A. Galante

New proposal for numerical simulations of theta-vacuum-like systems.

We propose a new approach to perform numerical simulations of theta-vacuum-like systems, test it in two analytically solvable models, and apply it to CP3. The main new ingredient in our approach is the method used to compute the probability distribution function of the topological charge at theta=0. We do not get unphysical phase transitions (flattening behavior of the free energy density) and reproduce the exact analytical results for the order parameter in the whole theta range within a few percent.

Parity and CT Realization in QCD

We show that an essential assumption in the Vafa and Wittens theorem on P and CT realization in vector-like theories, the existence of a free energy density in Euclidean space in the presence of any external hermitian symmetry breaking source, does not apply if the symmetry is spontaneously broken. The assumption that the free energy density is well defined requires the previous assumption that the symmetry is realized in the vacuum. Even if Vafa and Wittens conjecture is plausible, actually a theorem is still lacking.

Critical Behavior of CP^1 at theta = pi, Haldane's Conjecture and the Universality Class

Using an approach to analyze the theta dependence of systems with a theta term we recently proposed, the critical behavior of CP(10 at theta=pi is studied. We find a region outside the strong coupling regime where Haldanes conjecture is verified. The critical line, however, does not belong to the universality class of the Wess-Zumino-Novikov-Witten model at topological coupling k=1 since it shows continuously varying critical exponents.

θdependence of theCP9model

We apply to the

Three and two colours finite density QCD at strong coupling: A new look

CP^9

Fermionic effective action and the phase structure of noncompact quantum electrodynamics in 2 + 1 dimensions

model two recently proposed numerical techniques for simulation of systems with a theta term. The algorithms, successfully tested in the strong coupling limit, are applied to the weak coupling region. The results agree and errors have been evaluated and are at % level. The results scale well with the renormalization group equation and show that, for

Rigorous arguments against current wisdoms in finite density QCD

CP^9

Critical behavior of the Schwinger model with Wilson fermions

in presence of a theta term, CP symmetry is spontaneously broken at

Finite density fat QCD

\theta=\pi

BARYONIC THERMAL FLUCTUATIONS IN FINITE TEMPERATURE QCD

in the continuum limit.