Neutrino physics with the PTOLEMY project: active neutrino properties and the light sterile case

31 pags., 7 figs.
The PTOLEMY project aims to develop a scalable design for a Cosmic Neutrino Background (CNB) detector, the first of its kind and the only one conceived that can look directly at the image of the Universe encoded in neutrino background produced in the first second after the Big Bang. The scope of the work for the next three years is to complete the conceptual design of this detector and to validate with direct measurements that the non-neutrino backgrounds are below the expected cosmological signal. In this paper we discuss in details the theoretical aspects of the experiment and its physics goals. In particular, we mainly address three issues. First we discuss the sensitivity of PTOLEMY to the standard neutrino mass scale. We then study the perspectives of the experiment to detect the CNB via neutrino capture on tritium as a function of the neutrino mass scale and the energy resolution of the apparatus. Finally, we consider an extra sterile neutrino with mass in the eV range, coupled to the active states via oscillations, which has been advocated in view of neutrino oscillation anomalies. This extra state would contribute to the tritium decay spectrum, and its properties, mass and mixing angle, could be studied by analyzing the features in the beta decay electron spectrum.
Work supported by the Italian grant 2017W4HA7S “NAT-NET: Neutrino and Astroparticle Theory Network” (PRIN 2017) funded by the Italian Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR); by the Spanish grants ENE2016-76755-R, SEV-2014-0398 and FPA2017- 85216-P (AEI/FEDER, UE), PROMETEO/2018/165 (Generalitat Valenciana), María de Maeztu Unit of Excellence CIEMAT - Particle Physics (MDM-2015-0509) and the Red Consolider MultiDark FPA2017-90566-REDC; by the Vetenskapsrådet (Swedish Research Council) through contract No. 638-2013-8993; by the Simons Foundation, USA (#377485) and John Templeton Foundation, USA (#58851); and by the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie individual Grant Agreement No. 796941.