Kaon semileptonic form factors in QCD with exact chiral symmetry
  We report on our calculation of the kaon semileptonic form factors in Nf=2+1 lattice QCD. Chiral symmetry is exactly preserved by using the overlap quark action for a straightforward comparison with chiral perturbation theory (ChPT). We simulate three pion masses down to 290 MeV at a single lattice spacing of 0.11 fm and at a strange quark mass very close to its physical value. The form factors near zero momentum transfer are precisely calculated by using the all-to-all propagator and twisted boundary conditions. We compare the normalizations and slopes of the form factors with ChPT and experiments. 
JLQCD Collaboration: T. Kaneko, S. Aoki, G. Cossu, X. Feng, H. Fukaya,   S. Hashimoto, J. Noaki, T. Onogi
hep-lat hep-ph