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arXiv 1009.2170hep-ph
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手征微扰理论中的同位旋破缺夸克凝聚

Isospin-Breaking quark condensates in Chiral Perturbation Theory

A. Gomez Nicola, R. Torres Andres

摘要:

本文在单圈SU(2)和SU(3)手征微扰理论中,分析了夸克凝聚的同位旋破缺修正,包括$m_u\neq m_d$和电磁场的贡献。给出了显式表达式,并研究了几个唯象问题。我们分析了最近的凝聚测定EM低能常数(LEC)的灵敏度。如果由电磁项引起的明确的手征对称性破缺产生了真空的类铁磁响应,如夸克质量的情况下,序参量的增加意味着对电磁LEC的约束,我们检查与文献中的不同估计。此外,我们扩展了SU(3)中与夸克凝聚比相关的求和规则,使之包括EM修正,这与$m_u\neq m_d$的阶数相同,我们使用该求和规则来估计ChPT中的真空不对称性。我们还讨论了在同时考虑两个同位旋破缺源的情况下,凝聚体中SU(2)和SU(3)LEC之间的匹配条件。

英文摘要:

We analyze the isospin-breaking corrections to quark condensates within one-loop SU(2) and SU(3) Chiral Perturbation Theory including $m_u\neq m_d$ as well as electromagnetic (EM) contributions. The explicit expressions are given and several phenomenological aspects are studied. We analyze the sensitivity of recent condensate determinations to the EM low-energy constants (LEC). If the explicit chiral symmetry breaking induced by EM terms generates a ferromagnetic-like response of the vacuum, as in the case of quark masses, the increasing of the order parameter implies constraints for the EM LEC, which we check with different estimates in the literature. In addition, we extend the sum rule relating quark condensate ratios in SU(3) to include EM corrections, which are of the same order as the $m_u\neq m_d$ ones, and we use that sum rule to estimate the vacuum asymmetry within ChPT. We also discuss the matching conditions between the SU(2) and SU(3) LEC involved in the condensates, when both isospin-breaking sources are taken into account.

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