Feynman-Hellmann approach to transition matrix elements

The Feynman-Hellmann approach to computing matrix elements in lattice QCD by first adding a perturbing operator to the action is described using the transition matrix and the Dyson expansion formalism. This perturbs the energies in the two-point baryon correlation function, from which the matrix element can be obtained. In particular at leading order in the perturbation we need to diagonalize a matrix of near-degenerate energies. While the method is general for all hadrons, we apply it here to a study of a sigma to nucleon baryon transition vector matrix element.

Automated summary

The Feynman-Hellmann approach is a method for computing matrix elements in lattice quantum chromodynamics (QCD) by perturbing the energies and obtaining the matrix elements. It can be applied to various hadrons, and we apply it here to study the matrix element of the sigma to nucleon baryon transition.