Hadron matrix elements, lattice QCD and the Feynman-Hellmann approach
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A major objective of lattice QCD is the computation of hadronic
matrix elements. The standard method is to use three-point and
four-point correlation functions. An alternative approach,
requiring only the computation of two-point correlation functions
is to use the Feynman-Hellmann theorem. In this talk we develop this
method up to second order in perturbation theory, in a context appropriate
for lattice QCD. This encompasses the Compton Amplitude (which forms the
basis for deep inelastic scattering) and hadron scattering.
Some numerical results are presented showing results indicating what
this approach might achieve.