$D_{(s)}(2S)$ and $D^{*}_{(s)}(2S)$ production in nonleptonic $B_{(s)}$ weak decays

Abstract

Recently, many new excited states of heavy mesons have been discovered in recent experiments, including radially excited states. The production processes of these states from the $B_{(s)}$ meson have drawn significant interest. In this paper, we use the covariant light-front approach to study the nonleptonic $B_{(s)}$ meson decays to the first radially excited states $D_{(s)}(2S)$ and $D^{*}_{(s)}(2S)$. Our results reveal that many channels exhibit large branching ratios in the range $10^{-5}\sim 10^{-4}$, even up to $10^{-3}$ for individual channels, which are detectable by current experiments. Our predictions for the decays $B_{(s)}\to D^{(*)}_{(s)}(2S)(\pi,\rho,K^{(*)})$ are larger than those given by the Bethe-Salpeter (BS) equation method, but agree well with the relativistic quark mode (RQM) and the relativistic independent quark model (RIQM) calculations. For comparison, we also present the branching ratios of the decays $B_{(s)}\to D^{(*)}_{(s)}(1S)(\pi,\rho,K^{(*)})$, which are comparable with other theoretical results and the data. Although the branching ratios of the decays $B_{(s)} \to D^{*}_{(s)}(1S)(\rho,K^*)$ are much larger than those of the decays $B_{(s)} \to D^{*}_{(s)}(2S)(\rho,K^*)$, the polarization properties between them are similar, that is, the longitudinal polarization fractions are dominant and can amount roughly to $90\%$.