  Understanding small neutrino masses in type II seesaw models with TeV scale
SM triplet Higgs bosons requires that its coupling with the standard model
Higgs doublet H be dialed down to be order eV to KeV, which is a fine-tuning by
a factor of $10^{-11}-10^{-8}$ with respect to the weak scale. We present a
SUSY extension of the type II seesaw model where this dimensionful small
coupling is radiatively induced, thus making its smallness natural. This model
has an exotic vector-like quark doublet which contains a quark X with electric
charge 5/3 and a top partner t'. We discuss in details the phenomenology of the
model paying special attention to the consequences of the interactions of the
the exotic heavy quarks and the scalars of the model. Implications for
neutrinoless double beta decay and for the LHC experiments are discussed in
detail. Remarkably, in this model both the seesaw triplet and the heavy quarks
can manifest at colliders in a host of different signatures, including some
that significantly differ from those of the minimal models. Depending on the
choice of the hierarchy of couplings, the decay of the heavy quarks and of the
seesaw triplet may be subject to bounds that can be tighter or looser than the
bounds from standard LHC searches. Furthermore we point out a new
short-distance contribution to neutrinoless double beta decay mediated by the
simultaneous propagation of the type II triplet and exotic fermions. Remarkably
this contribution to the neutrinoless double beta decay is parametrically quite
independent from the scale of the generated neutrino mass.
