Friday, May 31, 2013

1305.7217 (Peter A. Boyle et al.)

The kaon semileptonic form factor with near physical domain wall quarks    [PDF]

Peter A. Boyle, Jonathan M. Flynn, Nicolas Garron, Andreas Juttner, Chris T. Sachrajda, Karthee Sivalingam, James M. Zanotti
We present a new calculation of the K->pi semileptonic form factor at zero momentum transfer in domain wall lattice QCD with Nf=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=0.09-0.14fm), 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+(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 |Vus|=0.2237(+13/-8) and confirm first-row CKM-unitarity in the Standard Model at the sub per mille level.
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