Laser-Assisted Muon Decay

We show theoretically that the muon lifetime can be changed dramatically by embedding the decaying muon in a strong linearly polarized laser field. Evaluating the $S$-matrix elements taking all electronic multiphoton processes into account we find that a ${\mathrm{CO}}_2$ laser with an electric field amplitude of ${10}^6\mathrm{V}{\mathrm{cm}}^{-1}$ results in an order of magnitude shorter lifetime of the muon. We also analyze the dependencies of the decay rate on the laser frequency and intensity.

Figure 1

The photon-number ($l$) resolved decay rate ($W_l$) in the rest frame of the muon, numerically calculated according to Eq. (6) for a Nd:YAG laser ($\hslash \omega =1.17\mathrm{eV}$) with an electric field amplitude of ${10}^7\mathrm{V}{\mathrm{cm}}^{-1}$ (left-hand panel) and a ${\mathrm{CO}}_2$ laser ($\hslash \omega =0.117\mathrm{eV}$) with an electric field amplitude of ${10}^6\mathrm{V}{\mathrm{cm}}^{-1}$ (right-hand panel).

Figure 2

The laser-modified muon lifetime as a function of the laser field amplitude strength. The results for a Nd:YAG laser ($\hslash \omega =1.17\mathrm{eV}$) (solid line) and a ${\mathrm{CO}}_2$ laser ($\hslash \omega =0.117\mathrm{eV}$) (dashed line) are indicated.