Measurement of CP asymmetries and polarisation fractions in B[superscript 0][subscript s]→K[superscript ∗0][¯ over K][superscript ∗0] decays

Abstract

An angular analysis of the decay B[subscript s][superscript 0] →K[superscript ∗0][¯ over K][superscript ∗0] is performed using pp collisions corresponding to an integrated luminosity of 1.0 fb[superscript −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 f[subscript L] = 0.201 ± 0.057 (stat.) ± 0.040 (syst.) for the (Formula Presented) decay. A large scalar contribution from the K[subscript 0][superscript ∗] (1430) and K[subscript 0][superscript ∗] (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(B[subscript s]→ K[superscript ∗] (892)[superscript 0] [¯ over K][superscript *] (892)[superscript 0] is measured to be (10.8 ± 2.1 (stat.) ± 1.4 (syst.) ± 0.6 (f[subscript d]/f[subscript s])) × 10[superscript −6]. Keywords: CP violation, Hadron-Hadron Scattering, Polarization, B physics, Flavour Changing Neutral Currents