LAUSR

Abstract We evaluated the charge radius of the first excited state of 13N with halo Effective Field Theory (hEFT) at the low energies. The halo effective field theory without pion is used to examine the halo nucleus bound state with a large S-wave scattering length. We built Lagrangian from the effective core and the valence proton of the fields and obtained the charge form factor at Leading–Order (LO). The charge radius at leading order for the first excited state of the proton halo nucleus, 13N, has been estimated as r c = 2.52 fm. This result is without any finite-size contributions included from the core and the proton. If we consider the contributions of the charge radius of the proton and the core, the result will be [ r C ] 13 N * = 5.85 fm.