Baryon Transverse Momentum Distributions at LHC and the "Knee" in Cosmic Proton Spectrum

TL;DR

This paper analyzes high-energy baryon transverse momentum spectra from LHC data using the Quark-Gluon String Model, showing a universal energy dependence that impacts understanding of the cosmic ray 'knee' and galactic proton energies.

Contribution

It demonstrates that the energy dependence of baryon transverse momentum spectra follows a universal pattern, challenging previous interpretations of the cosmic ray 'knee' as a change in hadroproduction dynamics.

Findings

Energy dependence of <Pt> follows s^0.12 asymptotics.

The cosmic ray 'knee' is not due to hadroproduction changes.

Maximum galactic proton energy may be indicated.

Abstract

The transverse momentum spectra of hyperons from LHC experiments (ALICE, ATLAS, CMS) are considered from the point of view of Quark-Gluon String Model (QGSM) as examples of typical baryon spectra at very high energies. The LHC data at \sqrt{s} = 0.9 and 7 TeV and STAR data at \sqrt{s} = 200 GeV are fitted with the universal QGSM formula that includes the energy dependent slope as the main parameter. The dependence of <Pt> on the collision energy has been obtained with the help of this formula. The asymptotics of the energy dependence of average transverse momenta shows the expected pomeronic behavior ~ s^0,12. This conclusion is very important for cosmic ray physics. It means that the long debated "knee" in the cosmic proton spectra at E_p= 4 10^15 eV in laboratory system can not be considered any more as the result of dramatic changes in the dynamics of baryon hadroproduction. In the same time it may indicate the maximal energy of protons that are being produced in our Galaxy. This last conclusion depends on the hadroproduction model.