scholarly journals Determination of the quantum part of the truly nonperturbative Yang-Mills vacuum energy density in covariant gauge QCD

2000 ◽  
Vol 62 (7) ◽  
Author(s):  
V. Gogohia ◽  
Gy. Kluge
Keyword(s):  
Energy Density ◽  
Vacuum Energy ◽  
Vacuum Energy Density ◽  
Yang Mills ◽  
Covariant Gauge

CHIRAL QCD VACUUM ENERGY DENSITY IN THE ZERO MODES ENHANCEMENT QUANTUM MODEL

2000 ◽  
Vol 15 (01) ◽  
pp. 45-64 ◽  
Author(s):  
V. GOGOHIA ◽  
H. TOKI ◽  
T. SAKAI ◽  
Gy. KLUGE
Keyword(s):  
Energy Density ◽  
Vacuum Energy ◽  
Chiral Limit ◽  
Dyson Equation ◽  
Chiral Condensate ◽  
Vacuum Energy Density ◽  
Quantum Model ◽  
Yang Mills ◽  
Qcd Vacuum ◽  
Order Of Magnitude

Using the effective potential approach for composite operators we have formulated the quantum model of the QCD vacuum. It is based on the existence and importance of the nonperturbative q-4-type dynamical, topologically nontrivial excitations of the gluon field configurations (due to self-interaction of the massless gluons only). The QCD vacuum is found to be stable since the vacuum energy density has no imaginary part. The Yang–Mills (YM) part of the vacuum energy density is always negative and depends on a finite scale at which nonperturbative effects become important. The quark part of the vacuum energy density depends in addition on the constant of integration of the corresponding Schwinger–Dyson equation. The value of the above-mentioned scale is determined from the bounds for the pion decay constant in the chiral limit. Our value for the chiral QCD vacuum energy density is one order of magnitude bigger than the instanton based models can provide while a fair agreement with recent phenomenological and lattice results for the chiral condensate is obtained.

scholarly journals LOCAL CONTRIBUTION OF A QUANTUM CONDENSATE TO THE VACUUM ENERGY DENSITY

2003 ◽  
Vol 18 (10) ◽  
pp. 683-690 ◽  
Author(s):  
GIOVANNI MODANESE
Keyword(s):  
Energy Density ◽  
Vacuum Energy ◽  
Casimir Effect ◽  
Landau Equation ◽  
Vacuum Energy Density ◽  
Negative Effects ◽  
Ginzburg Landau ◽  
Physical Conditions ◽  
Local Contribution ◽  
Gravitational Vacuum

We evaluate the local contribution gμνL of coherent matter with Lagrangian density L to the vacuum energy density. Focusing on the case of superconductors obeying the Ginzburg–Landau equation, we express the relativistic invariant density L in terms of low-energy quantities containing the pairs density. We discuss under which physical conditions the sign of the local contribution of the collective wave function to the vacuum energy density is positive or negative. Effects of this kind can play an important role in bringing the local changes in the amplitude of gravitational vacuum fluctuations — a phenomenon reminiscent of the Casimir effect in QED.

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