8,309 research outputs found
Applied lattice gauge calculations: diquark content of the nucleon
As an example of an application of lattice QCD we describe a computation of
four-quark operators in the nucleon. The results are interpreted in a diquark
language.Comment: 6 pages, 1 figure, Invited talk given by M. G\"ockeler at the
European Workshop on the QCD Structure of the Nucleon (QCD - N'02), Ferrara,
Italy, 3-6 Apr 200
Duality in linearized gravity
We show that duality transformations of linearized gravity in four
dimensions, i.e., rotations of the linearized Riemann tensor and its dual into
each other, can be extended to the dynamical fields of the theory so as to be
symmetries of the action and not just symmetries of the equations of motion.
Our approach relies on the introduction of two "superpotentials", one for the
spatial components of the spin-2 field and the other for their canonically
conjugate momenta. These superpotentials are two-index, symmetric tensors. They
can be taken to be the basic dynamical fields and appear locally in the action.
They are simply rotated into each other under duality. In terms of the
superpotentials, the canonical generator of duality rotations is found to have
a Chern-Simons like structure, as in the Maxwell case.Comment: 10 pages; introduction rewritten and references adde
A Non-Hermitean Particle in a Disordered World
There has been much recent work on the spectrum of the random non-hermitean
Hamiltonian which models the physics of vortex line pinning in superconductors.
This note is loosely based on the talk I gave at the conference "New Directions
in Statistical Physics" held in Taipei, August 1997. We describe here new
results in spatial dimensions higher than one. We also give an expression for
the spectrum within the WKB approximation.Comment: latex file, 23 pages, 7 .ps figure
The topology of U-duality (sub-)groups
We discuss the topology of the symmetry groups appearing in compactified
(super-)gravity, and discuss two applications. First, we demonstrate that for 3
dimensional sigma models on a symmetric space G/H with G non-compact and H the
maximal compact subgroup of G, the possibility of oxidation to a higher
dimensional theory can immediately be deduced from the topology of H. Second,
by comparing the actual symmetry groups appearing in maximal supergravities
with the subgroups of SL(32,R) and Spin(32), we argue that these groups cannot
serve as a local symmetry group for M-theory in a formulation of de Wit-Nicolai
type.Comment: 18 pages, LaTeX, 1 figure, 2 table
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