  We study the interplay between a soft muon Yukawa coupling generated
radiatively with the trilinear A-terms of the minimal supersymmetric standard
model (MSSM) and the anomalous magnetic moment of the muon. In the absence of a
tree-level muon Yukawa coupling the lightest smuon mass is predicted to be in
the range between 750 GeV and 2700 GeV at 2 sigma, if the bino mass M_1 is
below 1 TeV. Therefore, a detection of a smuon (in conjunction with a sub-TeV
bino) at the LHC would directly imply a non-zero muon Yukawa coupling in the
MSSM superpotential. Inclusion of slepton flavor mixing could in principle
lower the mass of one smuon-like slepton below 750 GeV. However, the
experimental bounds on radiative lepton decays instead strengthen the lower
mass bound, with larger effects for smaller M_1, We also extend the analysis to
the electron case and find that a light selectron close to the current
experimental search limit may prove the MSSM electron Yukawa coupling to be
non-zero.
