Twisted mass quarks and the phase structure of lattice QCD F. Farchioni, R. Frezzotti, K. Jansen, I. Montvay, G. C. Rossi, E. Scholz, A. Shindler, N. Ukita, C. Urbach and I. Wetzorke Eur. Phys. J. C, 39 4 (2005) 421-433 Published online: 15 February 2005 DOI: 10.1140/epjc/s2004-02078-9