Scalar mesons in weak semileptonic decays of $B_{(s)}$

Abstract

The transition form factors of $B_{(s)}\to S$, with $S$ denoting a scalar meson, are investigated in the light-cone sum rules approach. The numerical values are approximately twice as large as that estimated in the light-front quark model and QCD sum rules approach. Using these form factors, we present the analysis of the decay rates for $B\to a_0(1450)l{\bar{\nu }}_l$, $B\to K_0^{\ast }(1430)l\bar{l}$, $B_s\to K_0^{\ast }(1430)l{\bar{\nu }}_l$ and $B_s\to f_0(1500)l\bar{l}$ with $l=e,\mu ,\tau$. The results indicate that magnitudes of $BR({\bar{B}}_0\to a_0(1450)l{\bar{\nu }}_l)$ and $BR(B_s\to K_0^{\ast }(1430)l{\bar{\nu }}_l)$ can arrive at the order of $10^{-4}$, which can be measured in the future experiments to clarify the inner structure of scalar mesons. It is also observed that $BR(B\to K_0^{\ast }(1430){\tau }^{+}{\tau }^{-})$ and $BR(B_s\to f_0(1500){\tau }^{+}{\tau }^{-})$ are an order of magnitude smaller than the corresponding channels of $e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$ final states due to the heavily suppressed phase space . Moreover, the longitudinal lepton polarization asymmetry for $B\to K_0^{\ast }(1430)l\bar{l}$ and $B_s\to f_0(1500)l\bar{l}$ are also investigated, whose values are close to -1 for the $e^{+}{e}^{-}$ and ${\mu }^{+}{\mu }^{-}$ pair except the region close to the end points.

20 pages, 4 figures