mu -capture and ortho-para transitions in the muonic molecule pp mu

The capture of a muon by protons at different hydrogen densities is considered. More precise values of gamma -factors for ortho- and para- states of the muonic molecule pp mu are obtained: 2 gamma /sub 0 /=1009+or-0.001 and 2 gamma /sub p/=1.143+or-0.001. Relativistic effects are taken into account in the muonic molecule, and the rate of ortho-para transitions lambda /sub op/=(7.1+or-1.2)*10/sup 4/ s/sup -1 /, caused by these effects, is calculated. With this value of lambda /sub op/ the mu -capture rate in liquid hydrogen is found to be Lambda /sub c/=(490+or-10) s/sup -1/ that is in agreement with the value Lambda /sub c/=460+or-20 s/sup -1/ recently measured by the Saclay- CERN-Bologna collaboration.