Local chiral interactions and magnetic structure of few-nucleon systems
R. Schiavilla🇺🇸 · A. Baroni🇺🇸 · S. Pastore🇺🇸 · M. Piarulli🇺🇸 · L. Girlanda🇮🇹 · A. Kievsky🇮🇹 · A. Lovato🇮🇹 · L.E. Marcucci🇮🇹 · Steven C. Pieper🇺🇸 · M. Viviani🇮🇹 · R.B. Wiringa🇺🇸
The magnetic form factors of H, H, and He, deuteron photodisintegration cross sections at low energies, and deuteron threshold electrodisintegration cross sections at backward angles in a wide range of momentum transfers, are calculated with the chiral two-nucleon (and three-nucleon) interactions including intermediate states that have recently been constructed in configuration space. The =3 wave functions are obtained from hyperspherical-harmonics solutions of the Schrödinger equation. The electromagnetic current includes one- and two-body terms, the latter induced by one- and two-pion exchange (OPE and TPE, respectively) mechanisms and contact interactions. The contributions associated with intermediate states are only retained at the OPE level, and are neglected in TPE loop (tree-level) corrections to two-body (three-body) current operators. Expressions for these currents are derived and regularized in configuration space for consistency with the interactions. The low-energy constants that enter the contact few-nucleon systems. The predicted form factors and deuteron electrodisintegration cross section are in excellent agreement with experiment for momentum transfers up to 2--3 fm. However, the experimental values for the deuteron photodisintegration cross section are consistently underestimated by theory, unless use is made of the Siegert form of the electric dipole transition operator. A complete analysis of the results is provided, including the clarification of the origin of the aforementioned discrepancy.