The CFT dual of AdS gravity with torsion

We consider the Mielke-Baekler model of three-dimensional AdS gravity with torsion, which has gravitational and translational Chern-Simons terms in addition to the usual Einstein-Hilbert action with cosmological constant. It is shown that the topological nature of the model leads to a finite Fefferman-Graham expansion. We derive the holographic stress tensor and the associated Ward identities and show that, due to the asymmetry of the left- and right-moving central charges, a Lorentz anomaly appears in the dual conformal field theory. Both the consistent and the covariant Weyl and Lorentz anomaly are determined, and the Wess-Zumino consistency conditions for the former are verified. Moreover we consider the most general solution with flat boundary geometry, which describes left-and right-moving gravitational waves on AdS_3 with torsion, and shew that in this case the holographic energy-momentum tensor is given by the wave profiles. The anomalous transformation laws of the wave profiles under diffeomorphisms preserving the asymptotic form of the bulk solution yield the central charges of the dual CFT and confirm the results that appeared earlier on in the literature. We finally comment on some points concerning the microstate counting for the Riemann-Cartan black hole.Comment: 17 pages, uses JHEP3.cls. References added, minor errors correcte

Covariant description of the black hole entropy in 3D gravity

We study the entropy of the black hole with torsion using the covariant form of the partition function. The regularization of infinities appearing in the semiclassical calculation is shown to be consistent with the grand canonical boundary conditions. The correct value for the black hole entropy is obtained provided the black hole manifold has two boundaries, one at infinity and one at the horizon. However, one can construct special coordinate systems, in which the entropy is effectively associated with only one of these boundaries.Comment: 12 pages, LaTeX, v2: new material in section IV clarifies the effects pertaining to the use of different coordinate system

Black hole entropy in 3D gravity with torsion

The role of torsion in quantum three-dimensional gravity is investigated by studying the partition function of the Euclidean theory in Riemann-Cartan spacetime. The entropy of the black hole with torsion is found to differ from the standard Bekenstein-Hawking result, but its form is in complete agreement with the first law of black hole thermodynamics.Comment: 17 pages, RevTeX, minor revision

Noncommutative gauge theory using covariant star product defined between Lie-valued differential forms

We develop an internal gauge theory using a covariant star product. The space-time is a symplectic manifold endowed only with torsion but no curvature. It is shown that, in order to assure the restrictions imposed by the associativity property of the star product, the torsion of the space-time has to be covariant constant. An illustrative example is given and it is concluded that in this case the conditions necessary to define a covariant star product on a symplectic manifold completely determine its connection.Comment: AMS-LaTeX 19 pages. v2: corrections in language and equations (typos), expanded sections 3-5, added references. v3: minor presentational and grammatical corrections, completed, corrected and reordered some references

AdS-inspired noncommutative gravity on the Moyal plane

We consider noncommutative gravity on a space with canonical noncommutativity that is based on the commutative MacDowell-Mansouri action. Gravity is treated as gauge theory of the noncommutative $SO(1,3)_\star$ group and the Seiberg-Witten (SW) map is used to express noncommutative fields in terms of the corresponding commutative fields. In the commutative limit the noncommutative action reduces to the Einstein-Hilbert action plus the cosmological term and the topological Gauss-Bonnet term. After the SW expansion in the noncommutative parameter the first order correction to the action, as expected, vanishes. We calculate the second order correction and write it in a manifestly gauge covariant way.Comment: 22 pages, no figures, final versio

2D Induced Gravity as an Effective WZNW System

We introduced a dynamical system given by a difference of two simple SL(2,R) WZNW actions in 2D, and defined the related gauge theory in a consistent way. It is shown that gauge symmetry can be fixed in such a way that, after integrating out some dynamical variables in the functional integral, one obtains the induced gravity action.Comment: LaTeX, 16 page

2D induced gravity from canonically gauged WZNW system

Starting from the Kac--Moody structure of the WZNW model for SL(2,R) and using the general canonical formalism, we formulate a gauge theory invariant under local SL(2,R) x SL(2,R) and diffeomorphisms. This theory represents a gauge extension of the WZNW system, defined by a difference of two simple WZNW actions. By performing a partial gauge fixing and integrating out some dynamical variables, we prove that the resulting effective theory coincides with the induced gravity in 2D. The geometric properties of the induced gravity are obtained out of the gauge properties of the WZNW system with the help of the Dirac bracket formalism.Comment: LaTeX, 21 page

A Tverberg type theorem for matroids

Let b(M) denote the maximal number of disjoint bases in a matroid M. It is shown that if M is a matroid of rank d+1, then for any continuous map f from the matroidal complex M into the d-dimensional Euclidean space there exist t \geq \sqrt{b(M)}/4 disjoint independent sets \sigma_1,\ldots,\sigma_t \in M such that \bigcap_{i=1}^t f(\sigma_i) \neq \emptyset.Comment: This article is due to be published in the collection of papers "A Journey through Discrete Mathematics. A Tribute to Jiri Matousek" edited by Martin Loebl, Jaroslav Nesetril and Robin Thomas, due to be published by Springe

Arterijska vaskularizacija mozga malog zelenog majmuna, Cercopithecus aethiops sabeus

Cell cultures from the small green monkey are used for the cultivation of poliovirus in the manufacture of vaccines against poliomyelitis. In addition kidney cultures from the same monkey serve for detection of the virus in biological material. This was the main reason that prompted us to undertake a study of one part of the monkey’s cardiosvascular system and thus contribute to a better understanding of the structure of its body.Glavni krvni sudovi koji dovode arterijsku krv u mozak su A.carotis interna i A. vertebralis. Spajanjem leve i desne kičmene arterije (A. vertebralis sinistra et dextra) nastaje A. basilaris cerebri. A. carotis interna sinistra et dextra pružaju se kroz parafaringealni prostor prema lobanjskoj duplji, u koju ulaze pošto prođu kroz karotidne kanale (canales carotici) piramide slepoočne kosti u kavernozni sinus u kome se povezuju obe Aa. carotides preko A. intercarotica caudalis. Grane A. carotis internae su: A. ophthalmica, A. cerebri media, A. communicans caudalis. A.ophthalmica dovodi krv u optičke i pomoćne delove oka. A. cerebri media daje grane koje ulaze u moždanu masu i dovodi krv u lateralnu površinu moždane hemisfere. A. communicans caudalis povezuje zadnju moždanu arteriju (A. cerebri caudalis) sa unutrašnjom karotidnom arterijom i daje grane za vaskularizaciju hipotalamusa. A.cerebri rostralis je produžetak stabla unutrašnje karotidne arterije. Ona se spaja sa odgovarajućom granom druge strane ispred Chiasma opticum. Iz ovog spoja nastaje A. cerebri rostralis communis. Od A. cerebri rostralis odvajaju se površne i duboke grane koje ulaze u moždanu masu. A. cerebri caudalis, A. communicans caudalis i A. cerebri rostralis obrazuju oko hipofize i raskršća vidnih nerava arterijski krug (Circulus arteriosus Willisi)

Canonical approach to 2D WZNW model, non-abelian bosonization and anomalies

The gauged WZNW model has been derived as an effective action, whose Poisson bracket algebra of the constraints is isomorphic to the commutator algebra of operators in quantized fermionic theory. As a consequence, the hamiltonian as well as usual lagrangian non-abelian bosonization rules have been obtained, for the chiral currents and for the chiral densities. The expression for the anomaly has been obtained as a function of the Schwinger term, using canonical methods.Comment: RevTex, 23 page