We numerically study QCD with a single
quark flavour on the lattice probing predictions
from effective field theories that are equivalent to
minimal super-symmetric Yang-Mills theory in
the large $N_c$ limit.
The hadronic spectrum including excited states is
analysed using one gauge coupling and several
physical volumes and fermion masses. We use the
LapH method and also compute disconnected
diagrams.
Lattice simulations with an odd number of Wilson
fermions give rise to regions of configuration
space with a negative fermionic weight entailing a
sign problem. We perform a detailed analysis on
the spectrum of the Wilson-Dirac operator and
report on observed cases of a negative fermion
determinant in our ensembles.