1,960 research outputs found
On Sasaki-Einstein manifolds in dimension five
We prove the existence of Sasaki-Einstein metrics on certain simply connected
5-manifolds where until now existence was unknown. All of these manifolds have
non-trivial torsion classes. On several of these we show that there are a
countable infinity of deformation classes of Sasaki-Einstein structures.Comment: 18 pages, Exposition was expanded and a reference adde
Inflation on Fractional Branes: D--Brane Inflation as D--Term Inflation
We describe a D--brane inflation model which consists of two fractional D3
branes separated on a transverse . Inflation arises due to the
resolved orbifold singularity of which corresponds to an anomalous D--term
on the brane. We show that D--brane inflation in the bulk corresponds to
D--term inflation on the brane. The inflaton and the trigger field parametrize
the interbrane distances on an respectively. After inflation the
branes reach a supersymmetric configuration in which they are at the origin of
but separated along the directions.Comment: 15 pages in phyzzx.tex; minor corrections including all factors of
2\pi; v3: more minor correction
The Volume of some Non-spherical Horizons and the AdS/CFT Correspondence
We calculate the volumes of a large class of Einstein manifolds, namely
Sasaki-Einstein manifolds which are the bases of Ricci-flat affine cones
described by polynomial embedding relations in C^n. These volumes are important
because they allow us to extend and test the AdS/CFT correspondence. We use
these volumes to extend the central charge calculation of Gubser (1998) to the
generalized conifolds of Gubser, Shatashvili, and Nekrasov (1999). These
volumes also allow one to quantize precisely the D-brane flux of the AdS
supergravity solution. We end by demonstrating a relationship between the
volumes of these Einstein spaces and the number of holomorphic polynomials
(which correspond to chiral primary operators in the field theory dual) on the
corresponding affine cone.Comment: 25 pp, LaTeX, 1 figure, v2: refs adde
Campus Vol VI N 4
Pierson, Pete. Untitled. Cartoon. 2.
Hawk, Pete. The First Big Snow . Prose. 3.
Smith, Orlo. A Day In the Life of Miss Campus . Picture. 5.
Pierson, Pete. Old Seniors never Die... Cartoon. 8.
Cole, Sam H. King . Just a Hobo . Prose. 10.
Johnson, C. P. Some Sons Of Denison . Prose. 12.
Anonymous. Last Will and Testament of the Senior Class . Prose. 14.
Kat, Kitty. Untitled. Prose. 16.
Spartan. Untitled. Prose. 16.
Shaft. Untitled. Prose. 16.
Pointer. Untitled. Prose. 16.
Tarnation. Untitled. Prose. 17.
Sundial. Untitled. Prose. 17.
Pup. Untitled. Prose. 17.
Aggrevator. Untitled. Prose. 17.
Gander, Green. Untitled. Prose. 17.
Mis-A-Sip. Untitled. Prose. 17.
Lyke. Untitled. Prose. 17
Cosmic D--term Strings as Wrapped D3 Branes
We describe cosmic D--term strings as D3 branes wrapped on a resolved
conifold. The matter content that gives rise to D--term strings is shown to
describe the world--volume theory of a space--filling D3 brane transverse to
the conifold which itself is a wrapped D5 brane. We show that, in this brane
theory, the tension of the wrapped D3 brane mathces that of the D--term string.
We argue that there is a new type of cosmic string which arises from fractional
D1 branes on the world--volume of a fractional D3 brane.Comment: 13 pages in phyzzx.tex; eq. (17) corrected, other minor corrections;
v3: more minor correction
D-brane dynamics near compactified NS5-branes
We examine the dynamics of a -brane in the background of coincident,
parallel 5-branes which have had one of their common transverse directions
compactified. We find that for small energy, bound orbits can exist at
sufficiently large distances where there will be no stringy effects. The orbits
are dependent upon the energy density, angular momentum and electric field. The
analysis breaks down at radial distances comparable with the compactification
radius and we must resort to using a modified form of the harmonic function in
this region.Comment: Latex, 20 pages, 6 figs, references adde
Tuning out vibrational levels in molecular electron energy-loss spectra
The phenomenon whereby features associated with certain vibrational levels in molecular states of mixed electronic character disappear under specific scattering conditions in electron energy-loss spectra is investigated. In particular, using a combination of experimental measurements and coupled-channel calculations, anomalous vibrational intensities in the mixed valence-Rydberg 1Π u←X1Σg+ transition of N 2 are explained. A single parameter, i.e., the ratio of the generalized electronic transition moments to the diabatic valence and Rydberg components of the mixed states, dependent on the experimental scattering conditions, is found to be essentially capable of describing all observed relative vibrational intensities, including the near disappearance of the b1Π u(v=5) feature for momentum-transfer-squared values K2 ≈ 0.3 a.u. This result highlights the interesting possibility of experimental control of molecular quantum-interference effects in electron energy-loss spectra, something that is not possible in optical spectra
A new wrinkle on the enhancon
We generalize the basic enhancon solution of Johnson, Peet and Polchinski by
constructing solutions without spherical symmetry. A careful consideration of
boundary conditions at the enhancon surface indicates that the interior of the
supergravity solution is still flat space in the general case. We provide some
explicit analytic solutions where the enhancon locus is a prolate or oblate
sphere.Comment: 19 pages, no figure
The Enhancon, Black Holes, and the Second Law
We revisit the physics of five-dimensional black holes constructed from D5-
and D1-branes and momentum modes in type IIB string theory compactified on K3.
Since these black holes incorporate D5-branes wrapped on K3, an enhancon locus
appears in the spacetime geometry. With a `small' number of D1-branes, the
entropy of a black hole is maximised by including precisely half as many
D5-branes as there are D1-branes in the black hole. Any attempts to introduce
more D5-branes, and so reduce the entropy, are thwarted by the appearance of
the enhancon locus above the horizon, which then prevents their approach. The
enhancon mechanism thereby acts to uphold the Second Law of Thermodynamics.
This result generalises: For each type of bound state object which can be made
of both types of brane, we show that a new type of enhancon exists at
successively smaller radii in the geometry, again acting to prevent any
reduction of the entropy just when needed. We briefly explore the appearance of
the enhancon in the black hole interior.Comment: 22 pages, 2 figures, latex, epsfig (v2: Fixed trivial typos.
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