Speaker
Burkard Reisert
(MPI)
Description
The differential cross section for the process $\gamma \gamma \to \eta \pi^0$ has been measured in the kinematic range 0.84 GeV $< W <$ 4.0 GeV, $|\cos \theta^*| < 0.8$, where W and $\theta^*$ are the energy and $\pi^0$ (or $\eta$) scattering angle, respectively, in the $\gamma-\gamma$ center-of-mass system. The results are based on a 223 fb$^{-1}$ data sample collected with the Belle detector at the KEKB $e^+ e^-$ collider. Clear peaks due to the $a_0(980)$ and $a_2(1320)$ are visible. The differential cross sections are fitted in the energy region 0.9 GeV $< W <$ 1.46 GeV to obtain the parameters of the $a_0(980)$. The energy and angular dependences above 3.1 GeV are compared with those measured in the $\pi^0$ $\pi^0$ channel. The measured cross section ratio is consistent with QCD predictions. The $W^{-n}$ dependence of the integrated cross section has also been measured.
We also report a measurement of the exclusive cross section for $e^+ e^- \to D^0 D^{*-}\pi^+$ as a function of center-of-mass energy from the $D^0 D^{*-}\pi^+$ threshold to 5.2 GeV with initial-state radiation. The analysis is based on a data sample collected with the Belle detector at the $\Upsilon(4S)$ resonance and nearby continuum with an integrated luminosity of 695 fb$^{-1}$ at the KEKB asymmetric-energy $e^+ e^-$ collider.
The cross section s of the reactions $e^+ e^- \to \phi \eta$, $\phi \eta'$, $\rho \eta$, $\rho \eta'$ have been measured using a data sample of 516 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The energy dependence of the cross sections is presented using Belle measurements together with those of CLEO and BaBar.
Primary author
Burkard Reisert
(MPI)
