Claude Bernard, Johan Bijinens, Elvira Gamiz, JOhan Relefors
Partially quenched rooted staggered twisted finite volume corrections to K_{l3} decays


The determination of |V_{us}| from kaon semileptonic decays requires the value of the form factor f_{+} (q^{2} = 0) which can be calculated precisely on the lattice. We provide the one loop partially quenched chiral perturbation theory expressions both with and without including the effects of staggered quarks for all form factors at finite volume and with partially twisted boundary conditions for both vector current and scalar density matrix elements at all q^{2}. We point out that at finite volume there are more form factors thanjust f_{+} and f_{-} for the vector current matrix element but that the ward identity is fully satisfied. The size of the finite volume corrections at present lattice sizes is small. We propose the use of partially twisted boundary conditions to determine the size of and test estimates of the finite volume corrections using only a single lattice ensemble.

LU TP 16-50