11 research outputs found
Classical and Quantum Integrability of 2D Dilaton Gravities in Euclidean space
Euclidean dilaton gravity in two dimensions is studied exploiting its
representation as a complexified first order gravity model. All local classical
solutions are obtained. A global discussion reveals that for a given model only
a restricted class of topologies is consistent with the metric and the dilaton.
A particular case of string motivated Liouville gravity is studied in detail.
Path integral quantisation in generic Euclidean dilaton gravity is performed
non-perturbatively by analogy to the Minkowskian case.Comment: 27 p., LaTeX, v2: included new refs. and a footnot
Supersymmetric black holes in 2D dilaton supergravity: baldness and extremality
We present a systematic discussion of supersymmetric solutions of 2D dilaton
supergravity. In particular those solutions which retain at least half of the
supersymmetries are ground states with respect to the bosonic Casimir function
(essentially the ADM mass). Nevertheless, by tuning the prepotential
appropriately, black hole solutions may emerge with an arbitrary number of
Killing horizons. The absence of dilatino and gravitino hair is proven.
Moreover, the impossibility of supersymmetric dS ground states and of
nonextremal black holes is confirmed, even in the presence of a dilaton. In
these derivations the knowledge of the general analytic solution of 2D dilaton
supergravity plays an important role. The latter result is addressed in the
more general context of gPSMs which have no supergravity interpretation.
Finally it is demonstrated that the inclusion of non-minimally coupled
matter, a step which is already nontrivial by itself, does not change these
features in an essential way.Comment: 30 pages, LaTeX, v2: mayor revision (rearranged title, shortened
abstract, revised introduction, inserted section from appendix to main text,
added subsection with new material on non-SUGRA gPSMs, added clarifying
remarks at some places, updated references); v3: corrected minor misprints,
added note with a new referenc
An action for the exact string black hole
A local action is constructed describing the exact string black hole
discovered by Dijkgraaf, Verlinde and Verlinde in 1992. It turns out to be a
special 2D Maxwell-dilaton gravity theory, linear in curvature and field
strength. Two constants of motion exist: mass M>1, determined by the level k,
and U(1)-charge Q>0, determined by the value of the dilaton at the origin. ADM
mass, Hawking temperature T_H \propto \sqrt{1-1/M} and Bekenstein-Hawking
entropy are derived and studied in detail. Winding/momentum mode duality
implies the existence of a similar action, arising from a branch ambiguity,
which describes the exact string naked singularity. In the strong coupling
limit the solution dual to AdS_2 is found to be the 5D Schwarzschild black
hole. Some applications to black hole thermodynamics and 2D string theory are
discussed and generalizations - supersymmetric extension, coupling to matter
and critical collapse, quantization - are pointed out.Comment: 41 pages, 2 eps figures, dedicated to Wolfgang Kummer on occasion of
his Emeritierung; v2: added ref; v3: extended discussion in sections 3.2, 3.3
and at the end of 5.3 by adding 2 pages of clarifying text; updated refs;
corrected typo
The Complete Solution of 2D Superfield Supergravity from graded Poisson-Sigma Models and the Super Pointparticle
Recently an alternative description of 2d supergravities in terms of graded
Poisson-Sigma models (gPSM) has been given. As pointed out previously by the
present authors a certain subset of gPSMs can be interpreted as "genuine"
supergravity, fulfilling the well-known limits of supergravity, albeit deformed
by the dilaton field. In our present paper we show that precisely that class of
gPSMs corresponds one-to-one to the known dilaton supergravity superfield
theories presented a long time ago by Park and Strominger. Therefore, the
unique advantages of the gPSM approach can be exploited for the latter: We are
able to provide the first complete classical solution for any such theory. On
the other hand, the straightforward superfield formulation of the point
particle in a supergravity background can be translated back into the gPSM
frame, where "supergeodesics" can be discussed in terms of a minimal set of
supergravity field degrees of freedom. Further possible applications like the
(almost) trivial quantization are mentioned.Comment: 48 pages, 1 figure. v3: after final version, typos correcte