Lattice QCD evaluation of the Compton amplitude employing the Feynman-Hellmann theorem

QCDSF-UKQCD-CSSM Collaboration

Research output: Contribution to journalArticlepeer-review


The forward Compton amplitude describes the process of virtual photon scattering from a hadron and provides an essential ingredient for the understanding of hadron structure. As a physical amplitude, the Compton tensor naturally includes all target mass corrections and higher twist effects at a fixed virtuality, Q2. By making use of the second-order Feynman-Hellmann theorem, the nucleon Compton tensor is calculated in lattice QCD at an unphysical quark mass across a range of photon momenta 3≲Q2≲7 GeV2. This allows for the Q2 dependence of the low moments of the nucleon structure functions to be studied in a lattice calculation for the first time. The results demonstrate that a systematic investigation of power corrections and the approach to parton asymptotics is now within reach.
Original languageEnglish
Article number114505
Pages (from-to)1-18
Number of pages18
JournalPhysical Review D
Issue number11
Publication statusPublished - 8 Dec 2020


  • hep-lat
  • hep-ph
  • hep-th
  • nucl-th


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