ISSN:
1434-6052
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract. Due to its light mass, of order $\Lambda_{\mathrm {QCD}}$ , the strange quark can play a special role in chiral symmetry breaking ( $\chi$ SB): differences in the pattern of $\chi$ SB in the limits N f = 2 ( $m_u,m_d\to 0$ , m s physical) and N f = 3 ( $m_u,m_d,m_s\to 0$ ) may arise due to vacuum fluctuations of $s\bar{s}$ pairs, related to the violation of the Zweig rule in the scalar sector and encoded in particular in the O(p 4) low-energy constants L 4 and L 6. In case of large fluctuations, we show that the customary treatment of SU(3) x SU(3) chiral expansions generates instabilities upsetting their convergence. We develop a systematic program to cure these instabilities by resumming non-perturbatively vacuum fluctuations of $s\bar{s}$ pairs, in order to extract information about $\chi$ SB from experimental observations even in the presence of large fluctuations. We advocate a Bayesian framework for treating the uncertainties due to the higher orders. As an application, we present a three-flavor analysis of the low-energy $\pi\pi$ scattering and show that the recent experimental data imply a lower bound on the quark mass ratio $2m_s/(m_u + m_d)\geq 14$ at 95% confidence level. We outline how additional information may be incorporated to further constrain the pattern of $\chi$ SB in the N f = 3 chiral limit.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1140/epjc/s2004-01601-4
Permalink