# On the Feynman-Hellmann theorem in quantum field theory and the calculation of matrix elements

@article{Bouchard2016OnTF, title={On the Feynman-Hellmann theorem in quantum field theory and the calculation of matrix elements}, author={C. Bouchard and Chia-Cheng Chang and Thorsten Kurth and Kostas Orginos and Andr{\'e} Walker-Loud}, journal={Physical Review D}, year={2016}, volume={96}, pages={014504} }

Author(s): Bouchard, C; Chang, CC; Kurth, T; Orginos, K; Walker-Loud, A | Abstract: © 2017 American Physical Society. The Feynman-Hellmann theorem can be derived from the long Euclidean-time limit of correlation functions determined with functional derivatives of the partition function. Using this insight, we fully develop an improved method for computing matrix elements of external currents utilizing only two-point correlation functions. Our method applies to matrix elements of any external…

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