928 research outputs found
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
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
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
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
Nonperturbative mechanisms of strong decays in QCD
Three decay mechanisms are derived systematically from the QCD Lagrangian
using the field correlator method. Resulting operators contain no arbitrary
parameters and depend only on characteristics of field correlators known from
lattice and analytic calculations. When compared to existing phenomenological
models, parameters are in good agreement with the corresponding fitted values.Comment: 12 pages, latex2
Confinement and chiral symmetry breaking in heavy-light quark systems
Assuming a Gaussian approximation for the QCD gluodynamics, all the
nonperturbative physics can be encoded into two parameters: the gluon
correlation length and the gluon condensate . These parameters are
sufficient in order to describe the heavy-heavy quark nonperturbative
interaction. In this work we adopt the same framework in order to study
heavy-light bound states in the non-recoil limit. Spontaneous chiral symmetry
breaking and a confining chiral non-invariant interaction emerge quite
naturally. The gap equation is solved and discussed. In particular a relation
between the light quark condensate and is derived. The energy spectrum
for the bound state equation is evaluated and commented.Comment: 15 pages, 2 figures, elsart.st
Dynamics of quark-gluon plasma from Field correlators
It is argued that strong dynamics in the quark-gluon plasma and bound states
of quarks and gluons is mostly due to nonperturbative effects described by
field correlators. The emphasis in the paper is made on two explicit
calculations of these effects from the first principles: one analytic using
gluelump Green's functions and another using independent lattice data on
correlators. The resulting hadron spectra are investigated in the range T_c < T
< 2T_c. The spectra of charmonia, bottomonia, light s-sbar mesons, glueballs
and quark-gluon states calculated numerically are in general agreement with
lattice MEM data. The possible role of these bound states in the thermodynamics
of quark-gluon plasma is discussed.Comment: Revised version with new comments and references and corrected tables
VII-IX; 34 pages + 6 figure
Quarkonia and Quark Drip Lines in Quark-Gluon Plasma
We extract the - potential by using the thermodynamic quantities
obtained in lattice gauge calculations. The potential is tested and found to
give dissociation temperatures that agree well with those from lattice gauge
spectral function analysis. Using such a - potential, we examine the
quarkonium states in a quark-gluon plasma and determine the `quark drip lines'
which separate the region of bound color-singlet states from the
unbound region. The characteristics of the quark drip lines severely limit the
region of possible bound states with light quarks to temperatures
close to the phase transition temperature. Bound quarkonia with light quarks
may exist very near the phase transition temperature if their effective quark
mass is of the order of 300-400 MeV and higher.Comment: 24 pages, 13 figures, in LaTe
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