Thermal analysis of production of resonances in relativistic heavy-ion collisions

Abstract

Production of resonances is considered in the framework of the single-freeze-out model of ultra-relativistic heavy ion collisions. The formalism involves the virial expansion, where the probability to form a resonance in a two-body channel is proportional to the derivative of the phase-shift with respect to the invariant mass. The thermal model incorporates longitudinal and transverse flow, as well as kinematic cuts of the STAR experiment at RHIC. We find that the shape of the pi+ pi- spectral line qualitatively reproduces the preliminary experimental data when the position of the rho peak is lowered. This confirms the need to include the medium effects in the description of the RHIC data. We also analyze the transverse-momentum spectra of rho, K*(892), and f_0(980), and find that the slopes agree with the observed values. Predictions are made for eta, eta', omega, phi, Lambda(1520), and Sigma(1385).