Review of the semiclassical formalism for multiparticle production at high energies

TL;DR

This paper reviews the semiclassical method for calculating multiparticle production rates at very high energies in scalar field theories, emphasizing non-perturbative approaches for large particle numbers.

Contribution

It provides a comprehensive overview of the semiclassical formalism applied to high-energy multiparticle production in scalar theories, highlighting its non-perturbative capabilities.

Findings

Semiclassical approach enables non-perturbative calculations of multiparticle rates.

Analysis focuses on high-energy limit with large particle numbers.

Method applicable to weakly-coupled scalar field theories.

Abstract

These notes provide a comprehensive review of the semiclassical approach for calculating multiparticle production rates for initial states with few particles at very high energies. In this work we concentrate on a scalar field theory with a mass gap. Specifically, we look at a weakly-coupled theory in the high-energy limit, where the number of particles in the final state scales with energy, $n\sim E\to \infty$, and the coupling $\lambda\to 0$ with $n \lambda$ held fixed. In this regime, the semiclasical approach allows us to calculate multiparticle rates non-perturbatively.