Elastic scattering at 7 TeV and high energy cross section for cosmic ray studies

TL;DR

This paper examines proton-proton elastic scattering at 7 TeV using LHC data, testing a geometrical model's applicability to high-energy cosmic ray interactions and suggesting the need for model modifications at ultra-high energies.

Contribution

It evaluates the geometrical model of proton-proton scattering against recent LHC measurements and discusses necessary modifications for ultra-high-energy cosmic ray predictions.

Findings

Model describes lower energy data well with parameter adjustments.

Elastic differential cross section shape indicates a decreasing ratio of real to imaginary amplitude.

Proton-proton collision geometry likely needs significant revision at ultra-high energies.

Abstract

The recent measurements of the elastic cross section by the TOTEM Collaboration together with the first estimations of the inelastic cross sections by other LHC detectors are used to test the simplest version of the geometrical model of the proton-proton scattering. We show that the description found for lower energy data, with the modest adjustment of the model parameter extrapolation, could be, in principle, used to describe the LHC measurement and to predict the cross sections in very high energy cosmic ray domain. However, the shape of the first elastic dip in the elastic differential scattering cross section suggests that ratio of the real to the imaginary part of the elastic amplitude is falling rather fast and the analysis of the elastic cross section fraction suggests that the geometrical picture of the proton-proton collision should be modified considerably when entering the ultra high-energy domain.