Exploring the phase structure of lattice QCD with twisted mass quarks
  The phase structure of zero temperature twisted mass lattice QCD is investigated. We find strong metastabilities in the plaquette observable when the untwisted quark mass sweeps across zero. 
F.Farchioni, C.Urbach, R.Frezzotti, K.Jansen, I.Montvay, G.C.Rossi,   E.E.Scholz, A.Shindler, N.Ukita, I.Wetzorke