Laser-modified Angular Distribution of Muon Decay
  We show theoretically that the angular distribution of decay rate of muon 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. The results suggest the muon may have internal structures instead structureless as in the standard model. 
Ai-Hua Liu, Shu-Min Li
hep-ph physics.atom-ph