2015/03/05 by C. Sachrajda, Sachrajda, C.
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #hep-lat
paper · pdf · doi:10.48550/arxiv.1503.01691
Plenary talk presented at the 32nd International Symposium on Lattice Field Theory (Lattice 2014), Columbia University, June 23 - 28 2014
arxiv created 2015/03/05 · arxiv updated 2015/03/06
Standard lattice calculations in flavour physics or in studies of hadronic structure are based on the evaluation of matrix elements of local composite operators between hadronic states or the vacuum. In this talk I discuss developments aimed at the computation of long-distance, and hence non-local, contributions to such processes. In particular, I consider the calculation of the KL-KS mass difference ΔmK=mKL-mKS and the amplitude for the rare-kaon decay processes K→πℓ+ℓ-, where the lepton ℓ=e or μ. Lattice calculations of the long-distance contributions to the indirect CP-violating parameter εK and to the rare decays K→πνν are also beginning. Finally I discuss the possibility of including O(α) electromagnetic effects in computations of leptonic and semileptonic decay widths, where the novel feature is the presence of infrared divergences. This implies that contributions to the width from processes with a real photon in the final state must be combined with those with a virtual photon in the amplitude so that the infrared divergences cancel by the Bloch-Nordsieck mechanism. I present a proposed procedure for lattice computations of the O(α) contributions with control of the cancellation of the infrared divergences.