Looking for New Physics via Semi-leptonic and Leptonic rare decays of $D$ and $D_s$

Abstract

It is well recognized that looking for new physics at lower energy colliders is a tendency which is complementary to high energy machines such as LHC. Based on large database of BESIII, we may have a unique opportunity to do a good job. In this paper we calculate the branching ratios of semi-leptonic processes $D_s^{+}\to K^{+}{e}^{-}{e}^{+}$, $D_s^{+}\to K^{+}{e}^{-}{\mu }^{+}$ and leptonic processes $D^0\to e^{-}{e}^{+}$, $D^0\to e^{-}{\mu }^{+}$ in the frames of $U(1{)}^{\prime }$ model, 2HDM and unparticle separately. It is found that both the $U(1{)}^{\prime }$ and 2HDM may influence the semi-leptonic decay rates, but only the $U(1{)}^{\prime }$ offers substantial contributions to the pure leptonic decays and the resultant branching ratio of $D^0\to e^{-}{\mu }^{+}$ can be as large as $10^{-7}\sim 10^{-8}$ which might be observed at the future super $\tau$-charm factory.

Comments: 20 pages, 6 figures