TY  - JOUR
AU  - Krebs, Hermann
AU  - Epelbaum, E.
AU  - Meißner, U.-G.
TI  - Box diagram contribution to the axial two-nucleon current
JO  - Physical review / C
VL  - 101
IS  - 5
SN  - 2469-9985
CY  - Woodbury, NY
PB  - Inst.
M1  - FZJ-2021-00167
SP  - 055502
PY  - 2020
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000530027200005
DO  - DOI:10.1103/PhysRevC.101.055502
UR  - https://juser.fz-juelich.de/record/889262
ER  -