2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/48991The evidence for the low mass J^{PC}=0^{++} states is reconsidered. We suggest classifying the isoscalars f_0(980) and f_0(1500) as members of the 0^{++} nonet, with a mixing rather similar to that of the pseudoscalars η' and η. The broad state called f_0(400-1200) or `sigma'' and the state f_0(1370) are considered as different signals from a single broad resonance, which we take to be the lowest-lying 0^{++} glueball. The main arguments in favor of these hypotheses are presented and compared with theoretical expectations.Talk at the Workshop on Hadron Spectroscopy (W.O.), Frascati, Italy, March 8-12th, 1999, to be published in Frascati Physics Series, 11 pages, 3 figures, LATEXHigh Energy Physics - Phenomenologytext