Measurement of lifetime and decay-width difference in Bs0→J/ψ decays

Abstract

We measure the mean lifetime τ=2/(ΓL+ΓH) and the decay-width difference ΔΓ=ΓL-ΓH of the light and heavy mass eigenstates of the Bs0 meson, BsL0 and BsH0, in Bs0→J/ψ decays using 1.7fb-1 of data collected with the CDF II detector at the Fermilab Tevatron pp̄ collider. Assuming CP conservation, a good approximation for the Bs0 system in the standard model, we obtain ΔΓ=0.076-0.063+0. 059(stat)±0.006(syst)ps-1 and τ=1.52±0.04(stat)±0. 02(syst)ps, the most precise measurements to date. Our constraints on the weak phase and ΔΓ are consistent with CP conservation. © 2008 The American Physical Society.