We report a measurement of differential cross section of $\pi^{ 0}$ pair production in single-tag two-photon collisions. These results are obtained with 759$fb^{ -1}$ of the data collected with the Belle detector at the KEKB asymmetric energy $e^{ +}e^{ -}$ collider. The cross section is measured for $Q^{ 2}$ up to 30 GeV$^{ 2}$, where $Q^{ 2}$ is the negative of the invariant mass squared of the tagged virtual photon, in the kinematic range 0.5 GeV < $W$ < 2.1 GeV and |cos$\theta^{ *}$| < 1.0 for the total energy and pion scattering angle, respectively. The transition form factor of the $f_{ 0}(980)$ and that of the $f_{ 2}(1270)$ with the helicity-0,-1, and -2 components separately are measured for the first time and are compared with theoretical calculations.
Categories: hep-ex