arXiv subjects

Marco Zagermann

Publications and source records attributed to Marco Zagermann.

40 records · Page 3Linked to original sources

arXiv2000

The Vacua of 5d,N=2 Gauged Yang-Mills/Einstein/Tensor Supergravity: Abelian Case

We give a detailed study of the critical points of the potentials of the simplest non-trivial N=2 gauged Yang-Mills/Einstein supergravity theories with tensor multiplets. The scalar field target space of these examples is SO(1,1)XSO(2,1)/SO(2). The possible gauge groups are SO(2)XU(1)_R and SO(1,1)XU(1)_R, where U(1)_R is a subgroup of the R-symmetry group SU(2)_R, and SO(2) and SO(1,1) are subgroups of the isometry group of the scalar manifold. The scalar potentials of these theories consist of a contribution from the U(1)_R gauging and a contribution that is due to the presence of the tensor fields. We find that the latter contribution can change the form of the supersymmetric extrema from maxima to saddle points. In addition, it leads to novel critical points not present in the corresponding gauged Yang-Mills/Einstein supergravity theories without the tensor multiplets. For the SO(2)XU(1)_R gauged theory these novel critical points correspond to anti-de Sitter ground states. For the non-compact SO(1,1)XU(1)_R gauging, the novel ground states are de Sitter. The analysis of the critical points of the potential carries over in a straightforward manner to the generic family of N=2 gauged Yang-Mills/Einstein supergravity theories coupled to tensor multiplets whose scalar manifolds are of the form SO(1,1)XSO(n-1,1)/SO(n-1).

hep-th↗

arXiv1999

The Gauging of Five-dimensional, N=2 Maxwell-Einstein Supergravity Theories coupled to Tensor Multiplets

We study the general gaugings of N=2 Maxwell-Einstein supergravity theories (MESGT) in five dimensions, extending and generalizing previous work. The global symmetries of these theories are of the form SU(2)_R X G, where SU(2)_R is the R-symmetry group of the N=2 Poincare superalgebra and G is the group of isometries of the scalar manifold that extend to symmetries of the full action. We first gauge a subgroup K of G by turning some of the vector fields into gauge fields of K while dualizing the remaining vector fields into tensor fields transforming in a non-trivial representation of K. Surprisingly, we find that the presence of tensor fields transforming non-trivially under the Yang-Mills gauge group leads to the introduction of a potential which does not admit an AdS ground state. Next we give the simultaneous gauging of the U(1)_R subgroup of SU(2)_R and a subgroup K of G in the presence of K-charged tensor multiplets. The potential introduced by the simultaneous gauging is the sum of the potentials introduced by gauging K and U(1)_R separately. We present a list of possible gauge groups K and the corresponding representations of tensor fields. For the exceptional supergravity we find that one can gauge the SO^*(6) subgroup of the isometry group E_{6(-26)} of the scalar manifold if one dualizes 12 of the vector fields to tensor fields just as in the gauged N=8 supergravity.

hep-th↗

arXiv1999

Dimensionally Reduced Gravity, Hermitian Symmetric Spaces and the Ashtekar Variables

Dimensional reductions of various higher dimensional (super)gravity theories lead to effectively two-dimensional field theories described by gravity coupled G/H nonlinear sigma-models. We show that a new set of complexified variables can be introduced when G/H is a Hermitian symmetric space. This generalizes an earlier construction that grew out of the Ashtekar formulation of two Killing vector reduced pure 4d general relativity. Apart from giving some new insights into dimensional reductions of higher dimensional (super)gravity theories, these Ashtekar-type variables offer several technical advantages in the context of the exact quantization of these models. As an application, an infinite set of conserved charges is constructed. Our results might serve as a starting point for probing the quantum equivalence of the Ashtekar and the metric formalism within a non-trivial midi-superspace model of quantum gravity.

gr-qc↗

arXiv1997

Metric Versus Ashtekar Variables in Two Killing Field Reduced Gravity

The relation between the SL(2,R)/SO(2)- and the SL(2,C)-chiral model that naturally arise within the metric respectively the Ashtekar formulation of two Killing field reduced Einstein gravity is revealed. Both chiral models turn out to be completely equivalent even though the transition from the coset- to the SL(2,C)-model is accompanied by a disappearance of the non-ultralocal terms in the Poisson brackets.

gr-qc↗