Nuclear Production and Analytic Attenuation of Energetic MeV Solar Dark Matter

We propose a solar production mechanism of MeV dark matter to overcome the energy threshold in direct detection experiments. In particular, the proton and deuteron fussion to ${}^3\mathrm{H}\mathrm{e}$ of the $pp$ chain that produces energetic neutrino and gamma photon with 5.5$$MeV of energy release can also produce a pair of dark matter particles. Besides, we establish an analytical formalism of using the Boltzmann equation to study the solar attenuation effect on the produced dark matter flux. The projected sensitivity is illustrated with Argon target at the DarkSide-LowMass experiment.