1,237 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
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
Product Integral Formalism and Non-Abelian Stokes Theorem
We make use of the properties of product integrals to obtain a surface
product integral representation for the Wilson loop operator. The result can be
interpreted as the non-abelian version of Stokes' theorem.Comment: Latex; condensed version of hep-th/9903221, to appear in Jour. Math.
Phy
A short distance quark-antiquark potential
Leading terms of the static quark-antiquark potential in the background
perturbation theory are reviewed, including perturbative, nonperturbative and
interference ones. The potential is shown to describe lattice data at short
quark-antiquark separations with a good accuracy.Comment: 4 pages, 2 figures, talk at the NPD-2002 Conference, December 2-6,
ITEP, Moscow, references update
Diquark and triquark correlations in the deconfined phase of QCD
We use the non-perturbative Q\bar Q potential at finite temperatures derived
in the Field Correlator Method to obtain binding energies for the lowest
eigenstates in the Q\bar Q and QQQ systems (Q=c,b). The three--quark problem is
solved by the hyperspherical method. The solution provides an estimate of the
melting temperature and the radii for the different diquark and triquark bound
states. In particular we find that J/\psi and ground states survive up to
T \sim 1.3 T_c, where T_c is the critical temperature, while the corresponding
bottomonium states survive even up to higher temperature, T \sim 2.2 T_c.Comment: 11 pages, 1 figure; published versio
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