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arXiv 0908.2582nucl-thhep-lathep-ph
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超子的双味手征微扰理论

Two-Flavor Chiral Perturbation Theory for Hyperons

B. C. Tiburzi

摘要:

八重态重子的三味手征展开有着众所周知的收敛问题。我们表明,这三味手征性膨胀可以重组成一个两味膨胀,从而消除大的K介子和η循环的贡献。通过考虑奇异性变化阈值对超子质量的影响,解决了基础配方的问题。虽然自旋-3/2超子共振比自旋-1/2超子共振对这些阈值更敏感,但我们证明了在这两种情况下,基本物理可以在双味有效理论中被解析的π质量平方项捕获,但在奇异夸克质量中是非解析的。利用超子的双味理论,研究了重子质量和轴荷。在双味理论中,回路的贡献似乎受到微扰的控制。一个自然的应用,我们的发展是研究介子质量的格点量子色动力学数据对超子性质的依赖。

英文摘要:

The three-flavor chiral expansion for octet baryons has well-known problems with convergence. We show that this three-flavor chiral expansion can be reorganized into a two-flavor expansion thereby eliminating large kaon and eta loop contributions. Issues of the underlying formulation are addressed by considering the effect of strangeness changing thresholds on hyperon masses. While the spin-3/2 hyperon resonances are considerably more sensitive to these thresholds compared to the spin-1/2 hyperons, we demonstrate that in both cases the essential physics can be captured in the two-flavor effective theory by terms that are analytic in the pion mass squared, but non-analytic in the strange quark mass. Using the two-flavor theory of hyperons, baryon masses and axial charges are investigated. Loop contributions in the two-flavor theory appear to be perturbatively under control. A natural application for our development is to study the pion mass dependence of lattice QCD data on hyperon properties.

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