Constraints on $R$-parity violating interactions from $\mu\to e\gamma$
  The lepton number violating process $\mu\rightarrow e\gamma$ is used to study the lepton number violating couplings in MSSM extended by terms violating $R$-parity explicitly. Bounds are obtained for the products of $\lambda $- or $\lambda '$-type couplings. It is found that many of these limits are more stringent than the ones obtained previously. 
M. Chaichian, K. Huitu