Search for $CP$ violation in $D$ decays to radiative and hadronic decays and search for rare $D$ decay at Belle

Abstract

Using the large data sample accumulated by the Belle experiment at KEKB asymmetry energy $e^+e^-$ Collider, we report the preliminary measurements of the branching fractions of the radiative decays $D^0 \rightarrow Vγ$, where $V$ = $ϕ,\bar{K^*}^0, ρ^0$. This is the first observation of the decay $D^0 \rightarrow ρ^0γ$ and also present the preliminary results of the first measurement of $CP$ asymmetry in these decays. We present the preliminary result of the $CP$ asymmetry of the $D^0 \rightarrow K^0_S K^0_S$ decay, which is consistent with no $CP$ violation and improves the uncertainty with respect to the previous measurement of this quantity by more than a factor of three. Finally, we present the results of the rare charm decay $D^0 \rightarrow γγ$, resulting in the most restrictive upper limit to date.

6 pages, 5 figures, ICHEP 2016