Applications of Chiral Symmetry

[摘要] We study some applications of the chiral symmetry of quantum chromodynamics intreating phenomena involving hadrons at low energies, where perturbative methodsare not valid. We begin by introducing the concepts of global symmetry breakingand the consequent generation of Goldstone bosons. It is shown how these conceptsare realized through chiral symmetry breaking and provide an understanding of someof the features of strong interactions at low energies. This leads us to the chiralperturbation theory effective Lagrangian for the low energy interactions of the lightpseudo-scalars. We use this effective Lagrangian, and the considerations that led toit, as the basis of our approach in studying three different problems. First, we findthe rates for the τ lepton decays τ → Vπv_τ, where V stands for ρ, K* or w, andextract the magnitude of the ρwπ coupling, |g2^(ρ)| = 0.6. Next, we use this couplingto find the decay rate for D⁰ → K*⁰π^-e⁺V_e in a certain kinematic regime. This rate depends on the DD^*π coupling and our results can provide and extraction of this coupling, given data on this decay. The third problem we address is that of findingsolutions that represent the qualitative behavior of the disoriented chiral condensatein the non-linear sigma model O(p⁴). We show that these solutions do not become singular at short distances where the O(p²) solutions begin to diverge.

[发布机构] University:California Institute of Technology;Department:Physics, Mathematics and Astronomy

[关键词] Physics