Improved Effective Action for Light Quarks Beyond Chiral Limit

We propose an improvement of the Diakonov-Petrov Effective Action on the basis of the Lee-Bardeen results for the quark determinant in the instanton field. This Improved Effective Action provides proper account of the current quark masses, which is particularly important for strange quarks. This Action is successfully tested by the calculations of the quark condensate, the masses of the pseudoscalar meson octet and by axial-anomaly low-energy theorems.Comment: 15 pages, 1 figure, Latex. New references were adde

Current mass dependence of the quark condensate and the constituent quark mass

We discuss the current mass dependence of the basic quantities of the quark models -- constituent quark mass M and quark condensate i. The framework of the consideration is QCD instanton vacuum model.Comment: 7 pages, 2 figures, talk presented at the International Symposium on Hadrons and Nuclei, Seoul, February 20-22, 200

Heavy and light quarks in the instanton vacuum

Assuming the gluon field is well approximated by instanton configurations we derive a light quarks determinant and calculate its contribution to the specific heavy quarks correlators -- namely, the heavy quark propagator and heavy quark-aniquark correlator, receiving the instanton generated light-heavy quarks interaction terms contributions. With these knowledge we calculate the light quark contribution to the interaction between heavy quarks, which might be essential for the properties of a few heavy quarks systems.Comment: Talk given at the workshop "Hadron Nuclear Physics 2011", APCTP, Pohang, Republic of Korea, Feb. 21-24, 2011. The workshop proceedings will be published at the EPJ web of conferences (http://www.epj-conferences.org/

Two-Loop Effective Action for Theories with Fermions

On the basis of a new approach proposed in our previous work we develope a formalism for calculating of the effective action for some models containing fermion fields. This method allows us to calculate the fermionic part of the effective action (up to two-loop level) properly. The two-loop contribution to the effective potential for the Nambu-Jona-Lasinio model is calculated and is shown to vanish.Comment: 23 pages, late

Dynamical gluon mass in the instanton vacuum model

We are considering the modifications of gluon properties in Instanton Liquid Model (ILM) for the QCD vacuum. Re-scattering of a gluons on an instantons leads to the dynamical momentum-dependent gluon mass $M_g(q).$ First, we considered scalar "gluon", since there are no zero-modes problem and found its dynamical mass $M_s(q)$. At the typical phenomenological values of the average instanton size $\rho=1/3\,\,fm$ and average inter-instanton distance $R=1\,\, fm$ we got $M_s(0)=256\,\,MeV$. Further, we extended this approach to the real vector gluon with careful consideration of zero-modes and got $M^2_g(q)=2M^2_s(q).$ This modification of the gluon in the instanton media might be important for the heavy quarkonium physics at least