Measurement of Branching Fractions and Polarization in B -> phi K^{(*)} Decays

TL;DR

This paper reports the first measurement of decay amplitudes and branching fractions in B -> phi K^{(*)} decays, analyzing angular distributions to understand polarization states and CP asymmetries using data from the Belle detector.

Contribution

It provides the first measurement of decay amplitudes and polarization in B -> phi K^{*} decays, offering new insights into decay dynamics and CP violation.

Findings

Measured decay amplitudes for phi K^{*0} helicity states.

Branching fractions for B -> phi K^{(*)} decays.

CP asymmetries are consistent with zero.

Abstract

We present the first measurement of decay amplitudes in B -> phi K^* and measurements of branching fractions in B -> phi K^{(*)} decays based on 78.1 fb^{-1} of data recorded at the Upsilon(4S) resonance with the Belle detector at the KEKB e^+ e^- storage ring. The decay amplitudes for the different phi K^{*0} helicity states are measured from the angular distributions of final state particles in the transversity basis. The longitudinal and transverse complex amplitudes are |A_0|^2 = 0.43 +- 0.09 +- 0.04, |A_perp|^2 = 0.41 +- 0.10 +- 0.04, arg(A_parallel) = -2.57 +- 0.39 +- 0.09, and arg(A_perp) = 0.48 +- 0.32 +- 0.06. The direct CP-violating asymmetries are found to be consistent with zero.