Charge and magnetic properties of three-nucleon systems in pionless effective field theory

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© 2018 American Physical Society. A method to calculate the form factor for an external current with nonderivative coupling for the three-body system in an effective field theory (EFT) of short-range interactions is shown. Using this method, the point charge radius of He3 is calculated to next-to-next-to-leading order (NNLO) in pionless EFT (EFT(π/)), and the magnetic moment and magnetic radius of H3 and He3 are calculated to next-to-leading order (NLO). For the He3 charge and magnetic form factors Coulomb interactions are ignored. The He3 point charge radius is given by 1.74(4) fm at NNLO. This agrees well with the experimental He3 point charge radius of 1.7753(54) fm [Angeli and Marinova, At. Data Nucl. Data Tables 99, 69 (2013)10.1016/j.adt.2011.12.006]. The H3 (He3) magnetic moment in units of nuclear magnetons is found to be 2.92(35) (-2.08(25)) at NLO in agreement with the experimental value of 2.979 (-2.127). For H3 (He3) the NLO magnetic radius is 1.78(11) fm (1.85(11) fm), which agrees with the experimental value of 1.840(182) fm (1.965(154) fm) [Sick, Prog. Part. Nucl. Phys. 47, 245 (2001)10.1016/S0146-6410(01)00156-9]. The fitting of the low-energy constant L1 of the isovector two-body magnetic current and the consequences of Wigner-SU(4) symmetry for the three-nucleon magnetic moments are also discussed.