752 research outputs found
Supersymmetric and Kappa-invariant Coincident D0-Branes
We propose a generic supersymmetric and kappa-invariant action for describing
coincident D0-branes with non-abelian matter fields on their worldline. The
action is shown to be in agreement with the Matrix Theory limit of the
ND0-brane effective action.Comment: JHEP style, 1+8 page
Entropy of Non-Extreme Charged Rotating Black Holes in String Theory
We give the explicit expression for four-dimensional rotating charged black
hole solutions of N=4 (or N=8) superstring vacua, parameterized by the ADM
mass, four charges (two electric and two magnetic charges, each arising from a
different U(1) gauge factors), and the angular momentum (as well as the
asymptotic values of four toroidal moduli of two-torus and the dilaton-axion
field). The explicit form of the thermodynamic entropy is parameterized in a
suggestive way as a sum of the product of the `left-moving' and the
`right-moving' terms, which may have an interpretation in terms of the
microscopic degrees of freedom of the corresponding D-brane configuration. We
also give an analogous parameterization of the thermodynamic entropy for the
recently obtained five-dimensional rotating charged black holes parameterized
by the ADM mass, three U(1) charges and two rotational parameters (as well as
the asymptotic values of one toroidal modulus and the dilaton).Comment: 14 pages, uses RevTex, the revised version with minor corrections to
appear in Phys. Rev.
Adding a Brane to the Brane-Anti-Brane Action in BSFT
We attempt to generalize the effective action for the D-brane-anti-D-brane
system obtained from boundary superstring field theory (BSFT) by adding an
extra D-brane to it to obtain a covariantized action for 2 D-branes and 1
anti-D-brane. We discuss the approximations made to obtain the effective action
in closed form. Among other properties, this effective action admits solitonic
solutions of codimension 2 (vortices) when one of the D-brane is far separated
from the brane-anti-brane pair.Comment: 23 pages, 2 figures, minor revision
Fuzzy BIon
We construct a solution of the BFSS matrix theory, which is a counterpart of
the BIon solution representing a fundamental string ending on a bound state of
a D2-brane and D0-branes. We call this solution the `fuzzy BIon' and show that
this configuration preserves 1/4 supersymmetry of type IIA superstring theory.
We also construct an effective action for the fuzzy BIon by analyzing the
nonabelian Born-Infeld action for D0-branes. When we take the continuous limit,
with some conditions, this action coincides with the effective action for the
BIon configuration.Comment: 11 pages, 1 figure, reference and note adde
Counting Supertubes
The quantum states of the supertube are counted by directly quantizing the
linearized Born-Infeld action near the round tube. The result is an entropy , in accord with conjectures in the
literature. As a result, supertubes may be the generic D0-F1 bound state. Our
approach also shows directly that supertubes are marginal bound states with a
discrete spectrum. We also discuss the relation to recent suggestions of Mathur
et al involving three-charge black holes.Comment: 15 pages, v2: reference corrected; v3: few corrections and explicit
derivation of a relation are added to appendix
Avalanches and the Renormalization Group for Pinned Charge-Density Waves
The critical behavior of charge-density waves (CDWs) in the pinned phase is
studied for applied fields increasing toward the threshold field, using
recently developed renormalization group techniques and simulations of
automaton models. Despite the existence of many metastable states in the pinned
state of the CDW, the renormalization group treatment can be used successfully
to find the divergences in the polarization and the correlation length, and, to
first order in an expansion, the diverging time scale. The
automaton models studied are a charge-density wave model and a ``sandpile''
model with periodic boundary conditions; these models are found to have the
same critical behavior, associated with diverging avalanche sizes. The
numerical results for the polarization and the diverging length and time scales
in dimensions are in agreement with the analytical treatment. These
results clarify the connections between the behaviour above and below
threshold: the characteristic correlation lengths on both sides of the
transition diverge with different exponents. The scaling of the distribution of
avalanches on the approach to threshold is found to be different for automaton
and continuous-variable models.Comment: 29 pages, 11 postscript figures included, REVTEX v3.0 (dvi and PS
files also available by anonymous ftp from external.nj.nec.com in directory
/pub/alan/cdwfigs
Collective Dynamics of One-Dimensional Charge Density Waves
The effect of disorder on the static and dynamic behaviour of one-dimensional
charge density waves at low temperatures is studied by analytical and numerical
approaches. In the low temperature region the spatial behaviour of the
phase-phase correlation function is dominated by disorder but the roughness
exponent remains the same as in the pure case. Contrary to high dimensional
systems the dependence of the creep velocity on the electric field is described
by an analytic function.Comment: 4 pages, 4 figure
A New Cosmological Scenario in String Theory
We consider new cosmological solutions with a collapsing, an intermediate and
an expanding phase. The boundary between the expanding (collapsing) phase and
the intermediate phase is seen by comoving observers as a cosmological past
(future) horizon. The solutions are naturally embedded in string and M-theory.
In the particular case of a two-dimensional cosmology, space-time is flat with
an identification under boost and translation transformations. We consider the
corresponding string theory orbifold and calculate the modular invariant
one-loop partition function. In this case there is a strong parallel with the
BTZ black hole. The higher dimensional cosmologies have a time-like curvature
singularity in the intermediate region. In some cases the string coupling can
be made small throughout all of space-time but string corrections become
important at the singularity. This happens where string winding modes become
light which could resolve the singularity. The new proposed space-time casual
structure could have implications for cosmology, independently of string
theory.Comment: 28 pages, 3 figures; v2: Added new subsection relating
two-dimensional model to BTZ black hole, typos corrected and references
added; v3: minor corrections, PRD versio
Towards a supersymmetric non-abelian Born-Infeld theory
We define an iterative procedure to obtain a non-abelian generalization of
the Born-Infeld action. This construction is made possible by the use of the
severe restrictions imposed by kappa-symmetry. We have calculated all bosonic
terms in the action up to terms quartic in the Yang-Mills field strength and
all fermion bilinear terms up to terms cubic in the field strength. Already at
this order the fermionic terms do not satisfy the symmetric trace-prescription.Comment: 9 pp. Latex, to appear in the proceedings of the Strings 2000
conferenc
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