Kaon semileptonic decay from the SU(3)-symmetric point down to physical quark masses

We present an update on the RBC/UKQCD collaboration’s results for the K ! π semileptonic vector form factor at zero momentum transfer from simulations of chiral fermions. Our results cover the whole range of light quark masses between the SU(3)-symmetric and the physical point for three lattice spacings and large physical volumes. Using partially twisted boundary conditions we calculate the form factor directly at zero momentum transfer. The comprehensive set of data points allows for turning the extrapolation in the quar k mass into an interpolation around the physical point thereby removing the dominant systematic uncertainty in previous results, the chiral extrapolation. We briefly discuss our prediction in view of Standard Model phenomenology.