2015/11/16 by N. Carrasco, P. Lami, Carrasco, N. +7
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Lattice (hep-lat) #High Energy Physics - Phenomenology (hep-ph) #hep-lat #hep-ph
paper · pdf · doi:10.48550/arxiv.1511.04880
7 pages, 2 figures, to appear in Proc. of the XXXIII Int'l Symposium on Lattice Field Theory, 14-18 July 20-15, Kobe (Japan)
arxiv created 2015/11/16 · arxiv updated 2015/11/19
We present a lattice QCD determination of the vector and scalar form factors of the kaon semileptonic decay K → πℓ ν, which is relevant for the determination of the CKM matrix element |Vus| from experimental data. Our results are based on the gauge configurations produced by the European Twisted Mass Collaboration with Nf = 2+1+1 dynamical fermions. We simulated at three different values of the lattice spacing and with pion masses as small as 210 MeV. Our estimate for the vector form factor at zero 4-momentum transfer is f+(0) = 0.9709 (46), where the uncertainty is both statistical and systematic. By combining our result with the latest experimental value of f+(0)|Vus| we obtain |Vus| = 0.2230 (11), which satisfies the unitarity constraint of the Standard Model at the permille level using the updated determination of |Vud| coming from superallowed nuclear β decays. We present also the momentum dependence of the vector and scalar form factors in the whole range of values of the squared 4-momentum transfer measured in Kℓ 3 decays, obtaining a good agreement with the experimental data.