3 Neutrinos and the Cosmos

Gustavo Branco’s distinguished contributions include leading ones to neutrino physics, CP violation, and leptogenesis. To plan the future experimental exploration of some of the physics to which Prof. Branco has contributed, and which is near and dear to his heart, several studies focusing on neutrinos have been carried out. I would like to report on one of these, sponsored by four Divisions of the American Physical Society [1]. This study’s aim was to develop a coherent and effective strategy for the U.S. role in a global neutrino program. It was intended that the U.S. role complement and cooperate with the efforts in Europe and Asia [2]. We now have beautiful and compelling evidence that neutrinos have nonzero masses. This discovery has raised a number of interesting questions. The APS Multi-Divisional study has grouped these according to three themes. The first theme is —