Centrality and participant-number systematics of two-component standard-distribution parameters for identified hadrons in Au + Au collisions at sNN=77–624 GeV

Transverse-momentum ([Formula: see text]) spectra of identified hadrons are a powerful and precise phenomenological tool to study the collision-energy, centrality, and particle-species dependence of the matter created in relativistic heavy-ion collisions. We report a systematic study of [Formula: see text], [Formula: see text], p and [Formula: see text] production in Au[Formula: see text][Formula: see text][Formula: see text]Au collisions as a function of the RHIC Beam Energy Scan (BES) range of [Formula: see text]–62.4[Formula: see text]GeV. The component inverse-slope parameters (effective temperature-like) [Formula: see text] and [Formula: see text], the fractional contribution k, the weighted effective temperature-like parameter T, the mean transverse momentum [Formula: see text], the model-derived source-temperature parameter [Formula: see text], and the free normalization parameter [Formula: see text] are extracted and/or calculated within a two-component standard distribution, together with the fit-quality measure [Formula: see text]. The results are presented according to centrality, [Formula: see text] and [Formula: see text]. For the particle species available, T, [Formula: see text] and [Formula: see text] drop from central to peripheral collisions and rise with [Formula: see text], indicating systematic spectral softening towards the smaller collision systems. Saturation-like behavior is observed as a descriptive pattern in both the energy scan and the centrality scan: from an energy of about [Formula: see text][Formula: see text]GeV and upwards, the growth of T, [Formula: see text] and [Formula: see text] weakens, and the centrality interval, where the parameters are nearly saturated, moves towards more peripheral collisions as the energy of the collisions increases. The extracted parameters exhibit a clear mass ordering at fixed energy and centrality with proton/antiproton values larger than kaon values that in turn are larger than pion values. The contribution is the combined energy–centrality systematics of spectral hardness, rather than a new thermodynamic interpretation of the fitted parameters.

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