Measurements of branching fractions, polarizations, and direct CP-violation asymmetries in B→ρK* and B→f0(980)K* decays

We present measurements of the branching fractions, longitudinal polarization, and direct CP-violation asymmetries for the decays B^+→ρ^0K^(*+) and B^+→f_0(980)K^(*+) with a sample of (467±5)×10^6BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. We observe B+→ρ0K*+ with a significance of 5.3σ and measure the branching fraction B(B^+→ρ^0K^(*+))=(4.6±1.0±0.4)×10^(-6), the longitudinal polarization f_L=0.78±0.12±0.03, and the CP-violation asymmetry A_(CP)=0.31±0.13±0.03. We observe B^+→f_0(980)K^(*+) and measure the branching fraction B(B^+→f_0(980)K^(*+))×B(f_0(980)→π^+π^-)=(4.2±0.6±0.3)×10^(-6) and the CP-violation asymmetry A_(CP)=-0.15±0.12±0.03. The first uncertainty quoted is statistical and the second is systematic.