Study of the transverse mass spectra of strange particles in

The NA57 Collaboration: F Antinori, P Bacon, A Badalà, R Barbera, A Belogianni, A Bhasin, I J Bloodworth, M Bombara, G E Bruno †, S A Bull, R Caliandro, M Campbell, W Carena, N Carrer, R F Clarke, A Dainese, A P de Haas, P C de Rijke, D Di Bari, S Di Liberto, R Divià, D Elia, D Evans, G A Feofilov, R A Fini, P Ganoti, B Ghidini, G Grella, H Helstrup, K F Hetland, A K Holme, A Jacholkowski, G T Jones, P Jovanovic, A Jusko, R Kamermans, J B Kinson, K Knudson, A A Kolozhvari, V Kondratiev, I Králik, A Kravčáková, P Kuijer, V Lenti, R Lietava, G Løvhøiden, V Manzari, G Martinská, M A Mazzoni, F Meddi, A Michalon, M Morando, E Nappi, F Navach, P I Norman, A Palmeri, G S Pappalardo, B Pastirčák, J Pǐsút , N Pǐsútová , R J Platt, F Posa, E Quercigh, F Riggi, D Röhrich, G Romano, K Šafař́ık, L Šándor, E Schillings, G Segato, M Sené, R Sené, W Snoeys, F Soramel ‡, M Spyropoulou-Stassinaki, P Staroba, T A Toulina, R Turrisi, T S Tveter, J Urbán, F F Valiev, A van den Brink, P van de Ven, P Vande Vyvre, N van Eijndhoven, J van Hunen, A Vascotto, T Vik, O Villalobos Baillie, L Vinogradov, T Virgili, M F Votruba, J Vrláková and P Závada a Physics Department, University of Athens, Athens, Greece b Dipartimento IA di Fisica dell’Università e del Politecnico di Bari and INFN, Bari,