Fine structure of the diffraction cone: manifestation of t channel unitarity

TL;DR

This paper explains the deviation from exponential behavior in the diffraction cone at high energies as a consequence of a two-pion loop in the t channel, consistent with unitarity, using a Regge-pole model.

Contribution

It demonstrates that the diffraction cone 'break' near t=-0.1 GeV^2 is caused by a two-pion loop in the t channel, extending the understanding from ISR to LHC energies.

Findings

The 'break' is explained by a two-pion loop in the t channel.

The model successfully extrapolates the 'break' from ISR to LHC energies.

Unitarity constraints are key to understanding diffraction cone deviations.

Abstract

We show that the deviation from exponential behavior of the diffraction cone observed near t=-0.1 GeV^2 both at ISR and the LHC (so-called break) follows from a two-pion loop in the t channel, imposed by unitarity. By using a simple Regge-pole model, we extrapolate the "break" from the ISR energy region to that of the LHC.