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

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.