924 research outputs found
WZW-like Action for Heterotic String Field Theory
We complete the construction of the Neveu-Schwarz sector of heterotic string
field theory begun in hep-th/0406212 by giving a closed-form expression for the
action and gauge transformations. Just as the Wess-Zumino-Witten (WZW) action
for open superstring field theory can be constructed from pure-gauge fields in
bosonic open string field theory, our heterotic string field theory action is
constructed from pure-gauge fields in bosonic closed string field theory. The
construction involves a simple alternative form of the WZW action which is
consistent with the algebraic structures of closed string field theory.Comment: 22 pages, no figures, LaTeX2
Ultra-violet Behavior of Bosonic Quantum Membranes
We treat the action for a bosonic membrane as a sigma model, and then compute
quantum corrections by integrating out higher membrane modes. As in string
theory, where the equations of motion of Einstein's theory emerges by setting
, we find that, with certain assumptions, we can recover the
equations of motion for the background fields. Although the membrane theory is
non-renormalizable on the world volume by power counting, the investigation of
the ultra-violet behavior of membranes may give us insight into the
supersymmetric case, where we hope to obtain higher order M-theory corrections
to 11 dimensional supergravity.Comment: 25 pages, Latex, no figure
N-String Vertices in String Field Theory
We give the general form of the vertex corresponding to the interaction of an
arbitrary number of strings. The technique employed relies on the ``comma"
representation of String Field Theory where string fields and interactions are
represented as matrices and operations between them such as multiplication and
trace. The general formulation presented here shows that the interaction vertex
of N strings, for any arbitrary N, is given as a function of particular
combinations of matrices corresponding to the change of representation between
the full string and the half string degrees of freedom.Comment: 22 pages, A4-Latex (latex twice), FTUV IFI
Hypoplastic Left Heart Syndrome with in Utero Closed Foramen Ovale: Case Report
Apresenta-se o caso clĂnico de um recĂ©m-
-nascido (RN) do sexo masculino, com
diagnĂłstico prĂ©-natal de sĂndrome do coração
esquerdo hipoplásico (SCEH), referenciado à s
37 semanas de gestação.
No ecocardiograma fetal apresentava SCEH
clássico com atrésia da aorta, válvula mitral
permeável e septo interauricular espessado,
mas com foramen ovale (FO) aparentemente
permeável. Parto eutócico de termo, PN =
2540g, necessidade de intubação
endotraqueal com ventilação assistida e
prostaglandina E1 intravenosa.
Imediatamente apĂłs o parto verificou-se
agravamento clĂnico com deterioração dos
valores gasimétricos. O ecocardiograma
confirmou o diagnĂłstico, levantando a
suspeita de encerramento do FO, que se
confirmou no exame hemodinâmico, feito de
seguida. Tentativa de atrioseptostomia de
Rashkind, sem sucesso. O RN faleceu, tendo
a autĂłpsia revelado SCEH com FO encerrado,
seio coronário aumentado e extensas
linfangiectasias pulmonares. O aumento do
seio coronário levou, neste caso, ao
diagnóstico pré-natal errado de FO permeável
com shunt esquerdo-direito
Light-cone Gauge NSR Strings in Noncritical Dimensions II -- Ramond Sector
Light-cone gauge superstring theory in noncritical dimensions corresponds to
a worldsheet theory with nonstandard longitudinal part in the conformal gauge.
The longitudinal part of the worldsheet theory is a superconformal field theory
called X^{\pm} CFT. We show that the X^{\pm} CFT combined with the
super-reparametrization ghost system can be described by free variables. It is
possible to express the correlation functions in terms of these free variables.
Bosonizing the free variables, we construct the spin fields and BRST invariant
vertex operators for the Ramond sector in the conformal gauge formulation. By
using these vertex operators, we can rewrite the tree amplitudes of the
noncritical light-cone gauge string field theory, with external lines in the
(R,R) sector as well as those in the (NS,NS) sector, in a BRST invariant way.Comment: 33 pages; v2: minor modification
Gravitational coupling to two-particle bound states and momentum conservation in deep inelastic scattering
The momentum conservation sum rule for deep inelastic scattering (DIS) from
composite particles is investigated using the general theory of relativity. For
two 1+1 dimensional examples, it shown that covariant theories automatically
satisy the DIS momentum conservation sum rule provided the bound state is
covariantilly normalized. Therefore, in these cases the two DIS sum rules for
baryon conservation and momentum conservation are equivalent
Spacetime Fermions in Light-cone Gauge Superstring Field Theory and Dimensional Regularization
We consider the dimensional regularization of the light-cone gauge type II
superstring field theories in the NSR formalism. In the previous work, we have
calculated the tree-level amplitudes with external lines in the (NS,NS) sector
using the regularization and shown that the desired results are obtained
without introducing contact term interactions. In this work, we study the
tree-level amplitudes with external lines in the Ramond sector. In order to
deal with them, we propose a worldsheet theory to be used instead of that for
the naive dimensional regularization. With the worldsheet theory, we regularize
and define the tree-level amplitudes by analytic continuation. We show that the
results coincide with those of the first quantized formulation.Comment: 28 pages, 5 figures; v2: more details of our manipulations in
subsection 3.2 added, figures and references added; v3: clarifications adde
Proposal of a topological M(atrix) theory
Keeping in mind the several models of M(atrix) theory we attempt to
understand the possible structure of the topological M(atrix) theory
``underlying'' these approaches. In particular we are motivated by the issue
about the nature of the structure of the vacuum of the topological M(atrix)
theory and how this could be related to the vacuum of the electroweak theory.
In doing so we are led to a simple topological matrix model. Moreover it is
intuitively expected from the current understanding that the noncommutative
nature of ``spacetime'' and background independence should lead to a
topological Model. The main purpose of this note is to propose a simple
topological Matrix Model which bears relation to F and M theories. Suggestions
on the origin of the chemical potential term appearing in the matrix models are
given.Comment: 14 pages revte
Thermal history of the string universe
Thermal history of the string universe based on the Brandenberger and Vafa's
scenario is examined. The analysis thereby provides a theoretical foundation of
the string universe scenario. Especially the picture of the initial oscillating
phase is shown to be natural from the thermodynamical point of view. A new tool
is employed to evaluate the multi state density of the string gas. This
analysis points out that the well-known functional form of the multi state
density is not applicable for the important region , and derives a
correct form of it.Comment: 39 pages, no figures, use revtex.sty, aps.sty, aps10.sty &
preprint.st
On a possible new R^2 theory of supergravity
We consider a new MacDowell-Mansouri R^2-type of supergravity theory, an
extension of conformal supergravity, based on the superalgebra Osp(1|8).
Invariance under local symmetries with negative Weyl weight is achieved by
imposing chirality-duality and double-duality constraints on curvatures, along
with the usual constraint of vanishing supertorsion. An analysis of the
remaining gauge symmetries shows that those with vanishing Weyl weight are
invariances of the action at the linearized level. For the symmetries with
positive Weyl weight we find that invariance of the action would require
further modifications of the transformation rules. This conclusion is supported
by a kinematical analysis of the closure of the gauge algebra.Comment: 52 pages, Late
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