We take a new look at the neutron radiative capture by a deuteron at thermal energy with the pionless effective field theory (EFT(π /)) approach. We present in detail the calculation of nd → 3 Hγ amplitudes for incoming doublet and quartet channels leading to the formation of a triton fully in the projection method based on the cluster-configuration space approach. In the present work, we consider all possible one-body and two-body photon interaction diagrams. In fact, additional diagrams that make significant changes in the results of the calculation of the total cross section in the nd → 3 Hγ process are included in this study. The properly normalized triton wave function is calculated and taken into consideration. We compare the cross section of the dominant magnetic M1-transition of nd → 3 Hγ up to next-to-next-to-leading order N 2 LO with the results of the previous model-dependent theoretical calculations and experimental data. The more acceptable results for cross section σ (2) tot = 0.297 (LO) + 0.124 (NLO) + 0.048 (N 2 LO) = [0.469 ± 0.033] mb show order by order convergence and cutoff independence. No three-body currents are needed to renormalize observables up to N 2 LO in this process.
The parity-violating Lagrangian of the weak nucleon-nucleon (N N ) interaction in the pionless effective field theory (EFT(/ π)) approach contains five independent unknown low-energy coupling constants (LECs). The photon asymmetry with respect to neutron polarization in np → dγ A Then, we evaluate photon asymmetry with respect to the neutron polarization a nd γ and the photon asymmetry in relation to deuteron polarization A nd γ in nd → 3 Hγ process. We finally compare our EFT(/ π) photon asymmetries results with the experimental values and the previous calculations based on the DDH model.PACS numbers:
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