792 research outputs found
A Hidden Twelve-Dimensional SuperPoincare Symmetry In Eleven Dimensions
First, we review a result in our previous paper, of how a ten-dimensional
superparticle, taken off-shell, has a hidden eleven-dimensional superPoincare
symmetry. Then, we show that the physical sector is defined by three
first-class constraints which preserve the full eleven-dimensional symmetry.
Applying the same concepts to the eleven dimensional superparticle, taken
off-shell, we discover a hidden twelve dimensional superPoincare symmetry that
governs the theory.Comment: 13 page
Two-Time Physics with gravitational and gauge field backgrounds
It is shown that all possible gravitational, gauge and other interactions
experienced by particles in ordinary d-dimensions (one-time) can be described
in the language of two-time physics in a spacetime with d+2 dimensions. This is
obtained by generalizing the worldline formulation of two-time physics by
including background fields. A given two-time model, with a fixed set of
background fields, can be gauged fixed from d+2 dimensions to (d-1) +1
dimensions to produce diverse one-time dynamical models, all of which are
dually related to each other under the underlying gauge symmetry of the unified
two-time theory. To satisfy the gauge symmetry of the two-time theory the
background fields must obey certain coupled differential equations that are
generally covariant and gauge invariant in the target d+2 dimensional
spacetime. The gravitational background obeys a null homothety condition while
the gauge field obeys a differential equation that generalizes a similar
equation derived by Dirac in 1936. Explicit solutions to these coupled
equations show that the usual gravitational, gauge, and other interactions in d
dimensions may be viewed as embedded in the higher d+2 dimensional space, thus
displaying higher spacetime symmetries that otherwise remain hidden.Comment: Latex, 19 pages, references adde
Noncommutative Sp(2,R) Gauge Theories - A Field Theory Approach to Two-Time Physics
Phase-space and its relativistic extension is a natural space for realizing
Sp(2,R) symmetry through canonical transformations. On a Dx2 dimensional
covariant phase-space, we formulate noncommutative field theories, where
Sp(2,R) plays a role as either a global or a gauge symmetry group. In both
cases these field theories have potential applications, including certain
aspects of string theories, M-theory, as well as quantum field theories. If
interpreted as living in lower dimensions, these theories realize Poincare'
symmetry linearly in a way consistent with causality and unitarity. In case
Sp(2,R) is a gauge symmetry, we show that the spacetime signature is determined
dynamically as (D-2,2). The resulting noncommutative Sp(2,R) gauge theory is
proposed as a field theoretical formulation of two-time physics: classical
field dynamics contains all known results of `two-time physics', including the
reduction of physical spacetime from D to (D-2) dimensions, with the associated
`holography' and `duality' properties. In particular, we show that the solution
space of classical noncommutative field equations put all massless scalar,
gauge, gravitational, and higher-spin fields in (D-2) dimensions on
equal-footing, reminiscent of string excitations at zero and infinite tension
limits.Comment: 32 pages, LaTe
Superstar in Noncommutative Superspace via Covariant Quantization of the Superparticle
A covariant quantization method is developed for the off-shell superparticle
in 10 dimensions. On-shell it is consistent with lightcone quantization, while
off-shell it gives a noncommutative superspace that realizes non-linearly a
hidden 11-dimensional super Poincare symmetry. The non-linear commutation rules
are then used to construct the supersymmetric generalization of the covariant
Moyal star product in noncommutative superspace. As one of the possible
applications, we propose this new product as the star product in supersymmetric
string field theory. Furthermore, the formalism introduces new techniques and
concepts in noncommutative (super)geometry.Comment: 17 pages, LaTe
Conformally Exact Metric and Dilaton in String Theory on Curved Spacetime
Using a Hamiltonian approach to gauged WZW models, we present a general
method for computing the conformally exact metric and dilaton, to all orders in
the expansion, for any bosonic, heterotic, or type-II superstring model
based on a coset . We prove the following relations: (i) For type-II
superstrings the conformally exact metric and dilaton are identical to those of
the non-supersymmetric {\it semi-classical} bosonic model except for an overall
renormalization of the metric obtained by . (ii) The exact
expressions for the heterotic superstring are derived from their exact bosonic
string counterparts by shifting the central extension (but an
overall factor remains unshifted). (iii) The combination
is independent of and therefore can be computed in lowest
order perturbation theory as required by the correct formulation of a
conformally invariant path integral measure. The general formalism is applied
to the coset models that are relevant for
string theory on curved spacetime. Explicit expressions for the conformally
exact metric and dilaton for the cases are given. In the
semiclassical limit our results agree with those obtained with
the Lagrangian method up to 1-loop in perturbation theory.Comment: USC-92/HEP-B2, 19 pages and 3 figure
Hamiltonian Noether theorem for gauge systems and two time physics
The Noether theorem for Hamiltonian constrained systems is revisited. In
particular, our review presents a novel method to show that the gauge
transformations are generated by the conserved quantities associated with the
first class constraints. We apply our results to the relativistic point
particle, to the Friedberg et al. model and, with special emphasis, to two time
physics.Comment: 20 pages, Latex, references added, the "massless" sense of (87) is
clarifie
Universal aspects of string propagation on curved backgrounds
String propagation on D-dimensional curved backgrounds with Lorentzian
signature is formulated as a geometrical problem of embedding surfaces. When
the spatial part of the background corresponds to a general WZW model for a
compact group, the classical dynamics of the physical degrees of freedom is
governed by the coset conformal field theory SO(D-1)/SO(D-2), which is
universal irrespective of the particular WZW model. The same holds for string
propagation on D-dimensional flat space. The integration of the corresponding
Gauss-Codazzi equations requires the introduction of (non-Abelian) parafermions
in differential geometry.Comment: 15 pages, latex. Typo in Eq. (2.12) is corrected. Version to be
published in Phys. Rev.
U*(1,1) Noncommutative Gauge Theory As The Foundation of 2T-Physics in Field Theory
A very simple field theory in noncommutative phase space X^{M},P^{M} in d+2
dimensions, with a gauge symmetry based on noncommutative u*(1,1), furnishes
the foundation for the field theoretic formulation of Two-Time Physics. This
leads to a remarkable unification of several gauge principles in d dimensions,
including Maxwell, Einstein and high spin gauge principles, packaged together
into one of the simplest fundamental gauge symmetries in noncommutative quantum
phase space in d+2 dimensions. A gauge invariant action is constructed and its
nonlinear equations of motion are analyzed. Besides elegantly reproducing the
first quantized worldline theory with all background fields, the field theory
prescribes unique interactions among the gauge fields. A matrix version of the
theory, with a large N limit, is also outlinedComment: 24 pages, LaTe
Solving Witten's string field theory using the butterfly state
We solve the equation of motion of Witten's cubic open string field theory in
a series expansion using the regulated butterfly state. The expansion parameter
is given by the regularization parameter of the butterfly state, which can be
taken to be arbitrarily small. Unlike the case of level truncation, the
equation of motion can be solved for an arbitrary component of the Fock space
up to a positive power of the expansion parameter. The energy density of the
solution is well-defined and remains finite even in the singular butterfly
limit, and it gives approximately 68% of the D25-brane tension for the solution
at the leading order. Moreover, it simultaneously solves the equation of motion
of vacuum string field theory, providing support for the conjecture at this
order. We further improve our ansatz by taking into account next-to-leading
terms, and find two numerical solutions which give approximately 88% and 109%,
respectively, of the D25-brane tension for the energy density. These values are
interestingly close to those by level truncation at level 2 without gauge
fixing studied by Rastelli and Zwiebach and by Ellwood and Taylor.Comment: 38 pages, no figures, LaTeX2e; v2: the footnote on hep-th/0302151
changed and moved to the introduction; v3: minor typos corrected, published
versio
- …