### Abstract

We discuss the reduction of errors in the calculation of the form factor f _{+} ^{Kπ} (0) with HISQ fermions on the N_{f} = 2+1+1 MILC configurations from increased statistics on some key ensembles, new data on ensembles with lattice spacings down to 0:042 fm and the study of finite-volume effects within staggered ChPT. We also study the implications for the unitarity of the CKM matrix in the first row and for current tensions with leptonic determinations of |V_{us}|.

Original language | English (US) |
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Journal | Proceedings of Science |

Volume | Part F128557 |

State | Published - 2016 |

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### ASJC Scopus subject areas

- General

### Cite this

_{f}= 2+1+1 HISQ fermions and physical light-quark masses.

*Proceedings of Science*,

*Part F128557*.