Estimation of Hydrodynamical Model Parameters from the Invariant Spectrum and the Bose-Einstein Correlations of pi-mesons Produced in (pi+/K+)p Interactions at 250 GeV/c

TL;DR

This paper analyzes pi-meson spectra from high-energy pion and kaon interactions with protons using a hydrodynamical model, extracting parameters like temperature, expansion velocities, and source size, consistent with experimental data.

Contribution

It introduces a detailed hydrodynamical model fit to experimental spectra, revealing the expansion dynamics and freeze-out conditions of the hadronic matter in high-energy collisions.

Findings

Longitudinal expansion dominates over transverse expansion.

Extracted freeze-out temperature varies transversely, indicating inhomogeneity.

Estimated source size and freeze-out time are consistent with Bose-Einstein correlations.

Abstract

The invariant spectra of pi- mesons produced in (pi+/K+)p interactions at 250 GeV/c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically symmetric finite systems. A satisfactory description of experimental data is achieved. The data favour the pattern according to which the hadron matter undergoes predominantly longitudinal expansion and non-relativistic transverse expansion with mean transverse velocity <u_t> = 0.20(7), and is characterized by a large temperature inhomogeneity in the transverse direction: the extracted freeze-out temperature at the center of the tube and at the transverse rms radius are 140(3) MeV and 82(7) MeV, respectively. The width of the (longitudinal) space-time rapidity distribution of the pion source is found to be Delta eta = 1.36(2). Combining this estimate with results of the Bose-Einstein correlation analysis in the same experiment, one extracts a mean freeze-out time of the source of <tau_f> = 1.4(1) fm/c and its transverse geometrical rms radius, R_G (rms)=1.2(2) fm.