Measurement of the B-s(0) -> J/psi K-S(0) branching fraction

The B-s(0) -> J/psi K-s(0) branching fraction is measured in a data sample corresponding to 0.41 fb(-1) of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to the penguin contributions affecting the sin 2 beta measurement from B-0 -> J/psi K-s(0)). The time-integrated branching fraction is measured to be B(B-s(0) -> J/psi K-s(0)) = (1.83 +/- 0.28) x 10(-5). This is the most precise measurement to date. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved.