# Kl3 and pion form factors using partially twisted boundary conditions

Flynn, J.M., de Lima, H. Pedroso , Sachrajda, C.T., Boyle, P.A., Kelly, C., Maynard, C.M., Zanotti, J.M. and Jüttner, A. (2008) Kl3 and pion form factors using partially twisted boundary conditions. Proceedings of Science, LATTICE2008, 287.

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## Description/Abstract

We compute the Kl3 and pion form factors using partially twisted boundary
conditions. The twists are chosen so that the Kl3 form factors are calculated
directly at zero momentum transfer (q^2=0), removing the need for a q^2
interpolation, while the pion form factor is determined at values of q^2 close
to q^2=0. The simulations are performed on an ensemble of the RBC/UKQCD
collaboration's gauge configurations with Domain Wall Fermions and the Iwaski
gauge action with an inverse lattice spacing of 1.73(3) GeV. Simulating at a
single pion mass of 330 MeV, we find the pion charge radius to be < r^2>_{330
MeV}=0.354(31) fm^2 which, using NLO SU(2) chiral perturbation theory,
translates to a value of <r_\pi^2>=0.418(31) fm^2 for a physical pion. For the
value of the Kl3 form factor, f_{K\pi}^+(q^2), determined directly at q^2=0, we
find a value of f_{K\pi}^+(0)=0.9742(41) at this particular quark mass, which
agrees well with our earlier result (0.9774(35)) obtained using the standard,
indirect method.

Item Type: Article Imported from arXiv 1824-8039 (electronic) Q Science > QC Physics University Structure - Pre August 2011 > School of Physics and Astronomy > Southampton High Energy Physics 144005 14 Apr 2010 12:31 27 Mar 2014 19:05 http://eprints.soton.ac.uk/id/eprint/144005