## Abstract

We present a new calculation of the K -> pi semileptonic form factor at zero momentum transfer in domain wall lattice QCD with N-f = 2+1 dynamical quark flavours. By using partially twisted boundary conditions we simulate directly at the phenomenologically relevant point of zero momentum transfer. We perform a joint analysis for all available ensembles which include three different lattice spacings (a = 0.09 - 0.14 fm), large physical volumes (m(pi)L > 3.9) and pion masses as low as 171 MeV. The comprehensive set of simulation points allows for a detailed study of systematic effects leading to the prediction f(+)(K pi)(0) = 0.9670(20)((+18)(-46)), where the first error is statistical and the second error systematic. The result allows us to extract the CKM-matrix element vertical bar V-us vertical bar = 0.2237((+13)(-8)) and confirm first-row CKM-unitarity in the Standard Model at the sub per mille level.

Original language | English |
---|---|

Article number | 132 |

Number of pages | 16 |

Journal | Journal of High Energy Physics |

Issue number | 8 |

DOIs | |

Publication status | Published - Aug 2013 |

## Keywords

- Lattice QCD
- Quark Masses and SM Parameters
- Kaon Physics
- Standard Model
- TWISTED BOUNDARY-CONDITIONS
- CHIRAL FERMIONS
- LATTICE
- MODEL
- DECAYS