Related papers: Nonlocal Condensates and Current-Current Correlato…
In the presence of the nontrivial QCD ground state or vacuum, nonlocal condensates are used to characterize the quark or gluon propagator, or other Green functions of higher order. In this paper, we wish to show that, by taking the large…
We propose to calculate the gluon condensate in lattice QCD in an indirect way by extracting it from the correlator of hadronic currents of heavy quarks. Moments (derivatives with respect to momentum at vanishing momentum) of the vector and…
It is essential to know the space-time structure of the nonlocal vacuum condensates for application to medium energy processes. Using the Dyson-Schwinger formalism in the rainbow approximation for the quark propagator, we study the nonlocal…
We examined the instanton contribution to the QCD configurations generated from lattice QCD for $N_F=0$, $N_F=2+1$ and $N_F=2+1+1$ dynamical quark flavors from two different and complementary approaches. First via the use of Gradient flow,…
Assuming the gluon field is well approximated by instanton configurations we derive a partition function and calculate the specific correlators. Namely, the heavy quark propagator and heavy quark-aniquark correlator with the account of the…
The interaction of light quarks and instanton liquid is analyzed at finite density of quark/baryon matter and in the phase of nonzero values of diquark (colour) condensate. It is shown that instanton liquid perturbation produced by such an…
In the framework of the Instanton Liquid Model we evaluate the heavy quark $\bar{Q}Q$ potential at nonzero temperature $T$. The potential has two components: contribution due to direct interaction with instantons, and the modification of…
The instanton-induced multiple events in high energy collisions are considered in nonperturbative quantum chromodynamics. Here we obtained unusual behaviour of ratio of correlation moments Hq for such processes which can be used for…
The influence of nonperturbative fields on instantons in quantum chromodynamics is studied. Nonperturbative vacuum is described in terms of nonlocal gauge invariant vacuum averages of gluon field strength.Effective action for instanton is…
Inspired by a recent proposal for a Higgs description of QCD we study the possible formation of a color-octet/flavor-octet quark-anti-quark condensate in the instanton liquid model. For this purpose we calculate two-point correlation…
We study, by numerical simulations on a lattice, the behaviour of the gauge-invariant quark-antiquark nonlocal condensates in the QCD vacuum with dynamical fermions. A determination is also done in the quenched approximation and the results…
QCD point-to-point correlation functions at distances .2-1 fm are very different for different channels, and they tell us a lot about inter-quark interactions. Recent studies based on experimental data, 'instanton liquid' approach and…
The main subject of these lectures is the Nonperturbative Wave Functions. We describe some nonperturbative methods (like QCD sum rules, dispersion relations, duality etc) in order to study this object. We also consider some applications of…
The proton form factors are reduced to vacuum correlators of 4 quark fields by assuming independent constituent quarks. The axial singlet quark and gluonic form factors are calculated in the instanton liquid model. A discussion of…
The correlator of vector heavy-quark currents at small q^2 is considered in the large-beta_0 limit. The leading IR renormalon ambiguity of the sum of the perturbative series is canceled by the UV renormalon ambiguity of the gluon…
We begin with the discussion of the relationship between the trace of the energy momentum tensor and the gluon condensate at finite temperatures. Using the recent numerical data from the simulations of lattice gauge theory for quantum…
We study correlation functions and Bethe Salpeter amplitudes for the scalar, the pseudoscalar and the tensor glueballs using an instanton-based model of the QCD vacuum. We consider both the pure gauge case and the situation for real QCD…
Gluon two- and three-point Green Functions computed in Landau gauge from the lattice show the existence of power corrections to the purely perturbative expressions, that can be explained through an Operator Product Expansion as the…
We study light quark interactions in the instanton liquid at finite quark/baryon number density analyzing chiral and diquark condensates and investigate the behaviors of quark dynamical mass and both condensates together with instanton…
Phenomenological results of equal time, point to point spatial correlation functions of hadronic currents are used to deduce the structure of the QCD vacuum. It is found that a model with only quark condensate is not adequate to explain the…