Improved limit on the branching ratio of μ−→e+ conversion on titanium

Abstract The SINDRUM II spectrometer at PSI is used in searches for μ → e conversion in muonic atoms. Here we report on a search for the charge-changing μ − → e + conversion on titanium. The measurements yielded the new upper limits Γ ( μ − Ti → e + Ca GS )/ Γ ( μ − Ti capture) −12 (90% CL) for the ground state transition and Γ ( μ − Ti → e + Ca GDR )/ Γ ( μ − Ti capture) −11 (90% CL) for a giant dipole resonance excitation with both a mean energy and a width of 20 MeV. These results improve on our previous best limits by a factor of 2.5.