8 research outputs found
Coordinate-invariant Path Integral Methods in Conformal Field Theory
We present a coordinate-invariant approach, based on a Pauli-Villars measure,
to the definition of the path integral in two-dimensional conformal field
theory. We discuss some advantages of this approach compared to the operator
formalism and alternative path integral approaches. We show that our path
integral measure is invariant under conformal transformations and field
reparametrizations, in contrast to the measure used in the Fujikawa
calculation, and we show the agreement, despite different origins, of the
conformal anomaly in the two approaches. The natural energy-momentum in the
Pauli-Villars approach is a true coordinate-invariant tensor quantity, and we
discuss its nontrivial relationship to the corresponding non-tensor object
arising in the operator formalism, thus providing a novel explanation within a
path integral context for the anomalous Ward identities of the latter. We
provide a direct calculation of the nontrivial contact terms arising in
expectation values of certain energy-momentum products, and we use these to
perform a simple consistency check confirming the validity of the change of
variables formula for the path integral. Finally, we review the relationship
between the conformal anomaly and the energy-momentum two-point functions in
our formalism.Comment: Corrected minor typos. To appear in International Journal of Modern
Physics
Kaon Condensation in ``Nuclear Star" Matter
The critical density for kaon condensation in ``nuclear star" matter is
computed up to two-loop order {\it in medium} (corresponding to
next-to-next-to-leading order in chiral perturbation theory in free space) with
a heavy-baryon effective chiral Lagrangian whose parameters are determined from
scattering and kaonic atom data. To the order considered, the kaon
self-energy has highly non-linear density dependence in dense matter. We find
that the four-Fermi interaction terms in the chiral Lagrangian play an
important role in triggering condensation, predicting for ``natural" values of
the four-Fermi interactions a rather low critical density, .Comment: 12 pages and 2 figures(LaTeX), SNUTP-94-28. The fig. 3 is replaced,
with some changes in the text but the conclusion is not affected by these
change
Weyl-Conformally-Invariant Lightlike p-Brane Theories: New Aspects in Black Hole Physics and Kaluza-Klein Dynamics
We introduce and study in some detail the properties of a novel class of
Weyl-conformally invariant p-brane theories which describe intrinsically
lightlike branes for any odd world-volume dimension. Their dynamics
significantly differs from that of the ordinary (conformally non-invariant)
Nambu-Goto p-branes. We present explicit solutions of the Weyl-invariant
lightlike brane- (WILL-brane) equations of motion in various gravitational
models of physical relevance exhibiting various new phenomena. In D=4 the
WILL-membrane serves as a material and charged source for gravity and
electromagnetism in the coupled Einstein-Maxwell-WILL-membrane system; it
automatically positions itself on (``straddles'') the common event horizon of
the corresponding matching black hole solutions, thus providing an explicit
dynamical realization of the membrane paradigm in black hole physics. In
product spaces of interest in Kaluza-Klein theories the WILL-brane wraps
non-trivially around the compact (internal)dimensions and still describes
massless mode dynamics in the non-compact (space-time) dimensions. Due to
nontrivial variable size of the internal compact dimensions we find new types
of physically interesting solutions describing massless brane modes trapped on
bounded planar circular orbits with non-trivial angular momentum, and with
linear dependence between energy and angular momentum.Comment: 28 pages, published versio
Dielectric Fundamental Strings in Matrix String Theory
Matrix string theory is equivalent to type IIA superstring theory in the
light-cone gauge, together with extra degrees of freedom representing D-brane
states. It is therefore the appropriate framework in which to study systems of
multiple fundamental strings expanding into higher-dimensional D-branes.
Starting from Matrix theory in a weakly curved background, we construct the
linear couplings of closed string fields to type IIA Matrix strings. As a
check, we show that at weak coupling the resulting action reproduces light-cone
gauge string theory in a weakly curved background. Further dualities give a
type IIB Matrix string theory and a type IIA theory of Matrix strings with
winding. We comment on the dielectric effect in each of these theories, giving
some explicit solutions describing fundamental strings expanding into various
Dp-branes.Comment: Plain LaTeX, 25 pages. Reference added. Version to appear to NP