1,312 research outputs found
Making Non-Associative Algebra Associative
Based on results about open string correlation functions, a nonassociative
algebra was proposed in a recent paper for D-branes in a background with
nonvanishing . We show that our associative algebra obtained by quantizing
the endpoints of an open string in an earlier work can also be used to
reproduce the same correlation functions. The novelty of this algebra is that
functions on the D-brane do not form a closed algebra. This poses a problem to
define gauge transformations on such noncommutative spaces. We propose a
resolution by generalizing the description of gauge transformations which
naturally involves global symmetries. This can be understood in the context of
matrix theory.Comment: 12 pages, Latex, acknowledgement adde
Nambu Bracket for M Theory
In this article we give a concise review of recent progress in our
understanding of the Lie 3-algebra and their application to the
Bagger-Lambert-Gustavsson model describing multiple M2-branes in M theory.Comment: 13 pages, prepared for The Fourth International Symposium on
Symmetries in Subatomic Physics (SSP 2009), minor modification, references
adde
Comment on Self-Consistent Model of Black Hole Formation and Evaporation
In an earlier work, Kawai et al proposed a model of black-hole formation and
evaporation, in which the geometry of a collapsing shell of null dust is
studied, including consistently the back reaction of its Hawking radiation. In
this note, we illuminate the implications of their work, focusing on the
resolution of the information loss paradox and the problem of the firewall.Comment: 16 pages, 6 figures, references adde
The Absence of Horizon in Black-Hole Formation
With the back-reaction of Hawking radiation taken into consideration, the
work of Kawai, Matsuo and Yokokura has shown that, under a few assumptions, the
collapse of matter does not lead to event horizon nor apparent horizon. In this
paper, we relax their assumptions and elaborate on the space-time geometry of a
generic collapsing body with spherical symmetry. The geometry outside the
collapsing sphere is found to be approximated by the geometry outside the
white-hole horizon, hence the collapsing matter remains outside the
Schwarzschild radius. As particles in Hawking radiation are created in the
vicinity of the collapsing matter, the information loss paradox is alleviated.
Assuming that the collapsing body evaporates within finite time, there is no
event horizon.Comment: 28 pages, minor modificatio
Noncommutative Spacetime, Stringy Spacetime Uncertainty Principle, and Density Fluctuations
We propose a variation of spacetime noncommutative field theory to realize
the stringy spacetime uncertainty relation without breaking any of the global
symmetries of the homogeneous isotropic universe. We study the spectrum of
metric perturbations in this model for a wide class of accelerating background
cosmologies. Spacetime noncommutativity leads to a coupling between the
fluctuation modes and the background cosmology which is nonlocal in time. For
each mode, there is a critical time at which the spacetime uncertainty relation
is saturated. This is the time when the mode is generated. These effects lead
to a spectrum of fluctuations whose spectral index is different from what is
obtained for commutative spacetime in the infrared region, but is unchanged in
the ultraviolet region. In the special case of an exponentially expanding
background, we find a scale-invariant spectrum. but with a different magnitude
than in the context of commutative spacetime if the Hubble constant is above
the string scale.Comment: 10 page
Aspects of Effective Theory for Multiple M5-Branes Compactified On Circle
A supersymmetric non-Abelian self-dual gauge theory with the explicit
introduction of Kaluza-Klein modes is proposed to give a classical description
of multiple M5-branes on . The gauge symmetry is parametrized
by Lie-algebra valued 1-forms with the redundancy of a 0-form, and the
supersymmetry transformations without gauge-fixing are given. We study BPS
configurations involving KK modes, including M-waves and M2-branes with
non-trivial distributions around the circle. Finally, this supersymmetric gauge
theory of two-forms can be equipped with more general non-Abelian gerbes in
five dimensions.Comment: 34 pages, minor modificatio
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