Phase diagram of twisted mass lattice QCD
- Physics Department, Box 351560, University of Washington, Seattle, Washington 98195 (United States)
We use the effective chiral Lagrangian to analyze the phase diagram of two-flavor twisted mass lattice QCD as a function of the normal and twisted masses, generalizing previous work for the untwisted theory. We first determine the chiral Lagrangian including discretization effects up to next-to-leading order (NLO) in a combined expansion in which m{sub {pi}}{sup 2}/(4{pi}f{sub {pi}}){sup 2}{approx}a{lambda} (a being the lattice spacing, and {lambda}={lambda}{sub QCD}). We then focus on the region where m{sub {pi}}{sup 2}/(4{pi}f{sub {pi}}){sup 2}{approx}(a{lambda}){sup 2}, in which case competition between leading and NLO terms can lead to phase transitions. As for untwisted Wilson fermions, we find two possible phase diagrams, depending on the sign of a coefficient in the chiral Lagrangian. For one sign, there is an Aoki phase for pure Wilson fermions, with flavor and parity broken, but this is washed out into a crossover if the twisted mass is nonvanishing. For the other sign, there is a first order transition for pure Wilson fermions, and we find that this transition extends into the twisted mass plane, ending with two symmetrical second order points at which the mass of the neutral pion vanishes. We provide graphs of the condensate and pion masses for both scenarios, and note a simple mathematical relation between them. These results may be of importance to numerical simulations.
- OSTI ID:
- 20705623
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 70, Issue 9; Other Information: DOI: 10.1103/PhysRevD.70.094029; (c) 2004 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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