# Transverse momentum spectra of hadrons in high energy pp and heavy ion collisions

## TL;DR

This study analyzes transverse momentum spectra of hadrons in high-energy proton-proton and heavy-ion collisions using Tsallis/Hagedorn functions, revealing energy dependence and deviations due to flow and energy loss effects.

## Contribution

It introduces modifications to the Tsallis/Hagedorn model to account for flow and energy loss, improving the description of spectra across different collision systems.

## Key findings

- Tsallis/Hagedorn function fits spectra from 0.2 to 300 GeV/c
- Power index n varies with collision energy as a+b/√s
- Deviations increase with system size and are linked to flow and energy loss

## Abstract

We present a study of transverse momentum ($p_{T}$) spectra of unidentified charged particles in pp collisions at RHIC and LHC energies from $\sqrt{s}$ = 62.4 GeV to 13 TeV using Tsallis/Hagedorn function. The power law of Tsallis/Hagedorn form gives excellent description of the hadron spectra in $p_{T}$ range from 0.2 to 300 GeV/$c$. The power index $n$ of the $p_T$ distributions is found to follow a function of the type $a+b/\sqrt {s}$ with asymptotic value $a = 5.72$. The parameter $T$ governing the soft bulk contribution to the spectra remains almost same over wide range of collision energies. We also provide a Tsallis/Hagedorn fit to the $p_{T}$ spectra of hadrons in pPb and different centralities of PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. The data/fit shows deviations from the Tsallis distribution which become more pronounced as the system size increases. We suggest simple modifications in the Tsallis/Hagedorn power law function and show that the above deviations can be attributed to the transverse flow in low $p_T$ region and to the in-medium energy loss in high $p_T$ region.