776 research outputs found
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
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
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
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
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
QCD string in light-light and heavy-light mesons
The spectra of light-light and heavy-light mesons are calculated within the
framework of the QCD string model, which is derived from QCD in the Wilson loop
approach. Special attention is payed to the proper string dynamics that allows
us to reproduce the straight-line Regge trajectories with the inverse slope
being 2\pi\sigma for light-light and twice as small for heavy-light mesons. We
use the model of the rotating QCD string with quarks at the ends to calculate
the masses of several light-light mesons lying on the lowest Regge trajectories
and compare them with the experimental data as well as with the predictions of
other models. The masses of several low-lying orbitally and radially excited
heavy--light states in the D, D_s, B, and B_s meson spectra are calculated in
the einbein (auxiliary) field approach, which has proven to be rather accurate
in various calculations for relativistic systems. The results for the spectra
are compared with the experimental and recent lattice data. It is demonstrated
that an account of the proper string dynamics encoded in the so-called string
correction to the interquark interaction leads to an extra negative
contribution to the masses of orbitally excited states that resolves the
problem of the identification of the D(2637) state recently claimed by the
DELPHI Collaboration. For the heavy-light system we extract the constants
\bar\Lambda, \lambda_1, and \lambda_2 used in Heavy Quark Effective Theory
(HQET) and find good agreement with the results of other approaches.Comment: RevTeX, 42 pages, 7 tables, 7 EPS figures, uses epsfig.sty, typos
corrected, to appear in Phys.Rev.
Pentaquarks in the Jaffe-Wilczek approximation
The masses of , and pentaquarks are
evaluated in a framework of both the Effective Hamiltonian approach to QCD and
spinless Salpeter using the Jaffe--Wilczek diquark approximation and the string
interaction for the diquark--diquark--antiquark system. The pentaquark masses
are found to be in the region above 2 GeV. That indicates that the Goldstone
boson exchange effects may play an important role in the light pentaquarks. The
same calculations yield the mass of pentaquark 3250 MeV
and pentaquark 6509 MeV.Comment: 14 pages, 2 tables, LaTeX2e. References correcte
Di-Pion Decays of Heavy Quarkonium in the Field Correlator Method
Mechanism of di-pion transitions in
bottomonium and charmonium is studied with the use of the chiral
string-breaking Lagrangian allowing for the emission of any number of
and not containing fitting parameters. The transition amplitude
contains two terms, , where first term (a) refers to subsequent one-pion
emission: and second term
(b) refers to two-pion emission: . The one-parameter formula for the di-pion mass
distribution is derived, (phase space) , where
. The
parameter dependent on the process is calculated, using SHO wave
functions and imposing PCAC restrictions (Adler zero) on amplitudes a,b. The
resulting di-pion mass distributions are in agreement with experimental data.Comment: 62 pages,8 tables,7 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
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