Speaker
Description
The decreasing uncertainties in theoretical predictions and experimental measurements of several hadronic observables related to weak processes, which in many cases are now smaller than O(1%), require theoretical calculations to include subleading corrections that were neglected so far. Precise determinations of leptonic and semi-leptonic decay rates, including $\text{QED}$ and strong isospin-breaking effects, can play a central role in solving the current tensions in the first-row unitarity of the $\text{CKM}$ matrix. In this talk we discuss the recent progress on lattice calculations of isospin-breaking corrections to leptonic decay rates of pseudoscalar mesons, presenting new results by the $\text{RBC/UKQCD}$ collaboration. The inclusion of long-distance $\text{QED}$ interactions on the lattice, evaluated using the $\text{QED}_\text{L}$ prescription, produces sizeable finite-volume corrections. The relevant role of these effects in the high-precision determination of leptonic decay rates will be discussed, along with prospects for future improvement.
