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

Identified-hadron spectra are widely used to extract the kinetic freeze-out temperature and collective radial flow. The extracted parameters depend on the fit model, the treatment of uncertainties, and the hadron species included in the fit. We analyze spectra from ALICE, CMS, and STAR in pp, pPb, PbPb, and AuAu collisions with a common fitting procedure that uses published covariance information where available and applies explicit dataset-dependent uncertainty approximations otherwise. The fitted forms include Boltzmann–Gibbs, Tsallis, Lévy–Tsallis, blast-wave, Tsallis blast-wave, modified Hagedorn, and soft+hard variants. The clearest result comes from the simultaneous heavy-ion fits. In AuAu and in most PbPb classes, the blast-wave description gives the most stable account of the common low- \(p_T\) multi-species spectra, with consistent freeze-out temperatures and radial-flow trends across centrality. The corresponding extraction in pPb, and especially in pp, is more model dependent, has weaker fit stability, and gives less secure parameter interpretation. The results support a freeze-out interpretation most strongly in the heavy-ion multi-species sector. In small systems, the temperature and non-extensivity parameters are better interpreted as model-dependent soft-sector scales than as robust universal freeze-out measures.