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arXiv · 0906.1800

Electromagnetic Currents and Magnetic Moments in $χ$EFT

S. Pastore·L. Girlanda·R. Schiavilla·M. Viviani·R. B. Wiringa
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Abstract

A two-nucleon potential and consistent electromagnetic currents are derived in chiral effective field theory ($χ$EFT) at, respectively, $Q^{2}$ (or N$^2$LO) and $e Q$ (or N$^3$LO), where $Q$ generically denotes the low-momentum scale and $e$ is the electric charge. Dimensional regularization is used to renormalize the pion-loop corrections. A simple expression is derived for the magnetic dipole ($M1$) operator associated with pion loops, consisting of two terms, one of which is determined, uniquely, by the isospin-dependent part of the two-pion-exchange potential. This decomposition is also carried out for the $M1$ operator arising from contact currents, in which the unique term is determined by the contact potential. Finally, the low-energy constants (LEC's) entering the N$^2$LO potential are fixed by fits to the $np$ S- and P-wave phase shifts up to 100 MeV lab energies.

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S. Pastore, L. Girlanda, R. Schiavilla, M. Viviani, R. B. Wiringa. 2009-07-24. Electromagnetic Currents and Magnetic Moments in $χ$EFT. https://doi.org/10.1103/physrevc.80.034004

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