Holst-MacDowell-Mansouri action for (extended) supergravity with boundaries and super Chern-Simons theory

Abstract

In this article, the Cartan geometric approach toward (extended) supergravity in the presence of boundaries will be discussed. In particular, based on new developments in this field, we will derive the Holst variant of the MacDowell-Mansouri action for N = 1 and N = 2 pure AdS supergravity in D = 4 for arbitrary Barbero-Immirzi parameters. This action turns out to play a crucial role in context of boundaries in the framework of supergravity if one imposes supersymmetry invariance at the boundary. For the N = 2 case, it follows that this amounts to the introduction of a θ-topological term to the Yang-Mills sector which explicitly depends on the Barbero-Immirzi parameter. This shows the close connection between this parameter and the θ-ambiguity of gauge theory. We will also discuss the chiral limit of the theory, which turns out to possess some very special properties such as the manifest invariance of the resulting action under an enlarged gauge symmetry. Moreover, we will show that demanding supersymmetry invariance at the boundary yields a boundary term corresponding to a super Chern-Simons theory with OSp(N |2) gauge group. In this context, we will also derive boundary conditions that couple boundary and bulk degrees of freedom and show equivalence to the results found in the D'Auria-Fré approach in context of the non-chiral theory. These results provide a step towards of quantum description of supersymmetric black holes in the framework of loop quantum gravity.

On the geometric approach to the boundary problem in supergravity

“…Further applications of the superspace geometric approach to supergravity in the presence of a non-trivial boundary were subsequently presented in [37,38], where, however, models with an enlarged definition of supergravity and exhibiting a generalized cosmological constant [39-45] 1 were considered. Let us also mention that recently the geometric approach to N = 1 and N = 2 supergravity theories with boundary was applied in [46] in the context of loop quantum gravity to derive the so-called Holst-MacDowell-Mansouri action (involving, in particular, a parity odd term named Hojman term [47,48], and also known as Holst term [49]).…”

$\mathcal{N}=2$ Extended MacDowell-Mansouri Supergravity

“…From this perspective, the group G puts together the structure group H and fiber sections, unifying the H-principal bundle and the associated fiber bundle with sections in f. For a more rigorous exposition of these subjects see e.g. [11,12].…”