Electroweak effects in the extraction of the CKM angle $\gamma$ from $B\to D\pi$ decays

Abstract

The angle $\gamma$ of the standard CKM unitarity triangle can be determined from tree-level $B$-meson decays essentially without hadronic uncertainties. We calculate the second-order electroweak corrections for the $B\to D\pi$ modes and show that their impact on the determination of $\gamma$ could be enhanced by an accidental cancellation of poorly known hadronic matrix elements. However, we do not expect the resulting shift in $\gamma$ to exceed $|\delta {\gamma }^{D\pi }/\gamma |\lesssim \mathcal{O}\left(10^{-4}\right)$.

Comments: 13 pages, 4 figures. Version as published in Phys.Lett.B