  The decay (B^0)bar -> pi^+ pi^- gamma has a bremsstrahlung component
determined by the amplitude for (B^0)bar -> pi^+ pi^-, as well as a direct
component determined by the penguin interaction V_tb V^*_td c_7 O_7.
Interference of these amplitudes produces a photon energy spectrum d Gamma/d x
= a/x + b + c_1 x + c_2 x^2 + ... (x = 2 E_gamma/m_B) where the terms c_1,2
contain a dependence on the phase alpha_eff = pi - arg[(V_tb V^*_td)^*
Amp((B^0)bar -> pi^+ pi^-)]. We also examine the angular distribution of these
decays, and show that in the presence of strong phases, an untagged
B^0/(B^0)bar beam can exhibit an asymmetry between the pi^+ and pi^- energy
spectra.
