%0 Journal Article
%A Krebs, Hermann
%A Epelbaum, E.
%A Meißner, U.-G.
%T Box diagram contribution to the axial two-nucleon current
%J Physical review / C
%V 101
%N 5
%@ 2469-9985
%C Woodbury, NY
%I Inst.
%M FZJ-2021-00167
%P 055502
%D 2020
%X Recently, we have worked out the axial two-nucleon current operator to leading one-loop order in chiral effective field theory using the method of unitary transformation. Our final expressions, however, differ from the ones derived by the JLab-Pisa group using time-ordered perturbation theory [Phys. Rev. C 93, 015501 (2016); Phys. Rev. C 93, 049902(E) (2016); Phys. Rev. C 95, 059901(E) (2017)]. In this paper we consider the box diagram contribution to the axial current and demonstrate that the results obtained using the two methods are unitary equivalent at the Fock-space level. We adjust the unitary phases by matching the corresponding two-pion exchange nucleon-nucleon potentials and rederive the box diagram contribution to the axial current operator following the approach of the JLab-Pisa group, thereby reproducing our original result. We provide a detailed information on the calculation of the box diagram including the relevant intermediate steps in order to facilitate a clarification of this disagreement.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000530027200005
%R 10.1103/PhysRevC.101.055502
%U https://juser.fz-juelich.de/record/889262