Measurement of the CP-Violating Phase beta_s in B0s -> J/Psi Phi Decays with the CDF II Detector

Abstract

We present a measurement of the \CP-violating parameter \betas using approximately 6500 $\text{BsJpsiPhi}$ decays reconstructed with the CDF\,II detector in a sample of $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV corresponding to 5.2 fb${}^{-1}$ integrated luminosity produced by the Tevatron Collider at Fermilab. We find the \CP-violating phase to be within the range $\text{betas}\in [0.02,0.52]\cup [1.08,1.55]$ at 68% confidence level where the coverage property of the quoted interval is guaranteed using a frequentist statistical analysis. This result is in agreement with the standard model expectation at the level of about one Gaussian standard deviation. We consider the inclusion of a potential $S$-wave contribution to the $\text{Bs}\to J/\psi K^{+}{K}^{-}$ final state which is found to be negligible over the mass interval $1.009<m(K^{+}{K}^{-})<1.028\text{gevcc}$. Assuming the standard model prediction for the \CP-violating phase \betas, we find the \Bs decay width difference to be $\text{deltaG}=0.075\pm 0.035\text{(stat)}\pm 0.006\text{(syst)}\text{ps}$. We also present the most precise measurements of the \Bs mean lifetime $\tau (\text{Bs})=1.529\pm 0.025\text{(stat)}\pm 0.012\text{(syst)}$ ps, the polarization fractions $|A_0(0){|}^2=0.524\pm 0.013\text{(stat)}\pm 0.015\text{(syst)}$ and $|A_{\parallel }(0){|}^2=0.231\pm 0.014\text{(stat)}\pm 0.015\text{(syst)}$, as well as the strong phase ${\delta }_{\perp }=2.95\pm 0.64\text{(stat)}\pm 0.07\text{(syst)}\text{rad}$. In addition, we report an alternative Bayesian analysis that gives results consistent with the frequentist approach.

Comments: 32 pages, 24 figures, 5 tables; submitted to Phys. Rev. D