Theoretical evaluation of solar proton-proton fusion reaction rate and its uncertainties

Abstract

The weak proton-proton fusion into a deuteron (2H) is the driving reaction in the energy production in the Sun, as well as similar main sequence stars. Its reaction rate in the solar interior is determined only theoretically. Here, we provide a new determination of the rate of this reaction in solar conditions S11(0), and analyze theoretical and experimental sources for uncertainties, using effective field theory of Quantum Chromodynamics without explicit pions at next-to-leading order. This prediction procedure is verified and validated using experimentally measured set of electromagnetic reactions, which we show to be analogous in their operator structure and properties to the weak sector, and are reproduced within the assessed theoretical uncertainty, using the same approach. We find an enhancement of S11 by 1−4% over the previously recommended value. This change reduces the calculated fluxes of neutrinos originating in 8B and 7Be nuclear reactions in the Sun, thus favoring higher abundances for metallic photospheric elements, in the tension between different composition determination, known as the “Solar Composition Problem”.