Phase structure of thermal lattice QCD with N_f=2 twisted mass Wilson fermions

We present numerical results for the phase diagram of lattice QCD at finite temperature in the formulation with twisted mass Wilson fermions and a tree-level Symanzik-improved gauge action. Our simulations are performed on lattices with temporal extent N_τ=8, and lattice coupling βranging from strong coupling to the scaling domain. Covering a wide range in the space spanned by the lattice coupling βand the hopping and twisted mass parameters κand μ, respectively, we obtain a comprehensive picture of the rich phase structure of the lattice theory. In particular, we verify the existence of an Aoki phase in the strong coupling region and the realisation of the Sharpe-Singleton scenario at intermediate couplings. In the weak coupling region we identify the phase boundary for the physical finite temperature phase transition/crossover. Its shape in the three-dimensional parameter space is consistent with Creutz's conjecture of a cone-shaped thermal transition surface.