Elastic p−C12 scattering calculations using a cluster effective field theory

The elastic p-¹²C scattering at low energies is studied by using a cluster effective field theory (EFT), where the low-lying resonance states (s1/2, p3/2, d5/2) of ¹³N are treated as pertinent degrees of freedom. The low-energy constants of the Lagrangian are expressed in terms of the Coulomb-modified effective range parameters, which are determined to reproduce the experimental data for the differential cross sections. The resulting theoretical predictions agree very well with the experimental data. The resulting theory is shown to give us almost identical phase shifts as obtained from the R-matrix approach and predict the experimental analyzing power data. The role of the ground state of ¹³N below the threshold and the next-to-leading order in the EFT power counting are also discussed.