Isotope dependence of particle-decay rates of muonic molecular ions (d3,4He?) J=1 below (d?)1s-3,4He threshold

Abstract

Rates of particle-emitting decay of the resonant state of the muonic molecular ion (dHeμ)J=1 lying below the (dμ)1s-He threshold can decay to the d-Heμ scattering state. The resonant state is estimated by scattering calculations with the non-adiabatic coupled-rearrangement-channel method. Strong isotope dependence of the decay rates of (d3Heμ)J=1 and (d4Heμ)J=1 is predicted, though the calculated radiative decay rates of the states are almost the same. In (d3Heμ)J=1, the particle decay width is three times larger than the radiative decay width, while the two types of decay widths are almost the same in (d4Heμ)J=1. This results in a strong hindrance of the branching ratio of the radiative decay of (d3Heμ)J=1 compared with the case of (d4Heμ)J=1. This is consistent with a recent observation of the radiative decay of the two molecular states.