Measuring B -> rho pi decays and the unitarity angle alpha

The decay mode B -> rho pi is currently studied as a channel allowing, in principle, to measure without ambiguities the angle alpha of the unitarity triangle. It is also investigated by the CLEO Collaboration where a branching ratio larger than expected for the decay mode B+/- -> rho0 pi+/- has been found. We investigate the role that the B* and B(0+) resonances play in these analyses.