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arXiv · 1809.10180

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
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Abstract

The magnetic form factors of $^2$H, $^3$H, and $^3$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 $Δ$ intermediate states that have recently been constructed in configuration space. The $A\,$=$\,$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 $Δ$ 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$^{-1}$. 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.

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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. 2018-09-26. Local chiral interactions and magnetic structure of few-nucleon systems. https://doi.org/10.1103/physrevc.99.034005

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