2,499 research outputs found

### Axion-Dilaton Black Holes

In this talk some essential features of stringy black holes are described. We
consider charged four-dimensional axion-dilaton black holes. The Hawking
temperature and the entropy of all solutions are shown to be simple functions
of the squares of supercharges, defining the positivity bounds. Spherically
symmetric and multi black hole solutions are presented. The extreme solutions
have some unbroken supersymmetries. Axion-dilaton black holes with zero entropy
and zero area of the horizon form a family of stable particle-like objects,
which we call holons. We discuss the possibility of splitting of nearly extreme
black holes into holons.Comment: 8 pages, LATEX, (Talk presented at the TEXAS/PASCOS conference,
Berkeley, December 1992

### Inflation, Symmetry, and B-Modes

We examine the role of using symmetry and effective field theory in
inflationary model building. We describe the standard formulation of starting
with an approximate shift symmetry for a scalar field, and then introducing
corrections systematically in order to maintain control over the inflationary
potential. We find that this leads to models in good agreement with recent
data. On the other hand, there are attempts in the literature to deviate from
this paradigm by invoking other symmetries and corrections. In particular: in a
suite of recent papers, several authors have made the claim that standard
Einstein gravity with a cosmological constant and a massless scalar carries
conformal symmetry. They further claim that such a theory carries another
hidden symmetry; a global SO(1,1) symmetry. By deforming around the global
SO(1,1) symmetry, they are able to produce a range of inflationary models with
asymptotically flat potentials, whose flatness is claimed to be protected by
these symmetries. These models tend to give rise to B-modes with small
amplitude. Here we explain that these authors are merely introducing a
redundancy into the description, not an actual conformal symmetry. Furthermore,
we explain that the only real (global) symmetry in these models is not at all
hidden, but is completely manifest when expressed in the Einstein frame; it is
in fact the shift symmetry of a scalar field. When analyzed systematically as
an effective field theory, deformations do not generally produce asymptotically
flat potentials and small B-modes, but other types of potentials with B-modes
of appreciable amplitude. Such simple models typically also produce the
observed red spectral index, Gaussian fluctuations, etc. In short: simple
models of inflation, organized by expanding around a shift symmetry, are in
excellent agreement with recent data.Comment: 9 pages in double column format. V2: Updated to coincide with version
published in Physics Letters

### Brane-anti-brane Democracy

We suggest a duality invariant formula for the entropy and temperature of
non-extreme black holes in supersymmetric string theory. The entropy is given
in terms of the duality invariant parameter of the deviation from extremality
and 56 SU(8) covariant central charges. It interpolates between the entropies
of Schwarzschild solution and extremal solutions with various amount of
unbroken supersymmetries and therefore serves for classification of black holes
in supersymmetric string theories. We introduce the second auxiliary 56 via
E(7) symmetric constraint. The symmetric and antisymmetric combinations of
these two multiplets are related via moduli to the corresponding two
fundamental representations of E(7): brane and anti-brane "numbers." Using the
CPT as well as C symmetry of the entropy formula and duality one can explain
the mysterious simplicity of the non-extreme black hole area formula in terms
of branes and anti-branes.Comment: LaTeX, 12 pages, no figure

### Multivalued Entropy of Supersymmetric Black Holes

The supersymmetric flow equations describing the flow of moduli from infinity
to the black hole horizon, and vice versa, are derived in the five-dimensional
theories where the moduli space of the very special geometry has disjoint
branches. The multiple solutions are derived from the `off the horizon'
attractor equation. Within each branch, the black hole entropy, as usual,
depends only on the near horizon attractor values of moduli, i.e. the entropy
depends on the charges and on coefficients of the cubic polynomial. It does not
depend on the values of the moduli fields at infinity. However, the entropy, as
well as the near horizon values of the moduli fields, are shown to depend on
the choice of the branch specified by the choice of the set of moduli at
infinity. We present examples of BPS black hole solutions with the same Q_I and
C_{IJK}, whose entropies differ significantly.Comment: 12 pages, 2 figures, Latex, JHEP styl

### Quantization of p-branes, D-p-branes and M-branes

Killing spinors of space-time BPS configurations play an important role in
quantization of theories with the fermionic worldvolume local symmetry. We show
here how it works for the GS superstring, BST supermembrane and M-5-brane. We
show that the non-linear generalization of the (2,0) d=6 tensor supermultiplet
action is the M-5-brane action in a Killing gauge. For D-p-branes the novel
feature of quantization is that they can be quantized Lorentz covariantly, in
particular, for D-0-brane a gauge exists where the action is covariant and
free. We present a general condition on possible choice of gauges for the
kappa-symmetric branes.Comment: 9 pages, Talk at STRINGS'97 Meeting, Amsterdam, The Netherlands,
16-21 Jun 199

- âŠ