$pp$ Solar Neutrinos at DARWIN

Understand

The DARWIN collaboration recently argued that DARWIN (DARk matter WImp search with liquid xenoN) can collect, via neutrino--electron scattering, a large, useful sample of solar $pp$-neutrinos, and measure their survival probability with sub-percent precision.

• We explore the physics potential of such a sample in more detail.
• We estimate that, with 300 ton-years of data, DARWIN can also measure, with the help of current solar neutrino data, the value of $\sin^2\theta_{13}$, with the potential to exclude $\sin^2\theta_{13}=0$ close to the three-sigma level.
• We explore in some detail how well DARWIN can constrain the existence of a new neutrino mass-eigenstate $\nu_4$ that is quasi-mass-degenerate with $\nu_1$ and find that DARWIN's sensitivity supersedes that of all current and near-future searches for new, very light neutrinos.