Technicolor corrections on $B_{s,d} \to γγ$ 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 $\calb(B_{s,d} \to γγ)$ and CP violating asymmetries $\rcpm(B_{s,d} \to γγ)$ in the QCD factorization based on the heavy-quark limit $m_b \gg Λ_{QCD}$. Using the considered parameter space, we find that (a) for both $B_s\to γγ$ and $B_d \to γγ$ decays, the new physics contribution can provide a factor of two to six enhancement to their branching ratios, (b) for the $B_s \to γγ$ decay, its direct CP violation is very small in both the SM and TC2 model, and (c) the CP violating asymmetry $\rcpm(B_d \to γγ)$ 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.

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