442 research outputs found
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
Chiral Symmetry Breaking with Scalar Confinement
Spontaneous chiral symmetry breaking is accepted to occur in low energy
hadronic physics, resulting in the several successful theorems of PCAC. On the
other hand scalar confinement is suggested both by the spectroscopy of hadrons
and by the string picture of confinement. However these two evidences are
apparently conflicting, because chiral symmetry breaking requires a chiral
invariant coupling to the quarks, say a vector coupling like in QCD. Here we
reformulate the coupling of the quarks to the string, and we are able to comply
with chiral symmetry breaking, using scalar confinement. The results are quite
encouraging.Comment: 4 pages, 5 figures, contribution to the XXXVIIIth Rencontres de
Moriond QCD and High Energy Hadronic Interaction
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
Dynamical origin and the pole structure of X(3872)
The dynamical mechanism of channel coupling with the decay channels is
applied to the case of coupled charmonium - states with .
A pole analysis is done and the production cross section is calculated
in qualitative agreement with experiment. The sharp peak at the
threshold and flat background are shown to be due to Breit-Wigner resonance,
shifted by channel coupling from the original position of 3954 MeV for the
, state. A similar analysis, applied to the , ,
, , allows us to associate the first one with the observed
J=2 and explains the destiny of .Comment: 5 pages, 4 figures. Accepted for publication in Phys. Rev. Let
Gluonic correlation length from spin-dependent potentials
The vacuum gluonic correlation length is extracted from recent lattice data
on spin-dependent interquark potentials in heavy quarkonia. It is shown that
the data are consistent with extremely small values of the correlation length,
Tg<0.1 fm.Comment: LaTeX2e, 6 pages, uses jetpl.cls (included), version to appear in
JETP Let
Chiral Lagrangian with confinement from the QCD Lagrangian
An effective Lagrangian for the light quark in the field of a static source
is derived systematically using the exact field correlator expansion. The
lowest Gaussian term is bosonized using nonlocal colorless bosonic fields and a
general structure of effective chiral Lagrangian is obtained containing all set
of fields. The new and crucial result is that the condensation of scalar
isoscalar field which is a usual onset of chiral symmetry breaking and is
constant in space-time, assumes here the form of the confining string and
contributes to the confining potential, while the rest bosonic fields describe
mesons with the q\bar q quark structure and pseudoscalars play the role of
Nambu-Goldstone fields. Using derivative expansion the effective chiral
Lagrangian is deduced containing both confinement and chiral effects for
heavy-light mesons. The pseudovector quark coupling constant is computed to be
exactly unity in the local limit,in agreement with earlier large N_c arguments.Comment: LaTeX2e, 17 page
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
Interaction of Wilson loops in confining vacuum
Nonperturbative and perturbative interaction mechanisms of Wilson loops in
gluodynamics are studied within the background field formalism. The first one
operates when distance between minimal surfaces of the loops is small and may
be important for sea quark effects and strong decay processes. The second
mechanism -- perturbative interaction in nonperturbative confining background
is found to be physically dominant for all loop configurations characteristic
of scattering process. It reduces to perturbative gluon exchanges at small
distances, while at larger distances it corresponds to the t-channel exchange
of (reggeized) glueball states.
Comparison to other approaches is made and possible physical applications are
discussed.Comment: LaTeX, 25 pages, 5 EPS-figure
Effects of perturbative exchanges in a QCD-string model
The QCD-string model for baryons derived by Simonov and used for the
calculation of baryon magnetic moments in a previous paper is extended to
include also perturbative gluon and meson exchanges. The mass spectrum of the
baryon multiplet is studied. For the meson interaction either the pseudoscalar
or pseudovector coupling is used. Predictions are compared with the
experimental data. Besides these exchanges the influence of excited quark
orbitals on the baryon ground state are considered by performing a multichannel
calculation. The nucleon-Delta splitting increases due to the mixing of higher
quark states while the baryon magnetic momenta decrease. The multichannel
calculation with perturbative exchanges is shown to yield reasonable magnetic
moments while the mass spectrum is close to experiment.Comment: 37 pages Revtex with 2 figures, to be published in Phys. Atom. Nucl.
dedicated to the 70th Birthday of Yu. A. Simono
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