Semiclassical Calculation of Multiparticle Scattering Cross Sections in Classicalizing Theories

TL;DR

This paper applies a semiclassical approach to analyze multiparticle scattering in classicalizing scalar theories, revealing a transition from exponential suppression to significant cross sections at high energies, supporting the classicalization concept.

Contribution

It demonstrates the applicability of semiclassical methods to the Dirac-Born-Infeld theory and identifies a critical particle number where scattering cross sections become sizable.

Findings

Cross section ceases to be exponentially suppressed above a critical particle number.

Critical particle number scales as (E L_*)^{4/3}.

Results support classicalization as a mechanism for unitarity restoration.

Abstract

It has been suggested in arXiv:1010.1415 that certain derivatively coupled non-renormalizable scalar field theories might restore the perturbative unitarity of high energy hard scatterings by classicalization, i.e. formation of multiparticle states of soft quanta. Here we apply the semiclassical method of calculating the multiparticle production rates to the scalar Dirac-Born-Infeld (DBI) theory which is suggested to classicalize. We find that the semiclassical method is applicable for the energies in the final state above the cutoff scale of the theory L_*^{-1}. We encounter that the cross section of the process two to N ceases to be exponentially suppressed for the particle number in the final state N smaller than a critical particle number N_{crit} ~ (E L_*)^{4/3}. It coincides with the typical particle number produced in two-particle collisions at high energies predicted by classicalization arguments.