Kaon semileptonic decays near the physical point

Extent: 7p.The CKM matrix element jVusj can be extracted from the experimental measurement of semileptonic K -φ decays. The determination depends on theory input for the corresponding vector form factor in QCD. We present a preliminary update on our efforts to compute it in Nf = 2+1 lattice QCD using domain wall fermions for several lattice spacings and with a lightest pion mass of about 170MeV. By using partially twisted boundary conditions we avoid systematic errors associated with an interpolation of the form factor in momentum-transfer, while simulated pion masses near the physical point reduce the systematic error due to the chiral extrapolation.K. Sivalingam, P.A. Boyle, J.M. Flynn, A. Jüttner, C.T. Sachrajda, J.M. Zanotti, RBC and UKQCD Collaborationshttp://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=16