$B_s^0$-${\bar{B}}_s^0$ Oscillations as a New Tool to Explore CP Violation in $D_s^{\pm }$ Decays

Abstract

CP violation in $B_s^0$-${\bar{B}}_s^0$ oscillations is expected at the $10^{-5}$ level in the Standard Model but could be enhanced by New Physics. Using $B_s^0\to D_s^{-}{\ell }^{+}{\nu }_{\ell }$ decays, LHCb has recently reported the new result $(0.39\pm 0.33)\times 10^{-2}$ of the corresponding observable $a_{\mathrm{sl}}^s$. We point out that other current $B$ decay data imply $a_{\mathrm{sl}}^s=(0.004\pm 0.075)\times 10^{-2}$. In view of this strong constraint, we propose to use $B_s^0\to D_s^{-}{\ell }^{+}{\nu }_{\ell }$ and similar flavor-specific decays as a new tool to determine both the production asymmetry between $B_s^0$ and ${\bar{B}}_s^0$ mesons, and the CP asymmetry in the subsequent $D_s^{\pm }$ decays. The former serves as input for analyses of CP violation in $B_s^0$ channels, with significant room for improvement, while the latter offers an exciting laboratory for New Physics.

Comments: 15 pages, 2 figures, improved discussion and presentation, to appear in Physics Letters B