Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Nonperturbative Calculation of Basic Chiral QCD Parameters within
  Dynamical Equations Approach to QCD at Low Energies   Basic chiral QCD parameters (the pion decay constant, the quark and gluon
condensates, the dynamically generated quark mass, etc) as well as the vacuum
energy density have been calculated from first principles within a recently
proposed dynamical equations approach to QCD at low energies. The zero modes
enhancement (ZME) model of quark confinement and dynamical chiral symmetry
breaking (DCSB) based on the solution to the Schwinger-Dyson (SD) equation for
the quark propagator in the infrared (IR) domain was used for this purpose.
There are only two independent quantities by means of which calculations should
be done within our approach. Our unique input data was chosen to be the pion
decay constant in the chiral limit given by the chiral perturbation theory at
the hadronic level (CHPTh). Phenomenological estimates of these quantities, as
well as the vacuum energy density, are in good agreement with our numerical
results. The nonperturbative vacuum structure which emerges from the ZME model,
appears to be well suited to describe quark confinement, DCSB,
current-effective (dynamical)-constituent, as well as constituent-valence quark
transformations, the Okubo-Zweig-Iizuka (OZI) rule, dimensional transmutation,
etc. The importance of the instanton-type fluctuations in the true QCD vacuum
for the ZME model is also emphasized. This allows to predict new, more
realistic values for the vacuum energy density (apart from the sign, by
definition, the bag constant) and the gluon condensate.

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The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
19
The categories of this paper are: eess