Determination of $\Delta {\Gamma }_s$ from Analysis of Untagged Decays $B_s^0\to J/\psi \varphi$ by Using the Method of Angular Moments

Abstract

The performance of the method of angular moments on the $\Delta {\Gamma }_s$ determination from analysis of untagged decays $B_s^0(t),{\bar{B}}_s^0(t)\to J/\psi (\to l^{+}{l}^{-})\varphi (\to K^{+}{K}^{-})$ is examined. The results of Monte Carlo studies with evaluation of measurement errors are presented. The method of angular moments gives stable results for the estimate of $\Delta {\Gamma }_s$ and is found to be an efficient and flexible tool for the quantitative investigation of the $B_s^0\to J/\psi \varphi$ decay. The statistical error of the ratio $\Delta {\Gamma }_s/{\Gamma }_s$ for values of this ratio in the interval [0.03, 0.3] was found to be independent on this value, being 0.015 for $10^5$ events.

Comments: 19 pages, 3 figures, submitted to "Particle and Nuclei, Letters"