K > pi vector form factor with N_f=2+1+1 Twisted Mass fermions
Abstract
We present a lattice QCD determination of the vector form factor of the kaon semileptonic decay K > pi l nu which is relevant for the extraction of the CKM matrix element V_{us} from experimental data. Our result is based on the gauge configurations produced by the European Twisted Mass Collaboration with N_f=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 preliminary estimate for the vector form factor at zero momentum transfer is f_+(0)=0.9683(65), where the uncertainty is both statistical and systematic. By combining our result with the experimental value of f_+(0)V_{us} we obtain V_{us}=0.2234(16), which satisfies the unitarity constraint of the Standard Model at the permille level.
 Publication:

arXiv eprints
 Pub Date:
 November 2014
 arXiv:
 arXiv:1411.1201
 Bibcode:
 2014arXiv1411.1201C
 Keywords:

 High Energy Physics  Lattice