Statistical hadron-gas treatment of systems created in proton-proton interactions at energies available at the CERN Super Proton Synchrotron

Abstract

We analyze the newest data from the NA61/SHINE collaboration which, in addition to previous results on pions and kaons, include mean multiplicities of p, Λ, and φ-mesons produced in inelastic proton-proton (p+p) interactions at √ s N N = 6.3 − 17.3 GeV. The canonical ensemble formulation of the ideal hadron resonance gas (HRG) model is used with exact conservation of net baryon number B = 2, electric charge Q = 2, and strangeness S = 0. The chemical freeze-out parameters in p+p interactions are obtained and compared to those in central nucleus-nucleus collisions. Several features of p+p interactions at the CERN SPS within a statistical model are studied: 1) the inclusion of the φ-meson yields in thermal fits worsens significantly the fit quality; 2) the data show large event-by-event multiplicity fluctuations in inelastic p+p interactions which can not be explained by a single fireball described by a statistical model; 3) the fits within the canonical ensemble formulation of HRG do not give any improvement over the fits within the grand canonical ensemble formulation, i.e., there are no indications for existence of a single statistical system in p+p inelastic interactions in the considered energy range. PACS numbers: 25.75.-q, 25.75.Dw, 24.10.Pa

Thermal-FIST: A package for heavy-ion collisions and hadronic equation of state

“…Treatment of probabilistic decays [39] and hadronic interactions [36] is important in such applications, and it is included into the Thermal-FIST package. The applications of the Thermal-FIST package which can be found in the literature include chemical freeze-out analysis in proton-proton [40,41] and nucleus-nucleus collisions [42][43][44], influence of the EV interactions on thermal fits [27,[45][46][47] and equation of state [32,33,48,49], Monte Carlo analysis of EV effects in the canonical ensemble [50], effects of the vdW interactions between baryons and nuclear liquid-gas transition on various observables [29,30,[51][52][53], and thermal production of light nuclei [54,55].…”

$$K^{*}(892)^0$$ meson production in inelastic p+p interactions at 158 $$\text{ Ge }\text{ V }\!/\!c$$ beam momentum measured by NA61/SHINEat the CERN SPS

“…In the following the measured K * (892) 0 multiplicities are compared with predictions of two HGM models described in Refs. [41,42]. In Ref.…”

“…Note that the centrality of Pb+Pb collisions used in the HGM fits was 0-5% whereas the K * (892) 0 values in NA49 were obtained for the 0-23.5% most central interactions. Therefore, the HGM yields had to be scaled by a factor 262/362 [42,43]. N W denotes the number of wounded nucleons taken from Ref.…”

“…The p+p measurements are very close to the HGM prediction but only in case of fit A, where the φ meson was excluded from the fit. In the most recent paper [42], where the HGM fits were done for the NA49 and the new NA61/SHINE measurement in p+p interactions, it is also stressed that at SPS energies the φ meson multiplicities in p+p collisions cannot be well fitted within the CE formulation of the HGM (the quality of CE fits becomes much worse when the φ meson yield is included). However, the mean multiplicity of K * (892) 0 mesons in inelastic p+p collisions at 158 GeV/c can also be compared to the HGM prediction based on the Grand Canonical Ensemble formulation [42].…”

“…The mean multiplicity of K * (892) 0 mesons for 158 GeV/c inelastic p+p interactions compared to theoretical multiplicities obtained within Hadron Gas Models[41,42] …”