Discovery of a narrow resonance state of the system KSKS at mass 1520 MeV

Data are presented which indicate the existence of a previously unknown nar row resonance near mass 1520 MeV, discovered while analyzing the system KSK S. The data were obtained at ITEP using the 6-m magnetic spectrometer in a beam of 40-GeV negative particles. The resonance is observed in pi(-)p and K(-)p interactions with a total statistical confidence of not less than 5 s tandard deviations. The width of this state is comparable to the mass resol ution of the spectrometer (similar to 5 MeV). The mass is 1521.5 +/- 2.5 Me V. Estimates of the product sigma . BR(KSKS) give similar to 5.0 nb in pi(- )p interactions and similar to 250 nb in K(-)p interactions. From the fact that the production cross section of this resonance in the K- beam is appro ximately 50 times greater than the production cross section in the pi(-) be am, it can be concluded that this new state belongs to a system of mesons w ith hidden strangeness. (C) 1999 American Institute of Physics. [S0021-3640 (99)00316-3].