Measurement of the CP-violating phase $\phi_s$ in $\bar{B}^{0}_{s}\to D_{s}^{+}D_{s}^{-}$ decays

TL;DR

This paper reports a measurement of the CP-violating phase $\,phi_s$ in $\,ar{B}_s^0 o D_s^+ D_s^-$ decays using LHCb data, finding results consistent with the Standard Model.

Contribution

First measurement of $\,phi_s$ in $\,ar{B}_s^0 o D_s^+ D_s^-$ decays without constraining $|\, extlambda|=1$, providing a more general analysis of CP violation.

Findings

Measured $\,phi_s = 0.02 \, extpm \,0.17 \,\text{(stat)} \,\pm \,0.02 \,\text{(syst)}$ radians.

Determined $|\lambda| = 0.91^{+0.18}_{-0.15}$ (stat) $\pm 0.02$ (syst).

Results are consistent with Standard Model predictions.

Abstract

We present a measurement of the $CP$-violating weak mixing phase $\phi_s$ using the decay $\bar{B}^{0}_{s}\to D_{s}^{+}D_{s}^{-}$ in a data sample corresponding to $3.0$ fb$^{-1}$ of integrated luminosity collected with the LHCb detector in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not constrain $|\lambda|=1$ to allow for the presence of $CP$ violation in decay, yields $\phi_s = 0.02 \pm 0.17$ (stat) $\pm 0.02$ (syst) rad, $|\lambda| = 0.91^{+0.18}_{-0.15}$ (stat) $\pm0.02$ (syst). This result is consistent with the Standard Model expectation.