  We study QCD with 2 and 3 flavours of colour-sextet quarks. The 2-flavour
theory is a candidate Walking Technicolor theory. Since we are attempting to
distinguish whether this theory is walking or conformal, we also study the
3-flavour theory, which is believed to be conformal, for comparison. We
simulate lattice QCD with 2 and 3 flavours of colour-sextet staggered quarks at
finite temperatures to determine the scales of confinement and chiral-symmetry
breaking from the positions of the deconfinement and chiral-symmetry
restoration transitions. Unlike the case with fundamental quarks, these
transitions are far apart. For 2 flavours the values of beta=6/g^2 for both
transitions increase as Ta is decreased from 1/4 to 1/6 to 1/8, as expected for
a theory whose coupling runs to smaller values as the lattice spacing is
decreased. However, for the chiral transition, the increase in beta between
Ta=1/4 and Ta=1/6 is much larger than the increase between Ta=1/6 and Ta=1/8.
This suggests that between Ta=1/4 and Ta=1/6 we are at strong coupling where
the theory is effectively quenched, while between Ta=1/6 and Ta=1/8 we are
emerging into the weak coupling regime. It will require even smaller Ta values
to determine whether the running of the chiral-transition coupling is
controlled by asymptotic freedom and the theory walks, or if it reaches a
non-zero limit when the transition becomes a bulk transition and the theory is
conformal. The 3 flavour case at Ta=1/4 and Ta=1/6 behaves similarly to the 2
flavour case. Since this theory is expected to be conformal, the interpretation
that we are seeing strong-coupling behaviour, inaccessible from the
weak-coupling limit (continuum) is the most likely interpretation.
