Hollowness in $pp$ and $p \bar p$ scattering in a Regge model

TL;DR

This paper demonstrates that a Regge model with specific pole structures predicts a hollow in the inelasticity profile at low impact parameters for both proton-proton and proton-antiproton collisions, challenging geometric inelasticity assumptions.

Contribution

It introduces a Regge-based theoretical model that accounts for hollowness in inelasticity profiles, linking amplitude ratios to collision character changes.

Findings

Hollowness occurs in both $pp$ and $p ar p$ collisions within the model.

The model challenges the applicability of geometric inelasticity-folding approaches.

Hollowness is sensitive to model details but remains a robust feature in the Regge framework.

Abstract

The proton-proton and proton-antiproton inelasticity profiles in the impact parameter display very interesting and sensitive features which cannot be deduced solely from the current large body of high-energy scattering data. In particular, phenomenological studies exhibit a link between the ratio of the real to imaginary parts of the elastic scattering amplitude at a finite momentum transfer, and the corresponding change of character of the inelastic processes from central to peripheral collisions. We describe how a theoretical model, accommodating the existing data, based on the Regge hypothesis including both the Pomeron and odderon as double poles, and $\omega$ and $f$ mesons as single poles in the complex-$J$ plane, generates a hollow in the inelasticity at low impact parameters. The hollowness effect, which generally may be sensitive to model details, does unequivocally take place both for $pp$ and $p \bar p$ collisions within the applied Regge framework, indicating inapplicability of inelasticity-folding geometric approaches.