Axial and electromagnetic observables of hyperons in 2-flavor chiral perturbation theory

F. -J. Jiang, B. C. Tiburzi, A. Walker-Loud

研究成果: 雜誌貢獻Conference article同行評審

摘要

Two-flavor chiral expansions provide a useful perturbative framework to study hadron properties. Such expansions should exhibit marked improvement over the conventional three-flavor chiral expansion. Although in principle one can formulate two-flavor theories for the various hyperon multiplets, the nearness of kaon thresholds can seriously undermine the effectiveness of such two-flavor theories in practice. We investigate the importance of virtual kaon thresholds on hyperon properties, specifically their isovector axial charges and electromagnetic observables. In particular we uncover the underlying expansion parameter governing the description of virtual kaon thresholds. For spin-half hyperons, this expansion parameter is under theoretical control. As a result, the virtual kaon contributions are well described in the two-flavor theory by terms analytic in the pion mass-squared. For spin three-half hyperons, however, one is closer to the kaon production threshold, and the expansion parameter is not as small. Breakdown of SU(2) chiral perturbation theory is shown to arise from a pole in the expansion parameter associated with the kaon threshold. We find that, despite the fact that higher-order corrections to the expansion parameter is necessary to ascertain whether the two-flavor theory of spin three-half hyperons remains perturbative, there is a useful perturbative expansion for isovector axial charges and magnetic moments of both spin-half and spin three-half hyperons.

原文英語
期刊Proceedings of Science
105
出版狀態已發佈 - 2010 一月 1
事件28th International Symposium on Lattice Field Theory, Lattice 2010 - Villasimius, Sardinia, 意大利
持續時間: 2010 六月 142010 六月 19

ASJC Scopus subject areas

  • General

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