Fernández Pérez, Luis AntonioFernández Álvarez-Estrada, RamónSánchez Gómez, J. L.2023-06-212023-06-2119830556-282110.1103/PhysRevD.27.2656https://hdl.handle.net/20.500.14352/65023© 1983 The American Physical Society. We thank Dr. E. Oset for a useful discussion on pions in nuclear matter. Partial financial support from the Comision Asesora de Investigacion Cientifica (Spain) is gratefully acknowledged.In this paper, proton decay in a large nucleus is studied in the framework of SU(5) grand unification theory (GUT). By using a method based upon the Green s-function technique of many-body physics, nuclear effects on spectator and pole terms are computed. The decay width in the nucleus is found to be practically the same as in free space. However, nuclear effects are of considerable importance concerning the positron spectrum. A densitycorrelation expansion is introduced which is useful for carrying out a systematic study of nuclear effects in proton decay in a large nucleus. The method presented here can be easily extended to other GUT's or supersymmetric GUT's.engjournal articlehttp://dx.doi.org/10.1103/PhysRevD.27.2656http://journals.aps.org/open access53Astronomy and astrophysicsPhysicsparticles and fieldsFísica (Física)22 Física