Dynamical Pion Production via Parametric Resonance from Disoriented Chiral Condensate

TL;DR

This paper explores a mechanism for explosive pion production from disoriented chiral condensates via parametric resonance, drawing parallels with cosmological reheating, and analyzes quantum states and correlations of the produced pions.

Contribution

It introduces a detailed quantum description of pion production through parametric amplification in DCCs, including explicit quantum states and correlation functions.

Findings

Pion production is driven by parametric resonance similar to inflationary reheating.

Produced pions form squeezed states with distinctive back-to-back correlations.

Quantum analysis reveals characteristic multi-pion state features.

Abstract

We discuss a dynamical mechanism of pion production from disoriented chiral condensates (DCC). It leads to an explosive production of pions via the parametric amplification mechanism, which is similar to the reheating mechanism in inflationary cosmology. Classically, it is related with the instability in the solutions of the Mathieu equation and we explore the quantum aspects of the mechanism. We show that nonlinearlities and back reactions can be ignorable for sufficiently long time under the small amplitude approximations of background $\sigma$ oscillations, which may be appropriate for the late stage of nonequilibrium phase transition. It allows us to obtain an explicit quantum state of the produced pions and $\sigma$, the squeezed state of BCS type. Single particle distributions and two-pion correlation functions are computed within these approximations. The results obtained illuminate the characteristic features of multi-pion states produced through the parametric amplification mechanism. In particular, two-pion correlations of various charge combinations contain back-to-back correlations which cannot be masked by the identical particle interference effect.