Strong Coupling and Classicalization

TL;DR

Classicalization is a process where a theory avoids strong coupling by producing many soft quanta, leading to classical states at high energies, with implications for black hole formation and new resonances detectable at colliders.

Contribution

This paper explores classicalization as a mechanism beyond gravity, proposing it can solve the hierarchy problem and predict new resonances at high energies.

Findings

Classicalization prevents strong coupling by energy redistribution into soft quanta.

High-energy scattering results in classical states with high occupation numbers.

Predicted resonances could be observed at the LHC as short-lived particles.

Abstract

Classicalization is a phenomenon in which a theory prevents itself from entering into a strong-coupling regime, by redistributing the energy among many weakly-interacting soft quanta. In this way, the scattering process of some initial hard quanta splits into a large number of soft elementary processes. In short, the theory trades the strong coupling for a high-multiplicity of quanta. At very high energies, the outcome of such a scattering experiment is a production of soft states of high occupation number that are approximately classical. It is evident that black hole creation in particle collision at super-Planckian energies is a result of classicalization, but there is no a priory reason why this phenomenon must be limited to gravity. If the hierarchy problem is solved by classicalization, the LHC has a chance of detecting a tower of new resonances. The lowest-lying resonances must appear right at the strong coupling scale in form of short-lived elementary particles. The heavier members of the tower must behave more and more classically: they must be longer lived and decay into higher numbers of soft quanta.