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arXiv · 1511.07090

Applications of the Feynman-Hellmann theorem in hadron structure

A. J. Chambers·R. Horsley·Y. Nakamura·H. Perlt·D. Pleiter·P. E. L. Rakow·G. Schierholz·A. Schiller·H. Stüben·R. D. Young·J. M. Zanotti
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Abstract

The Feynman-Hellmann (FH) relation offers an alternative way of accessing hadronic matrix elements through artificial modifications to the QCD Lagrangian. In particular, a FH-motivated method provides a new approach to calculations of disconnected contributions to matrix elements and high-momentum nucleon and pion form factors. Here we present results for the total nucleon axial charge, including a statistically significant non-negative total disconnected quark contribution of around $-5\%$ at an unphysically heavy pion mass. Extending the FH relation to finite-momentum transfers, we also present calculations of the pion and nucleon electromagnetic form factors up to momentum transfers of around 7-8 GeV$^2$. Results for the nucleon are not able to confirm the existence of a sign change for the ratio $\frac{G_E}{G_M}$, but suggest that future calculations at lighter pion masses will provide fascinating insight into this behaviour at large momentum transfers.

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A. J. Chambers, R. Horsley, Y. Nakamura, H. Perlt, D. Pleiter, P. E. L. Rakow, G. Schierholz, A. Schiller, H. Stüben, R. D. Young, J. M. Zanotti. 2015-11-23. Applications of the Feynman-Hellmann theorem in hadron structure. https://arxiv.org/abs/1511.07090

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