相关计算通常不可用。我们提出了基于短距离和长距离描述的插值的具有最小模型依赖性的这些潜力的参数化。短距离描述是从弱耦合势 NRQCD 获得的,长距离描述是使用有效弦理论计算的。有效弦理论与纯胶动力学的理论相吻合,其中添加了一个限制在弦上移动的费米子场。我们计算对双重重子谱的超精细贡献。未知参数是从重夸克-双夸克对称性中获得的,或者拟合到可用的超精细分裂的晶格-QCD 测定中。使用这些参数,我们计算双重魅力和底部重子谱,包括超精细贡献。我们将我们的结果与其他方法的结果进行比较,发现我们的结果更接近于晶格 QCD 测定,特别是对于激发态。此外,我们计算了有效弦理论中的真空能量,并表明费米子场的贡献会产生弦张力的运行和 Lüscher 项的符号变化。使用这些参数,我们计算双重魅力和底部重子谱,包括超精细贡献。我们将我们的结果与其他方法的结果进行比较,发现我们的结果更接近于晶格 QCD 测定,特别是对于激发态。此外,我们计算了有效弦理论中的真空能量,并表明费米子场的贡献产生了弦张力的运行和 Lüscher 项的符号变化。使用这些参数,我们计算双重魅力和底部重子谱,包括超精细贡献。我们将我们的结果与其他方法的结果进行比较,发现我们的结果更接近于晶格 QCD 测定,特别是对于激发态。此外,我们计算了有效弦理论中的真空能量,并表明费米子场的贡献会产生弦张力的运行和 Lüscher 项的符号变化。
更新日期:2021-10-22
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