Study of $\pi^0$ pair production in single-tag two-photon collisions

摘要: We report a measurement of the differential cross section of π0 pair production in single-tag two-photon collisions, γ∗γ→π0π0, in e+e− scattering. The cross section is measured for Q2 up to 30 GeV2, where Q2 is the negative of the invariant mass squared of the tagged photon, in the kinematic range 0.5 GeV < W < 2.1 GeV and |cosθ∗| < 1.0 for the total energy and pion scattering angle, respectively, in the γ∗γ center-of-mass system. The results are based on a data sample of 759 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider. The transition form factor of the f0(980) and that of the f2(1270) with the helicity-0, -1, and -2 components separately are measured for the first time and are compared with theoretical calculations.