Quartet S-wave p–d scattering in EFT Original Research Article

We present a power counting to include Coulomb effects in the three-nucleon system in a low-energy pionless effective field theory (EFT). With this power counting, the quartet S-wave proton–deuteron elastic scattering amplitude is calculated. The calculation includes next-to-leading order (NLO) Coulomb effects and next-to-next-to-leading order (N2LO) strong interaction effects, with an estimated theoretical error of ∼7%. The EFT results agree with potential model calculations and phase shift analysis of experimental data within the estimated errors.