We have measured the cross section for π + π − production in two-photon collisions using a data sample with an integrated luminosity of 85.9 fb −1 collected with the Belle detector. The f0(980) resonance is observed as a peak in the energy spectrum of the cross section. We also report preliminary results for γγ → π 0 π 0 with two-photon center-of-mass energies ranging from 0.6 to 4.0 GeV, based on a 95 fb −1 data sample. We find at least four resonant structures including a peak from f0(980). In addition, there is evidence for χc0 production. We also make a preliminary discussion of the angular dependence and cross section ratio of γγ → π + π − and γγ → π 0 π 0 .
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.