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 $ΔΓ_s / Gamma_s$ from $B_s \to D_s^{(*)+} D_s^{(*)-}$ decay branching fraction measurements at $e^+ e^-$ colliders running on the $Υ$(5S) resonance is discussed. The expected accuracies of the $B_s \to D_s^{(*)+} D_s^{(*)-}$ branching fraction measurements and the $ΔΓ_s / Γ_s$ determination with 50fb$^{-1}$ of data at the $Υ$(5S) are estimated using Monte Carlo simulation. Comparison of that measurement with a directly measured $ΔΓ_s / Γ_s$ value within and beyond Standard Model is discussed. A new method of estimating $ΔΓ_s / Γ_s$ is proposed, based on comparing the CP-even and CP-odd components in $B^0 \to J/ΨK^{*0}$ and $B_s \to J/Ψϕ$ decays. A comparison of $B_s$ and $B^0$ lifetime measurements with theoretical predictions is discussed.