K(l3) form factor with N(f) = 2+1 dynamical domain wall fermions

We present the latest results from the UKQCD/RBC collaborations for the Kl3 form factor from simulations with 2 + 1 flavours of dynamical domain wall quarks. Simulations are performed on lattices with two different volumes and four values of the light quark mass, allowing for an extrapolation to the chiral limit. The analysis includes a thorough investigation into the sources of systematic error in our fits. After interpolating to zero momentum transfer, we obtain f+(0) = 0.964(5) (or δf = -0.013(5)) which, when combined with the latest experimental results for Kl3 decays, leads to |Vus| = 0.2249(14).