3,761 research outputs found
Strong Coupling Model for String Breaking on the Lattice
A model for SU(n) string breaking on the lattice is formulated using strong
coupling ideas. Although necessarily rather crude, the model gives an explicit
picture of string breaking in the presence of dynamical quarks as a mixing
phenomenon that involves the string state and a two-meson state. A careful
analysis, within the model, of the Wilson loop shows that the evolution of the
mixing angle as a function of separation may obscure the expected crossover
effect. If a sufficiently extensive mixing region exists then an appropriate
combination of transition amplitudes can help in revealing the effect.
The sensitivity of the mixing region to the values of the meson energy and
the dynamical quark mass is explored and an assessment made of the
dectectibility of string breaking in a practical lattice simulation.Comment: 14 pages, LATEX2e, 2 figures, uses styles[12pt,a4,epsf
Mixing Scenarios for Lattice String Breaking
We present some simple scenarios for string breaking on the lattice based on
a crude strong coupling model introduced previously. We review the dependence
of the model on lattice spacing and extend it to include degenerate dynamical
quarks and also meson exchange diagrams. A comparison is made between quenched
and unquenched calculations. We examine string breaking in the presence of a
static quark-diquark system, a situation that is specific to SU(3).Comment: 15 pages 5 fig
Spherical Formulation for Diagramatic Evaluations on a Manifold with Boundary
The mathematical formalism necessary for the diagramatic evaluation of
quantum corrections to a conformally invariant field theory for a
self-interacting scalar field on a curved manifold with boundary is considered.
The evaluation of quantum corrections to the effective action past one-loop
necessitates diagramatic techniques. Diagramatic evaluations and higher
loop-order renormalisation can be best accomplished on a Riemannian manifold of
constant curvature accommodating a boundary of constant extrinsic curvature. In
such a context the stated evaluations can be accomplished through a consistent
interpretation of the Feynman rules within the spherical formulation of the
theory for which the method of images allows. To this effect, the mathematical
consequences of such an interpretation are analyzed and the spherical
formulation of the Feynman rules on the bounded manifold is, as a result,
developed.Comment: 12 pages, references added. To appear in Classical and Quantum
Gravit
The contribution of O(alpha) radiative corrections to the renormalised anisotropy and application to general tadpole improvement schemes: addendum to "One loop calculation of the renormalised anisotropy for improved anisotropic gluon actions on a lattice" [hep-lat/0208010]
General O(alpha) radiative corrections to lattice actions may be interpreted
as counterterms that give additive contributions to the one-loop
renormalisation of the anisotropy. The effect of changing the radiative
coefficients is thus easily calculable. In particular, the results obtained in
a previous paper for Landau mean link improved actions apply in any tadpole
improvement scheme. We explain how this method can be exploited when tuning
radiatively improved actions. Efficient methods for self-consistently tuning
tadpole improvement factors are also discussed.Comment: 3 pages of revte
Effective diffusion constant in a two dimensional medium of charged point scatterers
We obtain exact results for the effective diffusion constant of a two
dimensional Langevin tracer particle in the force field generated by charged
point scatterers with quenched positions. We show that if the point scatterers
have a screened Coulomb (Yukawa) potential and are uniformly and independently
distributed then the effective diffusion constant obeys the
Volgel-Fulcher-Tammann law where it vanishes. Exact results are also obtained
for pure Coulomb scatterers frozen in an equilibrium configuration of the same
temperature as that of the tracer.Comment: 9 pages IOP LaTex, no figure
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