Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">B</mml:mi><mml:mo>→</mml:mo><mml:mspace/><mml:mi mathvariant="italic">J</mml:mi><mml:mi>/</mml:mi><mml:mi mathvariant="italic">ψ</mml:mi><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">K</mml:mi></mml:mrow><mml:mrow><mml:mi>*</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>(892) Decay Amplitudes

We present a measurement of the decay amplitudes in B-->J/psiK*(892) channels using 20.7 fb(-1) of data collected at the Upsilon(4S) resonance with the BABAR detector at PEP-II. We measure a P-wave fraction R(perpendicular) = (16.0 +/- 3.2 +/- 1.4)% and a longitudinal polarization fraction (59.7 +/- 2.8 +/- 2.4)%. The measurement of a relative phase that is neither 0 nor pi, phi = 2.50 +/- 0.20 +/-0.08 radians, favors a departure from the factorization hypothesis. Although the decay B-->/psiK(pi) proceeds mainly via K*(892), there is also evidence for K2*(1430) and K(pi) S-wave contributions.