Lepton flavour violation in the constrained MSSM with natural neutrino mass hierarchy

We present predictions for mu --> egamma and tau --> mugamma in the CMSSM in which there is a natural hierarchy of neutrino masses resulting from the sequential dominance of three right-handed neutrinos. We perform a global analysis of this model in the (m(0), M-1/2) plane, assuming radiative electroweak symmetry breaking, and including all observed laboratory data. We confirm that a large (small) tau --> mugamma rate results from the dominant right-handed neutrino being the heaviest (lightest) one. We show that the mu--> egamma rate may determine the order of the subdominant neutrino Yukawa couplings in the flavour basis, but may also be sensitive to effects beyond the leading log and leading mass insertion approximations. We also show that the mu --> egamma rate is independent of theta(13), but measurement of this angle may determine a ratio of subdominant Yukawa couplings. (C) 2003 Elsevier Science B.V. All rights reserved.