Measurement of the B-->J/psi K^*(892) decay amplitudes

TL;DR

This paper measures decay amplitudes in B-->J/psi K^*(892) decays, revealing polarization fractions and phase differences that challenge the factorization hypothesis, using data from the BABAR detector.

Contribution

First measurement of decay amplitudes and polarization fractions in B-->J/psi K^*(892) decays with evidence for non-factorizable effects.

Findings

P-wave fraction R_perp = (16.0±3.2±1.4)%

Longitudinal polarization fraction = (59.7±2.8±2.4)%

Relative phase φ_ll ≈ 2.50 radians

Abstract

We present a measurement of the decay amplitudes in B-->J/psi K^*(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_perp = (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_ll = 2.50+/-0.20+/-0.08 radians, favors a departure from the factorization hypothesis. Although the decay B-->J/psi Kpi proceeds mainly via K^*(892), there is also evidence for K^*_2(1430) and Kpi S-wave contributions.