Observation Of F1 (1285) -]Pi+Pi-Pi+Pi-In Radiative J/Psi Decays

We present an analysis of J/psi --> gamma-f1 (1285), f1 (1285) --> pi+pi-pi+pi-, using the Mark III detector at SPEAR, based on 5.8 x 10(6) produced J/psi events. We measure B(J/psi --> gamma-f1 (1285), f1 (1285) --> pi+pi-pi+pi-) = (4.8 +/- 1.3 +/- 0.9) x 10(-5). We obtain a new measurement of the absolute branching ratio of J/psi --> gamma-f1 (1285). The mixing angle of the f1 (1285) and the f1 (1420) in the 1++ nonet is determined.