Radiative corrections to decay amplitudes in lattice QCD

Understand

The precision of lattice QCD computations of many quantities has reached such a precision that isospin-breaking corrections, including electromagnetism, must be included if further progress is to be made in extracting fundamental information, such as the values of Cabibbo-Kobayashi-Maskawa matrix elements, from experimental measurements.

• We discuss the framework for including radiative corrections in leptonic and semileptonic decays of hadrons, including the treatment of infrared divergences.
• We briefly review isospin breaking in leptonic decays and present the first numerical results for the ratio $\Gamma(K_{\mu2})/\Gamma(\pi_{\mu2})$ in which these corrections have been included.
• We also discuss the additional theoretical issues which arise when including electromagnetic corrections to semileptonic decays, such as $K_{\ell3}$ decays.