Technicolor corrections on $B_{s,d}\to \gamma \gamma$ decays in QCD factorization

Abstract

Within the framework of the Top-color-assisted Technicolor (TC2) model, we calculate the new physics contributions to the branching ratios $\text{calb}(B_{s,d}\to \gamma \gamma )$ and CP violating asymmetries $\text{rcpm}(B_{s,d}\to \gamma \gamma )$ in the QCD factorization based on the heavy-quark limit $m_b\gg {\Lambda }_{QCD}$. Using the considered parameter space, we find that (a) for both $B_s\to \gamma \gamma$ and $B_d\to \gamma \gamma$ decays, the new physics contribution can provide a factor of two to six enhancement to their branching ratios, (b) for the $B_s\to \gamma \gamma$ decay, its direct CP violation is very small in both the SM and TC2 model, and (c) the CP violating asymmetry $\text{rcpm}(B_d\to \gamma \gamma )$ is around the ten percent level in both the SM and TC2 model, but the sign of CP asymmetry in the TC2 model is different from that in the SM.

Comments: 23 pages, Revtex, 9 PS/EPs figures, minor corrections, final version to appear in Phys.Rev. D