Determining Delta_Gamma_s / Gamma_s from Bf(B_s \to D_s^{(*)+} D_s{(*)-}) measurements at e^+ e^- colliders running on the Y(5S) resonance

Abstract

The feasibility of determining $\Delta {\Gamma }_s/Gamm{a}_s$ from $B_s\to D_s^{(\ast )+}{D}_s^{(\ast )-}$ decay branching fraction measurements at $e^{+}{e}^{-}$ colliders running on the ${\rm Y}$(5S) resonance is discussed. The expected accuracies of the $B_s\to D_s^{(\ast )+}{D}_s^{(\ast )-}$ branching fraction measurements and the $\Delta {\Gamma }_s/{\Gamma }_s$ determination with 50fb${}^{-1}$ of data at the ${\rm Y}$(5S) are estimated using Monte Carlo simulation. Comparison of that measurement with a directly measured $\Delta {\Gamma }_s/{\Gamma }_s$ value within and beyond Standard Model is discussed. A new method of estimating $\Delta {\Gamma }_s/{\Gamma }_s$ is proposed, based on comparing the CP-even and CP-odd components in $B^0\to J/\Psi K^{\ast 0}$ and $B_s\to J/\Psi \varphi$ decays. A comparison of $B_s$ and $B^0$ lifetime measurements with theoretical predictions is discussed.

Comments: 8 pages