Measurement of the Lifetime Difference Between B_s Mass Eigenstates

TL;DR

This paper measures the lifetimes and decay rate differences of B_s meson eigenstates, providing the first separate lifetime measurements for heavy and light states using decay amplitude analysis.

Contribution

It introduces the first measurement of the B_s mass eigenstates' lifetimes by analyzing decay amplitudes as a function of decay time.

Findings

Measured tau_L = 1.05 ps and tau_H = 2.07 ps.

Determined DeltaGamma_s/Gamma_s = 65%.

Estimated DeltaGamma_s = 0.47 inverse ps.

Abstract

We present measurements of the lifetimes and polarization amplitudes for B_s --> J/psi phi and B_d --> J/psi K*0 decays. Lifetimes of the heavy (H) and light (L) mass eigenstates in the B_s system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203 +/- 15 B_s decays, we obtain tau_L = (1.05 +{0.16}/-{0.13} +/- 0.02) ps and tau_H = (2.07 +{0.58}/-{0.46} +/- 0.03) ps. Expressed in terms of the difference DeltaGamma_s and average Gamma_s, of the decay rates of the two eigenstates, the results are DeltaGamma_s/Gamma_s = (65 +{25}/-{33} +/- 1)%, and DeltaGamma_s = (0.47 +{0.19}/-{0.24} +/- 0.01) inverse ps.