The pi+ pi+ scattering length from maximally twisted mass lattice QCD
Abstract
We calculate the s-wave pion-pion scattering length in the isospin I=2 channel in lattice QCD for pion masses ranging from 270 Mev to 485 Mev using two flavors of maximally twisted mass fermions at a lattice spacing of 0.086 fm. Additionally, we check for lattice artifacts with one calculation at a finer lattice spacing of 0.067 fm. We use chiral perturbation theory at next-to-leading order to extrapolate our results. At the physical pion mass, we find mpi apipi(I=2)=-0.04385(28)(38) for the scattering length, where the first error is statistical and the second is our estimate of several systematic effects.
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