Chiral behavior of kaon semileptonic form factors in lattice QCD with   exact chiral symmetry
  We calculate the kaon semileptonic form factors in lattice QCD with three flavors of dynamical overlap quarks. Gauge ensembles are generated at pion masses as low as 290 MeV and at a strange quark mass near its physical value. We precisely calculate relevant meson correlators using the all-to-all quark propagator. Twisted boundary conditions and the reweighting technique are employed to vary the momentum transfer and the strange quark mass. We discuss the chiral behavior of the form factors by comparing with chiral perturbation theory and experiments. 
JLQCD Collaboration: T. Kaneko, S. Aoki, G. Cossu, X. Feng, H. Fukaya,   S. Hashimoto, J. Noaki, T. Onogi
hep-lat hep-ph