出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：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
(q2 = 0), removing the need for a q2 interpolation, while the pion form factor is determined at
values of q2 close to q2 = 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 330MeV, we
find the pion charge radius to be hr2i330MeV = 0.354(31) fm2 which, using NLO SU(2) chiral
perturbation theory, translates to a value of hr2pi = 0.418(31) fm2 for a physical pion. For the
value of the Kℓ3 form factor, f +
Kp (q2), determined directly at q2 = 0, we find a value of f +
Kp (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.
