Measurement of the CP violation phase $\phi_s$ in the $B_s$ system at LHCb

TL;DR

This paper reports a preliminary measurement of the CP violation phase phi_s in the Bs meson system using decay modes from LHCb data, providing insights into CP violation and decay dynamics.

Contribution

It presents the first measurements of phi_s in Bs decays to Jpsi K+K- and Jpsi pi+pi-, along with branching fraction and polarization analyses of Bs->JpsiKstbar, enhancing understanding of CP violation and decay contributions.

Findings

Measured phi_s in Bs->JpsiK+K- and Bs->Jpsi pi+pi- decays.

Determined branching fraction and polarization fractions of Bs->JpsiKstbar.

Provided constraints on penguin contributions to Bs->Jpsi phi decay.

Abstract

The interference between Bs decay amplitudes to CP eigenstates Jpsi X directly or including Bs-Bsbar oscillation gives rise to a measurable CP violating phase phi_s. Here, a preliminary measurement of phi_s with Bs -> JpsiK+K- decays, and the measurement using Bs->Jpsipi+pi- decays, both obtained from a sample of 1/fb of pp collisions, collected by the LHCb experiment at a centre-of-mass energy sqrt{s}=7 TeV during 2011, are presented. In addition, the determination of the branching fraction and polarization fractions of Bs->JpsiKstbar, which can be used to constrain the contribution of sub-leading penguin contributions to the decay Bs->Jpsi phi, is shown.