Scaling laws for softened hadron production at LHC energies

TL;DR

This study analyzes soft hadron production at LHC energies, revealing universal scaling laws and differences between small and large collision systems, emphasizing the role of freeze-out parameters.

Contribution

It introduces a data-driven scaling law framework for softened hadron production across different collision systems at LHC energies.

Findings

Soft hadron contributions follow universal scaling laws.

Different relations between temperature, multiplicity, and average pT in pp and AA collisions.

Production mechanisms are similar across systems, mainly influenced by freeze-out parameters.

Abstract

In this paper, we conduct a data-driven study of the production of softened hadrons and their contribution to the transverse momentum spectrum. To this end, we assume that the production of charged particles at soft and hard scales fundamentally results from the fragmentation of color strings. We analyze the $p_\text{T}$-spectrum data from pp to AA collisions at LHC energies reported by the ALICE Collaboration, finding that, in all cases, the data can be collapsed into a $p_\text{T}$-exponential trend in the range 1 GeV$<p_\text{T}<$6 GeV. With this insight, the description of the $p_\text{T}$-spectrum should contain information on the charged particle production coming from two different sources: fragmentation of color strings and collective phenomena that redistribute the transverse momentum and enhance the production of particles at intermediate $p_\text{T}$. We also found different relations between the effective temperature, multiplicity, and average $p_\text{T}$ for pp and AA collisions, indicating inherent dissimilarities between small and large colliding systems. In contrast, the contribution of the softened hadrons to the $p_\text{T}$-spectrum and average $p_\text{T}$ collapse onto scaling laws. Our results show that the physical mechanisms producing softened hadrons have similar origins for all colliding systems, revealing a stronger dependence on freeze-out parameters rather than the system size.