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CP-Violation in the decay B^0, (B^0)bar -> pi^+ pi^- gamma

L. M. Sehgal·J. van Leusen
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Abstract

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.

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L. M. Sehgal, J. van Leusen. 2002-08-30. CP-Violation in the decay B^0, (B^0)bar -> pi^+ pi^- gamma. https://doi.org/10.1016/s0370-2693(02)02708-9

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