DETAILED STUDY OF THE INCOHERENT MU(-)-]E(-) CONVERSION RATE - ELIMINATION OF SPURIOUS CONTAMINATIONS FROM THE 1(-) CONTRIBUTION

The incoherent matrix elements of the exotic (mu(-),e(-)) conversion i n nuclei process are studied in detail for a set of nuclei throughout the periodic table in the context of the quasiparticle random phase ap proximation (RPA). The contaminations, usually inserted in the 1(-) RP A excitation modes (the most important incoherent mu --> e conversion channel), are removed by explicitly constructing the purely spurious c enter-sf-mass state. We found that mostly the lowest-lying 1(1)(-) sta te is affected by the use of non-self-consistent single-particle energ ies and a truncated model space in the RPA. To a good approximation we can regard this state as fully spurious and treat the other states as the physical ones. The elimination of the spuriousness requires a dif ferent renormalization of the interaction. This allows us to reproduce the excitation spectrum, needed to calculate reliably the incoherent matrix elements of the mu --> e process, with realistic forces (Bonn p otential) which cannot be achieved with the contaminated wave function s. We focus on the investigation of the incoherent rate of Ti-48, from which the best upper limit for the flavor number violation has been e xtracted, and Pb-208, which is currently used in the SINDRUM II experi ment at PSI.