Geo-neutrinos: theoretical aspects

Abstract

Geo-neutrinos emitted by heat-producing elements (U, Th, K) can uniquely probe Earth interior. Their fluxes present large and correlated uncertainties. Handling them is difficult but necessary, if one wants to quantify how future data can reduce errors. In this context, we propose a systematic approach in terms of covariance matrices. Our method is based on the fact that all the relevant geo-neutrino observables and constraints can be expressed as linear functions of the U, Th, and K abundances in Earth's reservoirs. We briefly discuss the construction of a tentative Geo-Neutrino Source Model (GNSM), describing U, Th, K abundances in Earth reservoirs, based on available geochemical data and reliable geophysical models (when possible), and on supplementary assumptions and hypotheses (when unavoidable). Starting from the GNSM, we make predictions about several experiments (“forward approach”) and show how future data can constrain the error matrix of the model (“backward approach”). This method may provide a useful template for current and future studies, and for evaluating the impact and the global consistency of prospective geo-neutrino measurements and Earth models.