Related papers: Expectation values of four-quark operators in pion…
It is well-established for the vacuum case that in the limit of a large number of colors N_c the four-quark condensates factorize into products of the two-quark condensate. It is shown that in the combined large-N_c and linear-density…
We consider a U(5)-Nambu-Jona-Lasinio model with flavor-dependent couplings constants obtained from quark-antiquark polarization to investigate the role of the heavy quarks for light constituent quarks and mesons. A quantum mixing, due to…
The modern status of basic low energy QCD parameters is reviewed. It is demonstrated, that the recent data allows one to determine the light quark mass ratios with an accuracy 10-15%. The general analysis of vacuum condensates in QCD is…
In the framework of an extended Nambu--Jona-Lasinio model we are studying pion condensation in quark matter with an asymmetric isospin composition in a gravitational field of the static Einstein universe at finite temperature and chemical…
The relationship between mesonic correlations and quantum condensates in the quark matter phase diagram is explored within a quantum field theoretical approach of the Nambu and Jona-Lasinio (NJL) type. Mean-field values in the scalar meson…
Applying the Hellmann-Feynman theorem to a charged pion gas, the quark and gluon condensates at low isospin density are determined by precise pion properties. At intermediate density around $ f_\pi^2m_\pi$, from both the estimation for the…
We calculate the in-medium valence quark distribution of the pion immersed in a finite baryon density using the light-cone quark model. The medium-modified pion properties are obtained by using the constituent quark mass-dependent light…
It is shown that the spin polarized condensate appears in quark matter at high baryon density and low temperature due to the tensor-type four-point interaction in the Nambu-Jona-Lasinio-type model as a low energy effective theory of quantum…
The charge form factor and weak decay constant of the pion as well as the pion-quark coupling constant in symmetric nuclear matter are explored in the framework of the Nambu--Jona-Lasinio model, where the pion is described as a bound state…
Using the relation between the harmonic oscillator wave function and the light quark scattering form factor, the expectation values of colour-straight four-quark operators are evaluated and found to be directly proportional to the cubic…
The in-medium elastic scattering $qq\to qq, q\bar{q}\to q\bar{q}$ and $\bar{q}\bar{q}\to \bar{q}\bar{q}$ is calculated within the two-flavor Polyakov-loop-extended Nambu-Jona-Lasinio model. The integral and differential quark-quark…
We determine the ${\bar{q}}q$ condensate for quark masses from zero up to that of the strange quark within a phenomenologically successful modelling of continuum QCD by solving the quark Schwinger-Dyson equation. The existence of multiple…
Utilizing the in-medium Lorentz decomposition of operators generating QCD condensates we derive general constraints among the latter ones by the requirement of a smooth transition from medium to vacuum. In this way we relate the vacuum…
We investigate the possibility of charged pion condensation in the presence of parallel rotation and magnetic field within the Nambu--Jona-Lasinio model with quarks as the fundamental degrees of freedom. Previous study based on…
The properties of two-flavored massive Nambu--Jona-Lasinio model in (1+1)-dimensional spacetime are investigated in the presence of isospin and quark number chemical potentials. The consideration is performed in the large-$N_c$ limit, where…
Arguments in favor of a large magnitude ( at least two- three times bigger than its factorized value) of the mixed vacuum condensate $ \la \bar{q}G_{\mu\nu}^a G_{\mu\nu}^a q \ra$ are given. The analysis is based on the strict inequalities…
In light-cone quantization, the standard procedure to characterize the phases of a system by appropriate ground state expectation values fails. The light-cone vacuum is determined kinematically. We show that meaningful quantities which can…
The Nambu-Jona-Lasinio model is considered with flavor-dependent coupling constants $G_{ij} \left[ ( \bar{\psi} \lambda_i \psi ) ( \bar{\psi} \lambda_j \psi )+ ( \bar{\psi} i\gamma_5 \lambda_i \psi ) ( \bar{\psi} i \gamma_5\lambda_j \psi…
Results are presented from a numerical study of lattice QCD with gauge group SU(2) and two flavors of Wilson fermion at non-zero quark chemical potential mu >> T. Studies of the equation of state, the superfluid condensate, and the Polyakov…
The properties of two-flavored massless Nambu-Jona-Lasinio model in (1+1)-dimensional $R^1\times S^1$ spacetime with compactified space coordinate are investigated in the presence of isospin and quark number chemical potentials $\mu_I$,…