Feynman--Hellmann approach to transition matrix elements and quasi-degenerate energy states

Author:

M. Batelaan, K. U. Can, R. Horsley, Y. Nakamura, P. E. L. Rakow, G. Schierholz, H. Stüben, R. D. Young, J. M. Zanotti

Keyword:

High Energy Physics - Lattice, High Energy Physics - Lattice (hep-lat)

journal:

Phys. Rev D 108, 034507 (2023)

date:

2023-05-08 16:00:00

Abstract

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 diagonalise 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.

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