98 research outputs found
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/
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 First, we
considered scalar "gluon", since there are no zero-modes problem and found its
dynamical mass . At the typical phenomenological values of the average
instanton size and average inter-instanton distance we got . Further, we extended this approach to the real
vector gluon with careful consideration of zero-modes and got
This modification of the gluon in the instanton media
might be important for the heavy quarkonium physics at least
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
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