Measurements of the Branching Fractions and Helicity Amplitudes in B --> D* rho Decays

TL;DR

This paper reports measurements of branching fractions and helicity amplitudes in B meson decays to D* rho, testing factorization and revealing complex final-state interactions.

Contribution

It provides new experimental data on B -> D* rho decays, including polarization fractions and phase information, supporting the factorization hypothesis.

Findings

Longitudinal polarization fractions are consistent with factorization.

Evidence of non-trivial phases in helicity amplitudes.

Measurements align with theoretical expectations for similar decays.

Abstract

Using 9.1 fb-1 of e+ e- data collected at the Upsilon(4S) with the CLEO detector using the Cornell Electron Storage Ring, measurements are reported for both the branching fractions and the helicity amplitudes for the decays B- -> D*0 rho- and B0bar -> D*+ rho-. The fraction of longitudinal polarization in B0bar -> D*+ rho- is found to be consistent with that in B0bar -> D*+ l- nubar at q^2 = M^2_rho, indicating that the factorization approximation works well. The longitudinal polarization in the B- mode is similar. The measurements also show evidence of non-trivial final-state interaction phases for the helicity amplitudes.