Measurement of CP asymmetries and polarisation fractions in B-s(0) -> K*(0)(K)over-bar*(0) decays

Abstract

An angular analysis of the decay B0 s → K∗0K∗0 is performed using pp collisions corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment at a centre-of-mass energy √ s = 7 TeV. A combined angular and mass analysis separates six helicity amplitudes and allows the measurement of the longitudinal polarisation fraction fL = 0.201 ± 0.057 (stat.) ± 0.040 (syst.) for the B0 s → K∗ (892)0K∗ (892)0 decay. A large scalar contribution from the K∗ 0 (1430) and K∗ 0 (800) resonances is found, allowing the determination of additional CP asymmetries. Triple product and direct CP asymmetries are determined to be compatible with the Standard Model expectations. The branching fraction B(B0 s → K∗ (892)0K∗ (892)0 ) is measured to be (10.8 ± 2.1 (stat.) ± 1.4 (syst.) ± 0.6 (fd/fs)) × 10−6 .