CHINESE ACAD SCI,INST HIGH ENERGY PHYS,BEIJING,PEOPLES R CHINA
; UNIV IOANNINA,DIV THEORET PHYS,IOANNINA,GREECE
; UNIV TUBINGEN,INST THEORET PHYS,W-7400 TUBINGEN 1,GERMANY
; UNIV VALENCIA,CSIC,CTR MIXTO,IFIC,E-46100 BURJASSOT,SPAIN
Coherent and incoherent (mu-, e-) conversion in nuclei is studied within the framework of several theories which violate flavour lepton number. A useful approach is followed which allows a factorization of the conversion widths into nuclear factors and other factors which depend only on the elementary process. The nuclear factors are evaluated in a wide range of nuclei allowing simple calculations of the conversion rates throughout the periodic table for a given theory with a minimum of work in the elementary sector. The coherent conversion is found to dominate the process. The results obtained modify appreciable previous results in the literature, particularly in the incoherent process.