Using the VENUS detector at TRISTAN we have investigated the charm-quark production by detecting D*+ - mesons in the two-photon process of e+et - collisions. The study has confirmed that the charm-quark production rate is larger than that predicted from direct cc̅ production alone. The distribution of the transverse momentum of the D*+ t- mesons and the forward energy flow associated with the D*+ - production suggest that the main part of the observed excess comes from the contribution of a resolved photon process.
D* production cross section in the given kinematic ranges under the anti-tagging condition |cos(theta(e+-))|>0.990.
The differential cross section of $d\sigma(e~+e~-\rightarrow e~+e~-D~{*\pm}X)/dP_T$ was measured using a soft-pion analysis of $D~{*\pm}\rightarrow \pi_s~\pm D~0(\overline{D~0})$ at TRISTAN. The average $\sqrt{s}$ was 58.1 GeV and the integrated luminosity used in this analysis was 198 pb$~{-1}$, respectively.
Soft pion cross section.
D*+- cross section from the soft-pion analysis.
Previous `full reconstruction' measurement from Enomoto et al. (to be published).