Bounds on fourth generation induced lepton flavour violating double insertions in supersymmetry

We derive bounds on leptonic double mass insertions of the type δi4lδ4jl in four generational MSSM, using the present limits on li→lj+γ. Two main features distinguish the rates of these processes in MSSM4 from MSSM3: (a) tanβ is restricted to be very small ≲3 and (b) the large masses for the fourth generation leptons. In spite of small tanβ, there is an enhancement in amplitudes with LLRR (δi4llδ4jrr) type insertions which pick up the mass of the fourth generation lepton, mτ′. We find these bounds to be at least two orders of magnitude more stringent than those in MSSM3.