Paper detail

Study of $\bar{B}_s^0 \to (D_s^+,D_s^{*+}) l^-\barν_l$ decays in the pQCD factorization approach

The $\bar{B}_s^0 \to D_s^{(*)+} l^- \barν_l$ semileptonic decays were calculated in the framework of the standard model (SM) by employing the perturbative QCD (pQCD) factorization approach. We defined four ratios of the branching ratios of the considered decays $R(D_s^{(*)})$ and $R_{D_s}^{l,τ}$. From the numerical results and phenomenological analysis we found that: (a) The pQCD predictions for the branching ratios $Br(\bar{B}_s^0 \to D_s^{(*)+} l^-\barν_l)$ generally agree well with the previous theoretical predictions; (b) For the four ratios, the pQCD predictions are $R(D_s)= 0.392 \pm 0.022$, $R(D_s^{*})= 0.302\pm 0.011$, $R_{D_{s}}^l=0.448^{+0.058}_{-0.041}$ and $R_{D_{s}}^τ=0.582^{+0.071}_{-0.045}$, which show a very good $SU(3)_F$ flavor symmetry with the corresponding ratios for $B\to D^{(*)} l^- \barν_l$ decays; and (c) we strongly suggest the measurements of the new ratios $R(D_s^{(*)})$ and $R_{D_{s}}^{l,τ}$ in the forthcoming Super-B experiments.