Nucleon structure with partially twisted boundary conditions

Abstract

A large number of fundamental hadron structure observables are de_s13_s1764257_s19ned in the limit of vanish- ing momentum transfer, but at the same time cannot be directly extracted from forward matrix elements. This is a challenge for current lattice QCD simulations, where volumes and lattice spacings are such that the lowest accessible non-zero momentum transfers are _s13_s178764_s19 0.15 GeV^2 and larger, making in general model-dependent extrapolations to the forward limit necessary. Twisted boundary conditions for the valence quarks provide the opportunity to study hadronic matrix el- ements in dynamical lattice QCD calculations for almost arbitrary hadron momenta. We present preliminary results for the Dirac- and Pauli form factors and the form factors of the energy mo- mentum tensor for the nucleon very close to the forward limit, using partially twisted boundary conditions. The calculations are based on gauge con_s13_s1764257_s19gurations generated with two _s13_s1764258_s19avors of clover-improved Wilson fermions.