69 research outputs found
Self-Duality and Maximally Helicity Violating QCD Amplitudes
I review some recent work that describes the close analogy between self-dual
Yang--Mills amplitudes and QCD amplitudes with external gluons of positive
helicity. This analogy is carried at tree level for amplitudes with two
external quarks and up to one-loop for amplitudes involving only external
gluons.Comment: 10 pages, LaTeX, no figures. Proceedings of the "Low Dimensional
Field Theory Workshop, Telluride." Some ideas proposed by Duff and Isham have
been include
Poincar\'e Gauge Theory for Gravitational Forces in (1+1) Dimensions
We discuss in detail how string-inspired lineal gravity can be formulated as
a gauge theory based on the centrally extended Poincar\'e group in
dimensions. Matter couplings are constructed in a gauge invariant fashion, both
for point particles and Fermi fields. A covariant tensor notation is developed
in which gauge invariance of the formalism is manifest.Comment: 43 p., CTP#216
Temperature Expansions for Magnetic Systems
We derive finite temperature expansions for relativistic fermion systems in
the presence of background magnetic fields, and with nonzero chemical
potential. We use the imaginary-time formalism for the finite temperature
effects, the proper-time method for the background field effects, and zeta
function regularization for developing the expansions. We emphasize the
essential difference between even and odd dimensions, focusing on and
dimensions. We concentrate on the high temperature limit, but we also
discuss the limit with nonzero chemical potential.Comment: 25 pages, RevTe
Extended de Sitter Theory of Two Dimensional Gravitational Forces
We present a simple unifying gauge theoretical formulation of gravitational
theories in two dimensional spacetime. This formulation includes the effects of
a novel matter-gravity coupling which leads to an extended de Sitter symmetry
algebra on which the gauge theory is based. Contractions of this theory
encompass previously studied cases.Comment: 19pp, no figs., CTP 2228, UCONN-93-
Spatial Geometry of the Electric Field Representation of Non-Abelian Gauge Theories
A unitary transformation \Ps [E]=\exp (i\O [E]/g) F[E] is used to simplify
the Gauss law constraint of non-abelian gauge theories in the electric field
representation. This leads to an unexpected geometrization because
\o^a_i\equiv -\d\O [E]/\d E^{ai} transforms as a (composite) connection. The
geometric information in \o^a_i is transferred to a gauge invariant spatial
connection \G^i_{jk} and torsion by a suitable choice of basis vectors for
the adjoint representation which are constructed from the electric field
. A metric is also constructed from . For gauge group ,
the spatial geometry is the standard Riemannian geometry of a 3-manifold, and
for it is a metric preserving geometry with both conventional and
unconventional torsion. The transformed Hamiltonian is local. For a broad class
of physical states, it can be expressed entirely in terms of spatial geometric,
gauge invariant variables.Comment: 16pp., REVTeX, CERN-TH.7238/94 (Some revision on Secs.3 and 5; one
reference added
Boundary states for moving D-branes
We determine the boundary state for both the NS-NS and R-R sectors of
superstring theory. We show how they are modified under a boost. The boosted
boundary state is then used for computing the interaction of two D-branes
moving with constant velocity reproducing with a completely different method a
recent calculation by Bachas.Comment: 10 pages, LaTeX, no figures; Eqs. (47) and (48) correcte
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