Hadron Structure from the Feynman-Hellmann Theorem
A. Chambers, J. Dragos, R. Horsley, Y. Nakamura, H. Perlt, D. Pleiter, P. Rakow, G. Schierholz, A. Schiller, K. Somfleth, H. Stüben, R. Young, J. Zanotti
The determination of hadronic form factors at large momentum transfers has been a challenging problem in lattice QCD simulations. Here we show how the Feynman-Hellmann method may be extended to non-forward matrix elements to calculate hadronic form factors in lattice QCD at much higher momenta than previously accessible. We are able to determine the electromagnetic form factors of the pion and nucleon up to approximately 6 GeV$^2$, with results for $G_E/G_M$ in the proton agreeing well with experimental results.