49 research outputs found

### The Mass Spectrum of a Static Adjoint Particle

The bound states of fermions in the adjoint representation are of interest in
supersymmetric models. We investigate the energy spectrum of the simplest --
the gluino-gluon bound states -- on several lattices in the quenched
approximation. We use a static approximation for the gluino propagator. We find
continuum limits of the splitting between the few lowest states, with the
energy difference between the two lowest states of $354 \pm 9$ MeV.Comment: 3 pages, Latex, to appear Lattice 97 proceding

### Science and models of divine action

Some possible conceptualizations of divine action within the world are considered in the light of modern scientific insights. A selection of types of approach is investigated, including: (i) that which makes use of a strong theological determinism; (ii) that which formulates non- deterministic models of God's action to be in principle careless of the particular findings of modern science; (iii) that which sees science itself as the key to understanding how God might act; (iv) that of process theology which views God as immanently present within the physical processes themselves. In the evaluation of these models, a critical realism is adopted with regard to scientific findings. It is concluded that the type of approach (ii) independent of science is not likely to succeed. Also, models of type (iii) are unsatisfactory. Types (i) and (iv), theological determinism and process theology, in their different ways offer more promise, although each has its own characteristic problems and limitations. However, it is admitted that any finite theological system is likely to encounter problematic areas; it therefore remains possible that the most adequate such system overall might choose its difficulties to be in relation to science

### On the screening of the potential between adjoint sources in $QCD_3$

We calculate the potential between adjoint sources in $SU(2)$ pure gauge
theory in three dimensions. We investigate whether the potential saturates at
large separations due to the creation of a pair of gluelumps, colour-singlet
states formed when glue binds to an adjoint source.Comment: 3 pages, uuencoded Z-compressed postscript file, contribution to
Lattice '9

### Lattice sum rules for the colour fields

We analyse the sum rules describing the action and energy in the colour
fields around glueballs, torelons and static potentials.Comment: 9 pages LATEX, (typos corrected, to appear in Phys Rev D

### Non-perturbative determination of beta-functions and excited string states from lattices

We use lattice sum rules for the static quark potential to determine the
beta-function for symmetric and asymmetric lattices non-perturbatively. We also
study the colour field distributions in excited gluonic states.Comment: 9 pages, LATEX, 1 postscript figur

### Exploring Correlation Methods to Determine QCD beta-Functions on the Lattice

We investigate -- as an alternative to usual Monte Carlo Renormalization
Group methods -- the feasibility of extracting QCD beta-functions directly from
a lattice analysis of correlations between the action and Wilson loops. We test
this correlation technique numerically in four dimensional SU(2) gauge theory,
on a 16^4 lattice at beta = 2.5 and find very promising results.Comment: 12 pages, 2 Figure

### Glueball and gluelump spectrum in abelian projected QCD

We study glueball and gluelump spectra calculated after abelian projection in
both quenched and $N_f=2$ full QCD. The abelian projection is made after MA
gauge fixing. We demonstrate that both spectra can be recovered despite the
problem with positivity. We suggest the interpretation of some of the gluelump
states in the language of the abelian projected theory.Comment: Lattice 2001(confinement), 3 page

### Breaking of the adjoint string in 2+1 dimensions

The roughly linear rise of the potential found between adjoint sources in
SU(N) in lattice simulations is expected to saturate into a state of two
`gluelumps' due to gluonic screening. We examine this in SU(2) in 2+1
dimensions. Crossover between string-like and broken states is clearly seen by
the mixing-matrix technique, using different operators to probe the two states;
the breaking behaviour is rather abrupt. Furthermore, we are able to show that
both types of operator have a finite overlap with both states; in the case of
the Wilson loops the overlap with the broken string is, as predicted, very
small.Comment: LaTeX2e, 20 pages, 15 figures with epsfig; uses amstex, amssymb,
a4wide; minor change to presentation (notation for operators) onl

### Gluelump Spectrum in the Bag Model

We explore the ordering of the lowest levels in a simple bag model of the
``gluelump'' of Michael and also discuss, again within the context of the bag
model, the related problem of hybrid potentials in the limit of very small
spacing between quark and anti-quark sources.Comment: 10 page

### ``GLUELUMP'' SPECTRUM AND ADJOINT SOURCE POTENTIAL IN LATTICE QCD$_3$

We calculate the potential between ``quarks'' which are in the adjoint
representation of SU(2) color in the three-dimensional lattice theory. We work
in the scaling region of the theory and at large quark separations $R$. We also
calculate the masses $M_{Qg}$ of color-singlet bound states formed by coupling
an adjoint quark to adjoint glue (``gluelumps''). Good scaling behavior is
found for the masses of both magnetic (angular momentum $J=0$) and electric
($J=1$) gluelumps, and the magnetic gluelump is found to be the lowest-lying
state. It is naively expected that the potential for adjoint quarks should
saturate above a separation $R_{\rm scr}$ where it becomes energetically
favorable to produce a pair of gluelumps. We obtain a good estimate of the
naive screening distance $R_{\rm scr}$. However we find little evidence of
saturation in the potential out to separations $R$ of about twice $R_{\rm
scr}$.Comment: 8 pages plus 8 figures in 2 postscript files (uuencoded