Speaker
Donghun Lee
(Yonsei University)
Description
We present the most systematic approach to discover a sterile neutrino $N$ or constrain $\left| U_{\ell N} \right|^2$, the mixing between active neutrino $\nu_\ell$ (with $\ell=\mu,\tau$) and the sterile neutrino $N$, from $B \to D\ell N$ decays. Our constraint on $\left| U_{\mu N} \right|^2$ achievable from Belle II data is comparable with that from the much larger data set of upgraded LHCb, even much better for mass of sterile neutrino $m_N < 2$~GeV. We can also probe the Dirac and Majorana nature of $N$ by observing the sequential decay of $N$, including suppression factors associated with observation of a displaced
vertex and helicity flip, for Majorana $N$.
