141 research outputs found
Twistor Spaces for QKT Manifolds
We find that the target space of two-dimensional (4,0) supersymmetric sigma
models with torsion coupled to (4,0) supergravity is a QKT manifold, that is, a
quaternionic K\"ahler manifold with torsion. We give four examples of
geodesically complete QKT manifolds one of which is a generalisation of the
LeBrun geometry. We then construct the twistor space associated with a QKT
manifold and show that under certain conditions it is a K\"ahler manifold with
a complex contact structure. We also show that, for every 4k-dimensional QKT
manifold, there is an associated 4(k+1)-dimensional hyper-K\"ahler one.Comment: 25 pages, phyzz
Гравитационный аналог статистической механики
Исследуется связь между релятивистской термодинамикой ранней Вселенной с метрикой Логунова и гравитационным аналогом статистической механики. Обнаружено, что обратимое во времени уравнение Лиувилля может иметь частное решение с нарушенной симметрией во времени
Solitons in 1+1 Dimensional Gauged Sigma Models
We study soliton solutions in 1+1 dimensional gauged sigma models, obtained
by dimensional reduction from its 2+1 dimensional counterparts. We show that
the Bogomol'nyi bound of these models can be expressed in terms of two
conserved charges in a similar way to that of the BPS dyons in 3+1 dimensions.
Purely magnetic vortices of the 2+1 dimensional completely gauged sigma model
appear as charged solitons in the corresponding 1+1 dimensional theory. The
scale invariance of these solitons is also broken because of the dimensional
reduction. We obtain exact static soliton solutions of these models saturating
the Bogomol'nyi bound.Comment: 21 pages, RevTeX, minor changes, version to appear in Physical Review
The BPS Domain Wall Solutions in Self-Dual Chern-Simons-Higgs Systems
We study domain wall solitons in the relativistic self-dual Chern-Simons
Higgs systems by the dimensional reduction method to two dimensional spacetime.
The Bogomolny bound on the energy is given by two conserved quantities in a
similar way that the energy bound for BPS dyons is set in some Yang-Mills-Higgs
systems in four dimensions. We find the explicit soliton configurations which
saturate the energy bound and their nonrelativistic counter parts. We also
discuss the underlying N=2 supersymmetry.Comment: 16 pages, LaTeX, no figure, a minor change in acknowledgment
Vanishing Theorems and String Backgrounds
We show various vanishing theorems for the cohomology groups of compact
hermitian manifolds for which the Bismut connection has (restricted) holonomy
contained in SU(n) and classify all such manifolds of dimension four. In this
way we provide necessary conditions for the existence of such structures on
hermitian manifolds. Then we apply our results to solutions of the string
equations and show that such solutions admit various cohomological restrictions
like for example that under certain natural assumptions the plurigenera vanish.
We also find that under some assumptions the string equations are equivalent to
the condition that a certain vector is parallel with respect to the Bismut
connection.Comment: 25 pages, Late
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