Measurement of the polarisation amplitudes in B0 -> J/psi K*(892)0 decays

TL;DR

This paper measures the polarization amplitudes and phases in B0 -> J/psi K*(892)0 decays using LHCb data, finding precise values and no evidence of direct CP violation, contributing to understanding B meson decay dynamics.

Contribution

It provides the first precise measurement of polarization amplitudes and phases in B0 -> J/psi K*(892)0 decays at 7 TeV, with detailed systematic analysis.

Findings

Measured polarization amplitudes with high precision.

Found no evidence for direct CP violation.

Provided decay phase measurements.

Abstract

An analysis of the decay B0 -> J/psi K*(892)0 is presented using data, corresponding to an integrated luminosity of 1.0fb^-1, collected in pp collisions at a centre-of-mass energy of 7TeV with the LHCb detector. The polarisation amplitudes and the corresponding phases are measured to be |A_{\parallel}|^2 = 0.227 +- 0.004 (stat.) +- 0.011 (syst.), |A_{\perp}|^2 = 0.201 +- 0.004 (stat.) +- 0.008 (syst.), \delta_{\parallel} [rad] = -2.94 +- 0.02 (stat.) +- 0.03 (syst.), \delta_{\perp} [rad] = 2.94 +- 0.02 (stat.) +- 0.02 (syst.). Comparing B0 -> J/psi K*(892)0 and \bar{B}0 -> J/psi \bar{K}*(892)0 decays, no evidence for direct CP violation is found.