Search for geo-neutrinos and rare nuclear processes with Borexino

Borexino was designed to measure solar neutrinos in the MeV or sub-MeV energy range. The unprecedented radiopurity of the detector has allowed the detection of geo-neutrinos and the determination of competitive limits on the rate of rare or forbidden processes. In this paper, we review the basic principle of neutrinos and antineutrinos detection in Borexino and we describe the results of the geo-neutrinos measurements and their implications. Then we summarize the search for Borexino events correlated with gamma ray bursts and for axion induced signals, and the limits achieved on Pauli forbidden transitions and on the electron charge conservation.