Hadron spectra in p+p collisions at RHIC and LHC energies

TL;DR

This paper analyzes hadron transverse momentum spectra in proton-proton collisions at RHIC and LHC energies using Tsallis distributions, revealing energy-dependent trends in production parameters and suggesting a unified production mechanism at high energies.

Contribution

It demonstrates the successful application of Tsallis distribution to describe hadron spectra across multiple energies and identifies trends in the parameters indicating changes in production dynamics.

Findings

Tsallis temperature T decreases slightly with energy.

Parameter n decreases, indicating more point-like scatterings at higher energies.

Baryon and meson production processes converge at LHC energies.

Abstract

We present the systematic analysis of transverse momentum ($p_T$) spectra of identified hadrons in p+p collisions at RHIC ($\sqrt{s}$ = 62.4 and 200 GeV) and at LHC energies ($\sqrt{s}$ = 0.9, 2.76 and 7.0 TeV) using phenomenological fit functions. We review various forms of Hagedorn and Tsallis distributions and show their equivalence. We use Tsallis distribution which successfully describes the spectra in p+p collisions using two parameters, Tsallis temperature $T$ which governs the soft bulk spectra and power $n$ which determines the initial production in partonic collisions. We obtain these parameters for pions, kaons and protons as a function of center of mass energy ($\sqrt{s}$). It is found that the parameter $T$ has a weak but decreasing trend with increasing $\sqrt{s}$. The parameter $n$ decreases with increasing $\sqrt{s}$ which shows that production of hadrons at higher energies are increasingly dominated by point like qq scatterings. Another important observation is with increasing $\sqrt{s}$, the separation between the powers for protons and pions narrows down hinting that the baryons and mesons are governed by same production process as one moves to the highest LHC energy.