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The Double Radiative Decays $B\toγγ$ in the Heavy Quark Limit

Stefan W. Bosch·Gerhard Buchalla
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Abstract

We analyze the double radiative B-meson decays B_s -> gamma gamma and B_d -> gamma gamma in QCD factorization based on the heavy-quark limit m_b >> Lambda_QCD. We systematically discuss the various contributions to these exclusive processes. The dominant effect arises from the magnetic-moment type transition b -> s(d) gamma where an additional photon is emitted from the light quark (one-particle reducible diagram). The contributions from one-particle irreducible diagrams are power suppressed. We argue that they are still calculable within QCD factorization. They are used to compute the CP-asymmetries in B -> gamma gamma and to estimate so-called long-distance contributions in B and D -> gamma gamma. Numerical results are presented for branching ratios and CP asymmetries.

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Stefan W. Bosch, Gerhard Buchalla. 2002-08-22. The Double Radiative Decays $B\toγγ$ in the Heavy Quark Limit. https://doi.org/10.1088/1126-6708%2F2002%2F08%2F054

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