94,619 research outputs found

### S^1-wrapped D3-branes on Conifolds

We construct a D3-brane wrapped on S^1, which is fibred over the resolved
conifold as its transverse space. Whereas a fractional D3-brane on the resolved
conifold is not supersymmetric and has a naked singularity, our solution is
supersymmetric and regular everywhere. We also consider an $S^1$-wrapped
D3-brane on the resolved cone over T^{1,1}/Z_2, as well as on the deformed
conifold. In the former case, we obtain a regular supergravity dual to a
certain four-dimensional field theory whose Lorentz and conformal symmetries
are broken in the IR region and restored in the UV limit.Comment: Latex, 14 pages, minor correction

### Smooth Cosmologies from M-theory

We review two ways in which smooth cosmological evolution between two de
Sitter phases can be obtained from M/string-theory. Firstly, we perform a
hyperbolic reduction of massive IIA* theory to D=6 N=(1,1) SU(2)xU(1) gauged de
Sitter supergravity, which supports smooth cosmological evolution between dS_4
x S^2 and a dS_6-type geometry. Secondly, we obtain four-dimensional de Sitter
gravity with SU(2) Yang-Mills gauge fields from a hyperbolic reduction of
standard eleven-dimensional supergravity. The four-dimensional theory supports
smooth cosmological evolution between dS_2 x S^2 and a dS_4-type geometry.
Although time-dependent, these solutions arise from a first-order system via a
superpotential construction. For appropriate choices of charges, these
solutions describe an expanding universe whose expansion rate is significantly
larger in the past than in the future, as required for an inflationary model.Comment: Latex, 7 pages, Contribution to Quantum Theory and Symmetries

### Non-singular Twisted S-branes From Rotating Branes

We show that rotating p-brane solutions admit an analytical continuation to
become twisted Sp-branes. Although a rotating p-brane has a naked singularity
for large angular momenta, the corresponding S-brane configuration is regular
everywhere and exhibits a smooth bounce between two phases of Minkowski
spacetime. If the foliating hyperbolic space of the transverse space is of even
dimension, such as for the twisted SM5-brane, then for an appropriate choice of
parameters the solution smoothly flows from a warped product of two-dimensional
de Sitter spacetime, five-dimensional Euclidean space and a hyperbolic 4-space
in the infinite past to Minkowski spacetime in the infinite future. We also
show that non-singular S-Kerr solutions can arise from higher-dimensional Kerr
black holes, so long as all (all but one) angular momenta are non-vanishing for
even (odd) dimensions.Comment: Latex, 20 page

### Gaussian Effective Potential and the Coleman's normal-ordering Prescription : the Functional Integral Formalism

For a class of system, the potential of whose Bosonic Hamiltonian has a
Fourier representation in the sense of tempered distributions, we calculate the
Gaussian effective potential within the framework of functional integral
formalism. We show that the Coleman's normal-ordering prescription can be
formally generalized to the functional integral formalism.Comment: 6 pages, revtex; With derivation details and an example added. To
appear in J. Phys.

### Absorption by Extremal D3-branes

The absorption in the extremal D3-brane background is studied for a class of
massless fields whose linear perturbations leave the ten-dimensional background
metric unperturbed, as well as the minimally-coupled massive scalar. We find
that various fields have the same absorption probability as that of the
dilaton-axion system, which is given exactly via the Mathieu equation. We
analyze the features of the absorption cross-sections in terms of effective
Schr\"odinger potentials, conjecture a general form of the dual effective
potentials, and provide explicit numerical results for the whole energy range.
As expected, all partial-wave absorption probabilities tend to zero (one) at
low (large) energies, and exhibit an oscillatory pattern as a function of
energy. The equivalence of absorption probabilities for various modes has
implications for the correlation functions on the field, including subleading
contributions on the field-theory side. In particular, certain half-integer and
integer spin fields have identical absorption probabilities, thus providing
evidence that the corresponding operator pairs on the field theory side belong
to the same supermultiplets.Comment: Latex, 9 figures and 17 page

### Bosonic Super Liouville System: Lax Pair and Solution

We study the bosonic super Liouville system which is a statistical
transmutation of super Liouville system. Lax pair for the bosonic super
Liouville system is constructed using prolongation method, ensuring the Lax
integrability, and the solution to the equations of motion is also considered
via Leznov-Saveliev analysis.Comment: LaTeX, no figures, 11 page

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