  The Mott transition is observed experimentally in materials that are
magnetically frustrated so that long-range order does not hide the Mott
transition at finite temperature. The Hubbard model on the triangular lattice
at half-filling is a paradigmatic model to study the interplay of interactions
and frustration on the normal-state phase diagram. We use the dynamical cluster
approximation with continuous time auxiliary field quantum Monte Carlo to solve
this model for 1, 4, 6, 12, and 16 site clusters with detailed analysis
performed for the 6 site cluster. We show that a) for every cluster there is an
inflection point in the double occupancy as a function of interaction, defining
a Widom line that extends above the critical point of the first-order Mott
transition; b) the presence of this line and the cluster size dependence argue
for the observability of the Mott transition at finite temperature in the
thermodynamic limit; c) the loss of spectral weight in the metal to Mott
insulator transition as a function of temperature and for strong interactions
is momentum dependent, the hallmark of a pseudogap. That pseudogap spans a
large region of the phase diagram near the Mott transition.

Strongly Correlated Electrons;Computational Physics