184 research outputs found
Degeneration of ALF D_n Metrics
Beginning with the Legendre transform construction of hyperk\"ahler metrics,
we analyze the ALF version of the D_n metrics. We determine the constraint
equation obtained from extremizing the coordinate of the generating
function F(z,\bar{z},u,\bar{u},w) and study its behavior as we send two of the
mass parameters of the metric to zero. We find that the constraint
equation enforces the limit that the metric becomes that of multi-Taub-NUT.Comment: 14 pages, 7 figures, LaTeX, minor corrections, to appear in JHE
Linearizing Generalized Kahler Geometry
The geometry of the target space of an N=(2,2) supersymmetry sigma-model
carries a generalized Kahler structure. There always exists a real function,
the generalized Kahler potential K, that encodes all the relevant local
differential geometry data: the metric, the B-field, etc. Generically this data
is given by nonlinear functions of the second derivatives of K. We show that,
at least locally, the nonlinearity on any generalized Kahler manifold can be
explained as arising from a quotient of a space without this nonlinearity.Comment: 31 pages, some geometrical aspects clarified, typos correcte
Ricci-flat supertwistor spaces
We show that supertwistor spaces constructed as a Kahler quotient of a
hyperkahler cone (HKC) with equal numbers of bosonic and fermionic coordinates
are Ricci-flat, and hence, Calabi-Yau. We study deformations of the
supertwistor space induced from deformations of the HKC. We also discuss
general infinitesimal deformations that preserve Ricci-flatness.Comment: 13 pages, references and comments adde
A note on area variables in Regge calculus
We consider the possibility of setting up a new version of Regge calculus in
four dimensions with areas of triangles as the basic variables rather than the
edge-lengths. The difficulties and restrictions of this approach are discussed.Comment: 4 pages, amstex. Revision has minor changes and more precise
conclusion
Noncommutative Solitons: Moduli Spaces, Quantization, Finite Theta Effects and Stability
We find the N-soliton solution at infinite theta, as well as the metric on
the moduli space corresponding to spatial displacements of the solitons. We use
a perturbative expansion to incorporate the leading 1/theta corrections, and
find an effective short range attraction between solitons. We study the
stability of various solutions. We discuss the finite theta corrections to
scattering, and find metastable orbits. Upon quantization of the two-soliton
moduli space, for any finite theta, we find an s-wave bound state.Comment: Second revision: Discussions of translation zero-modes in section 4
and scales in section 5 improved; web addresses of movies changed. First
revision: Section 6 is rewritten (thanks to M. Headrick for pointing out a
mistake in the original version); some references and acknowledgements added.
21 pages, JHEP style, Hypertex, 1 figure, 3 MPEG's at:
http://www.physto.se/~unge/traj1.mpg http://www.physto.se/~unge/traj2.mpg
http://www.physto.se/~unge/traj3.mp
Superspace WZW Models and Black Holes
We show how to write an off-shell action for the
supersymmetric WZW model in terms of chiral and twisted chiral
multiplets. We discuss the supersymmetry of this model and exhibit the
superconformal current algebra. Finally, we show that the off-shell
formulation makes it possible to perform a duality transformation, which leads
to a supersymmetric sigma model on a manifold with a black hole type
singularity.Comment: 12 page
Three-dimensional N=2 supergravity theories: From superspace to components
For general off-shell N=2 supergravity-matter systems in three spacetime
dimensions, a formalism is developed to reduce the corresponding actions from
superspace to components. The component actions are explicitly computed in the
cases of Type I and Type II minimal supergravity formulations. We describe the
models for topologically massive supergravity which correspond to all the known
off-shell formulations for three-dimensional N=2 supergravity. We also present
a universal setting to construct supersymmetric backgrounds associated with
these off-shell supergravities.Comment: 79 pages; V3: minor corrections, version published in PR
- …