Seminarium "Teoria cząstek elementarnych i kosmologia"

In my talk, I will report on the computation of QED radiative corrections to the rare leptonic decay of strange B mesons. In the previous literature, only the QED corrections above the m_b scale have been evaluated. I will outline an approach to compute corrections below the m_b scale using soft-collinear effective theory. It reveals an unexpected enhancement due to a "non-local annihilation" effect. Moreover, exchange of a soft fermion generates additional logarithmic enhancement. Therefore, the effect is interesting not only for the phenomenological reasons but also illustrates the intricate structure of QED in bound states. The talk will be based on Phys.Rev.Lett. 120, 011801 (arXiv:1708.09152).