On the model-dependence of the relation between minimum-bias and inelastic proton–proton cross sections

S Ostapchenko

doi:10.1016/j.physletb.2011.08.050

Abstract

The model-dependence of the relation between the inelastic and various minimum-bias proton–proton cross sections is analyzed, paying a special attention to the sensitivity of minimum-bias triggers to diffractive collisions. Concentrating on the trigger selections of the ATLAS experiment, the measured cross sections are compared to predictions of a number of hadronic Monte Carlo models used in the cosmic ray field. It is demonstrated that the ATLAS results are able to discriminate between different models and between certain theoretical approaches for soft multi-particle production. On the other hand, the strong model-dependence of the selection efficiency of the minimum-bias triggers prevents one from inferring high mass diffraction rate from the discussed data. Moreover, the measured cross sections prove to be insensitive to the production of low mass diffractive states in proton–proton collisions. Consequently, a reliable determination of the total inelastic cross section requires forward proton tracking by a dedicated experiment.

Highlights

The knowledge of the inelastic proton–proton cross section and of its repartition into the non-diffractive one and into partial cross sections for various diffractive processes is of considerable importance for understanding the dynamics of strong interactions
A proper understanding of the energy-dependence of the inelastic and diffractive pp cross sections is of vital importance for experimental studies of high energy cosmic rays
Due to an extremely low incoming flux of such particles, their properties are inferred from measured characteristics of nuclearelectromagnetic cascades – extensive air showers induced by them in the air

Summary

Introduction

The knowledge of the inelastic proton–proton cross section and of its repartition into the non-diffractive one and into partial cross sections for various diffractive processes is of considerable importance for understanding the dynamics of strong interactions It is involved into determinations of collider luminosities and into normalizations of measured particle spectra. The longitudinal development of air showers depends strongly on the magnitude of σpinpel and on the relative rate of diffractive interactions [1] It has been proposed recently [2] that a study of minimumbias cross sections at the Large Hadron Collider (LHC) with various combinations of triggering detectors could be a powerful instrument for discriminating between theoretical approaches to hadronic multiple production and may allow one to infer the rate. We check if the ATLAS data are able to discriminate between different models of hadronic interactions, in particular, between the ones used to treat cosmic ray interactions in the atmosphere

Model approaches

Results for minimum-bias cross sections

Findings

Outlook