D. Gómez Dumm

Chiral quark models with nonlocal separable interactions at finite temperature and chemical potential

\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\tau}}\ensuremath{\pi}\ensuremath{\pi}\ensuremath{\pi}{\ensuremath{\nu}}_{\ensuremath{\tau}}

Characteristics of the chiral phase transition in nonlocal quark models

decays are analyzed within the framework of the resonance effective theory of QCD. We work out the relevant Lagrangian that describes the axial-vector current hadronization contributing to these processes, in particular the local

Chiral phase transition in a covariant nonlocal NJL model

{a}_{1}(1260)\ensuremath{-}\ensuremath{\rho}(770)

Covariant nonlocal chiral quark models with separable interactions

-Goldstone interactions. The new coupling constants are constrained by imposing the asymptotic behavior of the corresponding spectral function within QCD. Hence we compare the theoretical framework with the experimental data, obtaining a good quality fit from the ALEPH spectral function and branching ratio. We also get values for the mass and on-shell width of the

Meson properties at finite temperature in a three flavor nonlocal chiral quark model with Polyakov loop

{a}_{1}(1260)

Flavor-changing neutral currents in 331 models

resonance. In this way we are able to provide the structure functions that have been measured by OPAL and CLEO-II and we find an excellent agreement.

Hybrid stars within a covariant, nonlocal chiral quark model

Chiral quark models with nonlocal covariant separable interactions at finite temperature and chemical potential are investigated. We develop a formalism in which the different quark properties are evaluated taking into account the analytic structure of the quark propagator. In this framework we study the chiral restoration phase transition for several definite nonlocal regulators, including that arising within the instanton liquid picture. We find that in all cases the chiral transition is of first order for low values ofT, turning into a smooth crossover at a certain ‘‘end point.’’ Using model parameters which lead to the physical pion mass and decay constant, we find for the position of this ‘‘end point’’ the values ( TE ,m E)’(60‐70,180‐210) MeV. We also discuss the special relevance of the first poles of the quark propagator.

Resonance Chiral Lagrangian analysis of τ − → η ( ′ ) π − π 0 ν τ

The characteristics of the chiral phase transition are analyzed within the framework of chiral quark models with nonlocal interactions in the mean-field approximation. In the chiral limit, we develop a semianalytic framework that allows us to explicitly determine the phase transition curve, the position of the critical points, some relevant critical exponents, etc. For the case of finite current quark masses, we show the behavior of various thermodynamical and chiral response functions across the phase transition.

Deconfinement and chiral restoration in non-local PNJL models at zero and imaginary chemical potential

Abstract The properties of the chiral phase transition at finite temperature and chemical potential are investigated within a nonlocal covariant extension of the Nambu–Jona-Lasinio model based on a separable quark–quark interaction. We consider both the situation in which the Minkowski quark propagator has poles at real energies and the case where only complex poles appear. In the literature, the latter has been proposed as a realization of confinement. In both cases, the behaviour of the physical quantities as functions of T and μ is found to be quite similar. In particular, for low values of T the chiral transition is always of first order and, for finite quark masses, at certain “end point” the transition turns into a smooth crossover. In the chiral limit, this “end point” becomes a “tricritical” point. Our predictions for the position of these points are similar, although somewhat smaller, than previous estimates. Finally, the relation between the deconfining transition and chiral restoration is also discussed.