1,032 research outputs found
Deconfinement transition for nonzero baryon density in the Field Correlator Method
Deconfinement phase transition due to disappearance of confining
colorelectric field correlators is described using nonperturbative equation of
state. The resulting transition temperature at any chemical
potential is expressed in terms of the change of gluonic condensate
and absolute value of Polyakov loop , known from
lattice and analytic data, and is in good agreement with lattice data for
GeV. E.g. GeV for
respectively.Comment: 8 pages, 1 figure, LaTeX2e; some typos correcte
Dynamics of confined gluons
Propagation of gluons in the confining vacuum is studied in the framework of
the background perturbation theory, where nonperturbative background contains
confining correlators. Two settings of the problem are considered. In the first
the confined gluon is evolving in time together with static quark and antiquark
forming the one-gluon static hybrid. The hybrid spectrum is calculated in terms
of string tension and is in agreement with earlier analytic and lattice
calculations. In the second setting the confined gluon is exchanged between
quarks and the gluon Green's function is calculated, giving rise to the Coulomb
potential modified at large distances. The resulting screening radius of 0.5 fm
presents a serious problem when confronting with lattice and experimental data.
A possible solution of this discrepancy is discussed.Comment: 17 pages, no figures; v2: minor numerical changes in the tabl
The static interaction at small distances and OPE violating terms
Nonperturbative contribution to the one-gluon exchange produces a universal
linear term in the static potential at small distances . Its role in the resolution of long--standing
discrepancies in the fine splitting of heavy quarkonia and improved agreement
with lattice data for static potentials is discussed, as well as implications
for OPE violating terms in other processes.Comment: Latex, 5 pages, to be published in JETP Let
The matrix Hamiltonian for hadrons and the role of negative-energy components
The world-line (Fock-Feynman-Schwinger) representation is used for quarks in
arbitrary (vacuum and valence gluon) field to construct the relativistic
Hamiltonian. After averaging the Green's function of the white system
over gluon fields one obtains the relativistic Hamiltonian, which is matrix in
spin indices and contains both positive and negative quark energies. The role
of the latter is studied in the example of the heavy-light meson and the
standard einbein technic is extended to the case of the matrix Hamiltonian.
Comparison with the Dirac equation shows a good agreement of the results. For
arbitrary system the nondiagonal matrix Hamiltonian components are
calculated through hyperfine interaction terms. A general discussion of the
role of negative energy components is given in conclusion.Comment: 29 pages, no figure
Analytic calculation of field-strength correlators
Field correlators are expressed using background field formalism through the
gluelump Green's functions. The latter are obtained in the path integral and
Hamiltonian formalism. As a result behaviour of field correlators is obtained
at small and large distances both for perturbative and nonperturbative parts.
The latter decay exponentially at large distances and are finite at x=0, in
agreement with OPE and lattice data.Comment: 28 pages, no figures; new material added, misprints correcte
Decay constants of the heavy-light mesons from the field correlator method
Meson Green's functions and decay constants in different
channels are calculated using the Field Correlator Method. Both,
spectrum and , appear to be expressed only through universal
constants: the string tension , , and the pole quark masses.
For the -wave states the calculated masses agree with the experimental
numbers within MeV. For the and mesons the values of are equal to 210(10) and 260(10) MeV, respectively, and their ratio
=1.24(3) agrees with recent CLEO experiment. The values MeV are obtained for the , , and mesons
with the ratio =1.19(2) and =1.14(2). The decay constants
for the first radial excitations as well as the decay constants
in the vector channel are also calculated. The difference of
about 20% between and , and directly follows
from our analytical formulas.Comment: 37 pages, 10 tables, RevTeX
Glueballs, gluerings and gluestars in the d=2+1 SU(N) gauge theory
The 3d gluodynamics which governs the large T quark gluon plasma is studied
in the framework of the field correlator method. Field correlators and spacial
string tension are derived through the gluelump Green's functions. The glueball
spectrum is calculated both in C=-1 as well as in C=+1 sectors, and multigluon
bound states in the form of "gluon rings" and "gluon stars" are computed
explicitly. Good overall agreement with available lattice data is observed.Comment: 19 page
Current correlators in QCD: OPE versus large distance dynamics
We analyse the structure of current-current correlators in coordinate space
in large limit when the corresponding spectral density takes the form of
an infinite sum over hadron poles. The latter are computed in the QCD string
model with quarks at the ends, including the lowest states, for all channels.
The corresponding correlators demonstrate reasonable qualitative agreement with
the lattice data without any additional fits. Different issues concerning the
structure of the short distance OPE are discussed.Comment: LaTeX, 25 pages, 13 figure
Baryon magnetic moments in the effective quark Lagrangian approach
An effective quark Lagrangian is derived from first principles through
bilocal gluon field correlators. It is used to write down equations for
baryons, containing both perturbative and nonperturbative fields. As a result
one obtains magnetic moments of octet and decuplet baryons without introduction
of constituent quark masses and using only string tension as an input. Magnetic
moments come out on average in reasonable agreement with experiment, except for
nucleons and . The predictions for the proton and neutron are shown
to be in close agreement with the empirical values once we choose the string
tension such to yield the proper nucleon mass. Pionic corrections to the
nucleon magnetic moments have been estimated. In particular, the total result
of the two-body current contributions are found to be small. Inclusion of the
anomalous magnetic moment contributions from pion and kaon loops leads to an
improvement of the predictions.Comment: 24 pages Revte
Test of the QCD vacuum with the sources in higher representations
Recent accurate measurement by G.Bali of static potentials between sources in
various SU(3) representations provides a crucial test of the QCD vacuum and of
different theoretical approaches to the confinement. In particular, the Casimir
scaling of static potentials found for all measured distances implies a strong
suppression of higher cumulants and a high accuracy of the Gaussian stochastic
vacuum. Most popular models are in conflict with these measurements.Comment: LaTeX, 7 page
- …