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arXiv 2310.04670hep-ph
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核子与重子八重态的力学结构:Twist-2 情形

Mechanical structure of the nucleon and the baryon octet: Twist-2 case

Ho-Yeon Won, Hyun-Chul Kim, June-Young Kim

AI总结:

本研究基于QCD大$N_c$极限的π介子平均场方法,分析核子与重子八重态引力形状因子的twist-2味分量贡献,揭示twist-4算符效应的关键作用,补充了对强子力学结构的认识。

摘要:

我们利用基于量子色动力学(QCD)大$N_c$极限的π介子平均场方法,研究了分解为味分量的核子与重子八重态的引力形状因子(GFFs)。我们重点关注twist-2算符对味三重态与八重态GFFs的贡献,并将核子的质量、角动量和$D$-项形状因子分解为各自的味分量。研究发现,奇异夸克对质量和角动量形状因子的贡献相对温和,但对$D$-项形状因子有显著修正。在检验GFFs味分解的过程中,我们发现twist-4算符的效应发挥着关键作用。在twist-2情形下,胶子贡献因瞬子真空的填充因子而被抑制,而twist-4算符的贡献量级为1,因此需要对其进行显式考虑。

英文摘要:

We investigate the gravitational form factors (GFFs) of the nucleon and the baryon octet, decomposed into their flavor components, utilizing a pion mean-field approach grounded in the large $N_c$ limit of Quantum Chromodynamics (QCD). Our focus is on the contributions from the twist-2 operators to the flavor-triplet and octet GFFs, and we decompose the mass, angular momentum, and $D$-term form factors of the nucleon into their respective flavors. The strange quark contributions are found to be relatively mild for the mass and angular momentum form factors, while providing significant corrections to the $D$-term form factor. In the course of examining the flavor decomposition of the GFFs, we uncover that the effects of twist-4 operators play a crucial role. While the gluonic contributions are suppressed by the packing fraction of the instanton vacuum in the twist-2 case, contributions from twist-4 operators are of order unity, necessitating its explicit consideration.

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