Da. Bauer et al., EVIDENCE FOR SPIN-ONE RESONANCE PRODUCTION IN THE REACTION GAMMA-GAMMA-ASTERISK-]PI-PI-0-PI-0(PI), Physical review. D. Particles and fields, 48(9), 1993, pp. 3976-3986
Using data from the TPC/Two-Gamma experiment at the SLAC e+e- storage
ring PEP, a C = +1 resonance has been observed in the pi+pi-pi0gamma f
inal state resulting from the fusion on one nearly real and one quite
virtual photon. The actual decay channel is probably pi+pi-pi0pi0, whe
re one final-state photon is not detected, and the mass of the fully r
econstructed state would be approximately 1525 MeV. A four-pion decay
mode in turn implies that the resonance has even isospin. The nonobser
vation of this R (1525) when both initial-state photons are nearly rea
l suggests a spin-1 assignment. Since the large measured value of the
product of the branching ratio into pi+pi-pi0pi0 and the gammagamma co
upling makes it unlikely that this state is the mostly ssBAR f1(1510),
its interpretation may lie outside of conventional meson spectroscopy
. There is a second, less-significant enhancement observed in the same
reaction at a four-pion mass centered around 2020 MeV.