Belle II studies of missing energy decays and searches for dark photon production

Understand

The Belle II experiment at the SuperKEKB collider is a major upgrade of the KEK "$B$ factory" facility in Tsukuba, Japan.

• The machine is designed for an instantaneous luminosity of $8\times 10^{35}$~cm$^{-2}$\,s$^{-1}$, and the experiment is expected to accumulate a data sample of about 50 ab$^{-1}$ well within the next decade.
• With this amount of data, decays sensitive to physics beyond the Standard Model can be studied with unprecedented precision.
• One promising set of modes are physics processes with missing energy such as $B^+\to\tau^+\nu_{\tau}$, $B\to D^{(*)}\tau\nu_{\tau}$, and $B\to K^{(*)}\nu\bar\nu$ decays.