1,263 research outputs found
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
Three-body dispersion-relation N/D equations for the coupled decay channels ppbar (J^{PC}=0^{-+}) --> pi^0 pi^0 pi^0, eta pi^0 pi^0, eta eta pi^0, K Kbar pi^0
During several years the data on different channels ppbar (J^{PC}=0^{-+}) -->
3 mesons presented by Crystal Barrel Collaboration were successfully analyzed
by extracting the leading amplitude singularities - pole singularities - with
the aim to obtain information about two-meson resonances. But these analyses do
not take into account three-body final state interactions (FSI) in an
explicitly correct way. This paper is devoted to the consideration of this
problem.Comment: 16 pages, no figure
Bianchi Type V Viscous Fluid Cosmological Models in Presence of Decaying Vacuum Energy
Bianchi type V viscous fluid cosmological model for barotropic fluid
distribution with varying cosmological term is investigated. We have
examined a cosmological scenario proposing a variation law for Hubble parameter
in the background of homogeneous, anisotropic Bianchi type V space-time.
The model isotropizes asymptotically and the presence of shear viscosity
accelerates the isotropization. The model describes a unified expansion history
of the universe indicating initial decelerating expansion and late time
accelerating phase. Cosmological consequences of the model are also discussed.Comment: 10 pages, 3 figure
On the non-Abelian Stokes theorem for SU(2) gauge fields
We derive a version of non-Abelian Stokes theorem for SU(2) gauge fields in
which neither additional integration nor surface ordering are required. The
path ordering is eliminated by introducing the instantaneous color orientation
of the flux. We also derive the non-Abelian Stokes theorem on the lattice and
discuss various terms contributing to the trace of the Wilson loop.Comment: Latex2e, 0+14 pages, 3 figure
Observing Long Colour Flux Tubes in SU(2) Lattice Gauge Theory
We present results of a high statistics study of the chromo field
distribution between static quarks in SU(2) gauge theory on lattices of volumes
16^4, 32^4, and 48^3*64, with physical extent ranging from 1.3 fm up to 2.7 fm
at beta=2.5, beta=2.635, and beta=2.74. We establish string formation over
physical distances as large as 2 fm. The results are tested against Michael's
sum rules. A detailed investigation of the transverse action and energy flux
tube profiles is provided. As a by-product, we obtain the static lattice
potential in unpreceded accuracy.Comment: 66 pages, 29 figures, uuencoded latex file with epsfigures (450 K),
supplementary full colour figures are available via ftp, CERN-TH.7413/94
(extended version
Gribov Copies in the Maximally Abelian Gauge and Confinement
We fix lattice gauge fields to the Maximally Abelian gauge in both
three and four dimensions. We extract the corresponding fields and
monopole current densities and calculate separately the confining string
tensions arising from these fields and monopole `condensates'. We
generate multiple Gribov copies and study how the fields and monopole
distributions vary between these different copies. As expected, we find
substantial variations in the number of monopoles, their locations and in the
values of the field strengths. The string tensions extracted from
`extreme' Gribov copies also differ but this difference appears to be no more
than about 20\%. We also directly compare the fields of different Gribov
copies. We find that on the distance scales relevant to confinement the
and monopole fluxes that disorder Wilson loops are highly correlated between
these different Gribov copies. All this suggests that while there is indeed a
Gribov copy problem the resulting ambiguity is, in this gauge and for the study
of confinement, of limited importance.Comment: 31 pages LaTeX plus 5 PostScript figures. Uses epsf.sty.
Self-unpacking, uuencoded tar-compressed fil
Quark-gluonium content of the scalar-isoscalar states f_0(980), f_0(1300), f_0(1500), f_0(1750), f_0(1420 ^{+150}_{- 70}) from hadronic decays
On the basis of the decay couplings f_0 -> \pi\pi, K\bar K, \eta\eta,
\eta\eta', which had been found before, in the study of analytical
(IJ^{PC}=00^{++})-amplitude in the mass range 450-1900 MeV, we analyse the
quark-gluonium content of resonances f_0(980), f_0(1300), f_0(1500), f_0(1750)
and the broad state f_0(1420 ^{+ 150}_{-70}). The K-matrix technique used in
the analysis makes it possible to evaluate the quark-gluonium content both for
the states with switched-off decay channels (bare states, f^{bare}_0) and the
real resonances. We observe significant change of the quark-gluonium
composition in the evolution from bare states to real resonances, that is due
to the mixing of states in the transitions f_0(m_1)-> real mesons-> f_0(m_2)
responsible for the decay processes as well. For the f_0(980), the analysis
confirmed the dominance of q\bar q component thus proving the n\bar n/s\bar s
composition found in the study of the radiative decays. For the mesons
f_0(1300), f_0(1500) and f_0(1750), the hadronic decays do not allow one to
determine uniquely the n\bar n, s\bar s and gluonium components providing
relative pecentage only. The analysis shows that the broad state f_0(1420 ^{+
150}_{-70}) can mix with the flavour singlet q\bar q component only, that is
consistent with gluonium origin of the broad resonance.Comment: 20 pages, LaTeX, 10 PostScript figures, epsfig.st
The two-pion spectra for the reaction \pi^- p -> \pi^0\pi^0 n at 38 GeV/c pion momentum and combined analysis of the GAMS, Crystal Barrel and BNL data
We perform the K-matrix analysis of meson partial waves with IJ^{PC}
=00^{++}, 10^{++}, 02^{++}, 12^{++} basing on GAMS data on \pi^-p -> \pi^0\pi^0
n, \eta\eta n, \eta\eta' n together with BNL data on \pi^-p -> K\bar K n and
Crystal Barrel data on p\bar p (at rest) -> \pi^0\pi^0\pi^0, \pi^0\eta\eta,
\pi^0\pi^0\eta. The positions of the amplitude poles (physical resonances) are
determined as well as the positions of the K-matrix poles (bare states) and the
values of bare state couplings to two-meson channels. Nonet classification of
the determined bare states is discussed.Comment: LaTex, 15 pages and 10 figure
Systematization of tensor mesons and the determination of the glueball
It is shown that new data on the -resonances in the mass
range MeV support the linearity of the -trajectories,
where is the radial quantum number of quark--antiquark state. In this way
all vacancies for the isoscalar tensor -mesons in the range up to 2450
MeV are filled in. This allows one to fix the broad -state with
MeV and MeV as the lowest tensor glueball. PACS
numbers: 14.40.-n, 12.38.-t, 12.39.-MkComment: 10 pages, 1 figur
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