71,719 research outputs found
Constructing cell data for diagram algebras
We show how the treatment of cellularity in families of algebras arising from
diagram calculi, such as Jones' Temperley--Lieb wreaths, variants on Brauer's
centralizer algebras, and the contour algebras of Cox et al (of which many
algebras are special cases), may be unified using the theory of tabular
algebras. This improves an earlier result of the first author (whose hypotheses
covered only the Brauer algebra from among these families).Comment: Approximately 38 pages, AMSTeX. Revised in light of referee comments.
To appear in the Journal of Pure and Applied Algebr
A model for multi-quark systems
As a step towards understanding multi-quark systems abundant in nature we
construct a model that reproduces the binding energies of static four-quark
systems. These energies have been calculated using SU(2) lattice gauge theory
for a set of six different geometries representative of the general case. The
model is based on ground and excited state two-body potentials and multi-quark
interaction terms.Comment: 10 pages, one LaTeX figur
An interquark potential model for multi-quark systems
A potential model for four interacting quarks is constructed in SU(2) from
six basis states -- the three partitions into quark pairs, where the gluon
field is either in its ground state or first excited state. With four
independent parameters to describe the interactions connecting these basis
states, it is possible to fit 100 pieces of data -- the ground and first
excited states of configurations from six different four-quark geometries
calculated on a 16^3*32 lattice.Comment: 14 page
Mesoscopic Noise Theory: Microscopics, or Phenomenology?
We argue, physically and formally, that existing diffusive models of noise
yield inaccurate microscopic descriptions of nonequilibrium current
fluctuations. The theoretical shortfall becomes pronounced in quantum-confined
metallic systems, such as the two-dimensional electron gas. In such systems we
propose a simple experimental test of mesoscopic validity for diffusive
theory's central claim: the smooth crossover between Johnson-Nyquist and shot
noise.Comment: Invited paper, UPoN'99 Conference, Adelaide. 13 pp, no figs. Minor
revisions to text and reference
A Classical Manifestation of the Pauli Exclusion Principle
The occupied and unoccupied fermionic BPS quantum states of a type-IIA string
stretched between a D6-brane and an orthogonal D2-brane are described in
M-theory by two particular holomorphic curves embedded in a Kaluza-Klein
monopole. The absence of multiply-occupied fermionic states --- the Pauli
exclusion principle --- is manifested in M-theory by the absence of any other
holomorphic curves satisfying the necessary boundary conditions. Stable,
non-BPS states with multiple strings joining the D6-brane and D2-brane are
described M-theoretically by non-holomorphic curves.Comment: harvmac 6 pages. Final version as published in JHE
Curvature terms in D-brane actions and their M-theory origin
We derive the complete terms of effective D-brane actions,
for arbitrary ambient geometries and world-volume embeddings, at lowest order
(disk-level) in the string-loop expansion. These terms reproduce the
corrections to string scattering amplitudes, and are consistent
with duality conjectures. In the particular case of the D3-brane with trivial
normal bundle, considerations of invariance lead to a
complete sum of D-instanton corrections for both the parity-conserving and the
parity-violating parts of the effective action. These corrections are required
for the cancellation of the modular anomalies of massless modes, and are
consistent with the absence of chiral anomalies in the intersection domain of
pairs of D-branes. We also show that the parity-conserving part of the
non-perturbative R^2 action follows from a one-loop quantum calculation in the
six-dimensional world-volume of the M5-brane compactified on a two-torus.Comment: tex file, 31 pages, uses harvmac. Some rewriting of section 2,
conclusions and appendix B, in particular in what concerns the discussion of
seven-branes in the conclusions and the structure of terms in
appendix B. Other minor corrections plus added reference
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