Solar Proton Burning Process Revisited within a Covariant Model Based on the Bethe-Salpeter Formalism

A covariant model based on the Bethe-Salpeter formalism is proposed for investigating the solar proton burning process $pp\to De^+\nu_e$ and the near-threshold deuteron disintegration via electromagnetic and weak interactions. Results of numerical calculations of the energy dependence of relevant cross sections and the astrophysical low-energy cross section factor $S_{pp}$ of the proton burning process are presented. Our results confirm previous canonical values, and the energy dependence of the $S_{pp}$ factor is rather close to phenomenological extrapolations commonly adopted in computations of solar nuclear reaction rates.