Transverse mass spectra of strange and multi–strange particles in Pb–Pb collisions at 158 A GeV/c

Abstract.

The WA97 experiment has measured the transverse mass $({m_{\mathrm T}})$ spectra for negative hadrons ($\mathrm{h}^-$) and strange particles produced at mid–rapidity in Pb–Pb collisions. The increased statistics of analysed data samples allowed us to perform a study of the spectra of ${\rm K_S^0}$, $\mathrm{\Lambda}$, $\mathrm{\Xi}$, $\mathrm{\Omega}$ and $\mathrm{h}^-$ as a function of the collision centrality. The data, which correspond to the most central 40% of the total inelastic cross section, have been divided into four centrality classes according to the estimated number of nucleons taking part in the collision. The $m_{\mathrm T}$ spectra, analysed separately for each centrality bin, exhibit only weak ($\leq$ 15%) centrality dependence. The deviation of the $\mathrm{\Omega}$ inverse slope from the linear dependence on the particle mass is confirmed even for the most central Pb–Pb collisions.