Comparative fits to identified-hadron spectra in relativistic p+p, p+Pb, Pb+Pb and Au+Au collisions including error covariances

Identified-hadron spectra derived from relativistic p+p, p+Pb, Pb+Pb, and Au+Au collisions have been extensively studied using a common fitting procedure. This approach incorporates published covariance information, where available, and applies dataset-dependent uncertainty approximations when necessary. The fitting models encompass Boltzmann–Gibbs, Tsallis, Lévy–Tsallis, blast-wave, Tsallis blast-wave, modified Hagedorn, and soft+hard variants.

A notable finding from the simultaneous heavy-ion fits is that the blast-wave description offers the most stable representation of the common low-\(p_T\) multi-species spectra. This trend is consistent across different collision centrality levels and yields consistent freeze-out temperatures and radial-flow patterns. However, the results for pPb and especially pp collisions exhibit greater model dependence, reduced stability in fits, and less secure parameter interpretation.

These findings underscore the strong freeze-out interpretation primarily in the heavy-ion multi-species sector. For smaller systems, the temperature and non-extensivity parameters are more appropriately viewed as model-dependent soft-sector scales rather than as reliable universal freeze-out indicators. The study was financially supported by Princess Nourah bint Abdulrahman University Researchers Supporting Project number PNURSP2026R106.

The research team acknowledges the contributions of the ALICE, CMS, and STAR Collaborations, as well as the accessibility of experimental spectra from HEPData. The funding agency explicitly stated that it had no influence over the study's design, data collection, analysis, interpretation, manuscript preparation, or the decision to publish.

The research was conducted by the Department of Physics at the University of Tabuk and Princess Nourah bint Abdulrahman University in Saudi Arabia. The findings are licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, permitting non-commercial use and distribution with appropriate attribution to the original authors and source.