Measurement of the Lifetime Difference in the B_s^0 System

TL;DR

This paper measures the lifetime difference and decay properties of the B_s^0 meson, providing key parameters for understanding CP violation and meson mixing in particle physics.

Contribution

It presents the first precise measurements of the B_s^0 lifetime, CP-odd fraction, and width difference, with improved accuracy over previous results.

Findings

CP-odd fraction at time zero: 0.16 +/- 0.10 (stat) +/- 0.02 (syst)

Average B_s^0 lifetime: 1.39^{+0.13}_{-0.16} (stat) ^{+0.01}_{-0.02} (syst) ps

Width difference ratio: 0.24^{+0.28}_{-0.38} (stat) ^{+0.03}_{-0.04} (syst)

Abstract

We present a study of the decay B_s^0 -> J/psi phi We obtain the CP-odd fraction in the final state at time zero, R_perp = 0.16 +/- 0.10 (stat) +/- 0.02 (syst), the average lifetime of the (B_s, B_sbar) system, tau (B_s^0) =1.39^{+0.13}_{-0.16} (stat) ^{+0.01}_{-0.02} (syst) ps, and the relative width difference between the heavy and light mass eigenstates, Delta Gamma/Gamma = (Gamma_L - Gamma_H)/Gamma =0.24^{+0.28}_{-0.38} (stat) ^{+0.03}_{-0.04} (syst). With the additional constraint from the world average of the B_s^0$lifetime measurements using semileptonic decays, we find tau (B_s^0)= 1.39 +/- 0.06 ~ps and Delta Gamma/\Gamma = 0.25^{+0.14}_{-0.15}. For the ratio of the B_s^0 and B^0 lifetimes we obtain tau(B_s^0)/tau(B^0)} = 0.91 +/- 0.09 (stat) +/- 0.003 (syst).