Tsallis Fits to pT Spectra and Multiple Hard Scattering in pp Collisions at the LHC

TL;DR

This paper explores whether the Tsallis distribution's parameters in high-energy pp collision spectra can be explained by underlying relativistic parton scattering and related processes, analyzing their impact on observed power-law behaviors.

Contribution

It investigates the origin of Tsallis parameters from parton hard-scattering and showering processes, linking phenomenological fits to fundamental QCD mechanisms.

Findings

Hadron spectra follow a power-law with n > 4 at high pT.

Jet spectra exhibit a power-law with n ~ 4-5.

Power indices differ systematically between hadrons and jets.

Abstract

Phenomenological Tsallis fits to the CMS, ATLAS, and ALICE transverse momentum spectra of hadrons for pp collisions at LHC were recently found to extend over a large range of the transverse momentum. We investigate whether the few degrees of freedom in the Tsallis parametrization may arise from the relativistic parton-parton hard-scattering and related processes. The effects of the multiple hard-scattering and parton showering processes on the power law are discussed. We find empirically that whereas the transverse spectra of both hadrons and jets exhibit power-law behavior of 1/pT^n at high pT, the power indices n for hadrons are systematically greater than those for jets, for which n~4-5.