Nπ excited state contamination in nucleon 3-pt functions using ChPT
Pre-published on:
December 05, 2019
Published on:
August 27, 2020
Abstract
The Nπ-state contribution to nucleon 3-pt functions involving the pseudoscalar density P(x) and the time component A4(x) of the axial vector current are computed to LO in ChPT. In case of the latter the Nπ contribution is O(MN) enhanced compared to the single-nucleon ground state contribution. In addition, a relative sign in two terms of the Nπ contribution leads to an almost linear dependence on the operator insertion time, as it is observed in lattice data. In case of the pseudoscalar density the Nπ contribution is strongly dependent on the momentum transfer, leading to a distortion of the pseudoscalar nucleon form factor. Finally, the Nπ state contamination in the form factors result in a violation of the generalized Goldberger-Treiman relation as observed in various lattice calculations.
DOI: https://doi.org/10.22323/1.363.0078
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