Speaker
Description
Many experiments are conducted to search for Dark Matter. In addition to the experiments detecting the Dark Matters through elastic scattering of nucleii, collider experiments can search for Dark Matter that are produced in the particle reactions.
We report the result of Belle experiment searching for Dark Photon ($A'$) in MeV region using a charmed decay.
The Belle experiment had been operated from 1999 to 2010 and the integrated luminosity is about 1 ab$^{-1}$. The high statistics sample can be utilized for the search of Dark Matter which is considered to be rarely produced.
Dark Photon, a part of Dark Matter model called Hidden Sector hypothesis, is predicted to have mixing with Standard Model photon. We use $D^{*0}\to D^0A'(\to e^+e^-)$ decay in data accumulated by Belle experiment that produces $c\bar{c}$ pair as well as $B\overline{B}$ meson pair. A process $D^{*0}\to D^0A'$ may occur by a mixing between $\gamma$ and $A'$ in $D^{*0}\to D^0\gamma$. The mass difference between $D^{*0}$ and $D^0$ is 142 MeV, so this is suitable to search for MeV scale Dark Photon.
In this presentation, we also review the recent searches for Dark Matter in $e^+e^-$ collider experiments; Belle, Belle2, and BaBar.
