Applications of Chiral Symmetry

Author: Davoudiasl, Hooman

Year: 1998

Degree: Dissertation (Ph.D.)

Advisor: Wise, Mark B.

Committee Member: Unknown, Unknown

Option: Physics

DOI: 10.7907/dv4e-6748

Abstract

We study some applications of the chiral symmetry of quantum chromodynamics in treating phenomena involving hadrons at low energies, where perturbative methods are not valid. We begin by introducing the concepts of global symmetry breaking and the consequent generation of Goldstone bosons. It is shown how these concepts are realized through chiral symmetry breaking and provide an understanding of some of the features of strong interactions at low energies. This leads us to the chiral perturbation theory effective Lagrangian for the low energy interactions of the light pseudo-scalars. We use this effective Lagrangian, and the considerations that led to it, as the basis of our approach in studying three different problems. First, we find the rates for the τ lepton decays τ → Vπvτ, where V stands for ρ, K* or w, and extract the magnitude of the ρwπ coupling, |g2(ρ)| = 0.6. Next, we use this coupling to find the decay rate for D0 → K*0π-e+Ve 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 finding solutions that represent the qualitative behavior of the disoriented chiral condensate in 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.

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