11 research outputs found
Baryon-Baryon Potentials on the Lattice
The interaction of spatially extended heavy baryons is investigated in the
framework of lattice QCD with dynamical quarks. It is shown that the expected
dipole forces have a very short range and that the baryon-antibaryon
interaction is more attractive than the baryon-baryon interaction. Sea quarks
play a minor important role.Comment: 8 pages, uuencoded postscript file; Physics Letters B, in pres
Towards a Topological Mechanism of Quark Confinement
We report on new analyses of the topological and chiral vacuum structure of
four-dimensional QCD on the lattice. Correlation functions as well as
visualization of monopole currents in the maximally Abelian gauge emphasize
their topological origin and gauge invariant characterization. The
(anti)selfdual character of strong vacuum fluctuations is reveiled by
smoothing. In full QCD, (anti)instanton positions are also centers of the local
chiral condensate and quark charge density. Most results turn out generically
independent of the action and the cooling/smoothing method.Comment: 14 pages, Contribution to YKIS9
Distribution of fermionic and topological observables on the lattice
We analyze the topological and fermionic vacuum structure of four-dimensional
QCD on the lattice by means of correlators of fermionic observables and
topological densities. We show the existence of strong local correlations
between the topological charge and monopole density on the one side and the
quark condensate, charge and chiral density on the other side. Visualization of
individual gauge configurations demonstrates that instantons (antiinstantons)
carry positive (negative) chirality, whereas the quark charge density
fluctuates in sign within instantons.Comment: 10 pages, 5 eps figures, to appear in Phys. Lett.
Meson-meson interactions -- from static to dynamic valence quarks
A method for the extraction of an effective meson-meson potential from Green
functions, which can be obtained from a lattice simulation, is presented.
Simulations are carried out for compact QED and QCD in four dimensions using
the quenched approximation and the hopping parameter expansion. In a further
study, a heavy-light meson is considered employing a conjugate gradient
algorithm for the light propagators. Due to the Pauli exclusion principle, the
results for QED indicate the existence of a hard core, but for QCD there is
strong attraction at small meson distances.Comment: 4 pages, uuencoded gziped postscript file, contribution to
LATTICE'95, Melbourne, Australia (list of authors completed
String Breaking in Lattice Quantum Chromodynamics
The separation of a heavy quark and antiquark pair leads to the formation of
a tube of flux, or string, which should break in the presence of light
quark-antiquark pairs. This expected zero temperature phenomenon has proven
elusive in simulations of lattice QCD. We present simulation results that show
that the string does break in the confining phase at nonzero temperature.Comment: 11 pages RevTeX, including 4 encapsulated Postscript figures.
version2: minor corrections to reference
Quark zero modes in intersecting center vortex gauge fields
The zero modes of the Dirac operator in the background of center vortex gauge
field configurations in and are examined. If the net flux in D=2
is larger than 1 we obtain normalizable zero modes which are mainly localized
at the vortices. In D=4 quasi-normalizable zero modes exist for intersecting
flat vortex sheets with the Pontryagin index equal to 2. These zero modes are
mainly localized at the vortex intersection points, which carry a topological
charge of . To circumvent the problem of normalizability the
space-time manifold is chosen to be the (compact) torus \T^2 and \T^4,
respectively. According to the index theorem there are normalizable zero modes
on \T^2 if the net flux is non-zero. These zero modes are localized at the
vortices. On \T^4 zero modes exist for a non-vanishing Pontryagin index. As
in these zero modes are localized at the vortex intersection points.Comment: 20 pages, 4 figures, LaTeX2e, references added, treatment of ideal
vortices on the torus shortene
On the fermionic signature of the lattice monopoles
We consider fermions in the field of static monopole-like configurations in
the Euclidean space-time. In all the cases considered there exists an infinite
number of zero modes, labeled by frequency i\omega. The existence of such modes
is a manifestation of instability of the vacuum in the presence of the
monopoles and massless fermions. In the Minkowski space the corresponding
phenomenon is well known and is a cornerstone of the theory of the magnetic
catalysis. Moreover, the well known zero mode of Jackiw and Rebbi corresponds
to the limiting case, \omega = 0. We provide arguments why the chiral
condensate could be linked to the density of the monopoles in the infrared
cluster. A mechanism which can naturally explain the equivalence of the
critical temperatures for the deconfinement and chiral transitions, is
proposed. We discuss possible implications for the phenomenology of the lattice
monopoles.Comment: 8 pages, RevTeX 4. An extended version, to be published in the
Physical Review