July 13, 2006
In this PhD Thesis, supersymmetry and its formulation in the context of D=11 supergravity is discussed from several perspectives. The role of generalized holonomy as a classification tool of supersymmetric supergravity solutions is reviewed, with particular emphasis on how successive supercovariant derivatives of the generalized curvature may be needed to properly define the generalized holonomy algebra. The generalized curvature is also shown to contain the supergravity equations of motion, even in the non-vanishing gravitino case. The underlying gauge symmetry of D=11 supergravity is discussed and argued to become manifest when its three-form field A_3 is expressed through a set of one-form gauge fields, associated with the generators of a suitable family of enlarged supersymmetry algebras. This family is related to osp(1|32) through expansion, a method to obtain new Lie (super)algebras of increasing dimensions from given ones. The analysis of the underlying gauge symmetry of D=11 supergravity leads naturally to enlarged supersymmetry algebras and superspaces making, thus, natural to consider actions for objects moving in such spaces. In particular, a string moving in tensorial space is discussed, describing the excitations of a state preserving 30 out of 32 supersymmetries (hence composed of two preons, hypothetical constituents of M Theory preserving 31 supersymmetries). A G-frame method is also discussed to study hypothetical preonic solutions of supergravity.
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December 22, 2003
We develop the BPS preon conjecture to analyze the supersymmetric solutions of D=11 supergravity. By relating the notions of Killing spinors and BPS preons, we develop a moving G-frame method (G=GL(32,R), SL(32,R) or Sp(32,R)) to analyze their associated generalized holonomies. As a first application we derive here the equations determining the generalized holonomies of k/32 supersymmetric solutions and, in particular, those solving the necessary conditions for the existence ...
May 5, 2003
Supersymmetric solutions of 11-dimensional supergravity can be classified according to the holonomy of the supercovariant derivative arising in the Killing spinor condition. It is shown that the holonomy must be contained in $\SL(32,\R)$. The holonomies of solutions with flux are discussed and examples are analysed. In extending to M-theory, account has to be taken of the phenomenon of ` supersymmetry without supersymmetry'. It is argued that including the fermionic degrees o...
July 2, 2001
The quest for unification of particles and fields and for reconciliation of Quantum Mechanics and General Relativity has led us to gauge theories, string theories, supersymmetry and higher-extended objects: membranes... Our spacetime is quantum mechanical but it admits semiclassical descriptions of various ``complementary'' kinds that could be valid approximations in various circumstances. One of them might be supergravity in 11 dimensions the largest known interacting theory...
November 22, 2006
This thesis deals with the construction of an eleven-dimensional gauge theory, off-shell invariant, for the M Algebra. The theory is built using a Transgression Form as a Lagrangian. In order to accomplish this, one must first analyze the general construction of Transgression Gauge Field Theories, for an arbitrary symmetry group (Chapter 3). Some interesting results regarding this point are (1) the calculation of Noether Charges which are off-shell conserved, (2) the associ...
February 19, 2018
The purpose of my PhD thesis is to investigate different group theoretical and geometrical aspects of supergravity theories. To this aim, several research topics are explored: On one side, the construction of supergravity models in diverse space-time dimensions, including the study of boundary contributions, and the disclosure of the hidden gauge structure of these theories; on the other side, the analysis of the algebraic links among different superalgebras related to superg...
September 8, 2004
The underlying gauge group structure of the D=11 Cremmer-Julia-Scherk supergravity becomes manifest when its three-form field A_3 is expressed through a set of one-form gauge fields. These are associated with the generators of the elements of a family of enlarged supersymmetry algebras $\tilde{\mathfrak{E}}^{(528|32+32)}(s)$ parametrized by a real number s. We study in detail the composite structure of A_3 extending previous results by D'Auria and Fr\'e, stress the equivalenc...
October 10, 2003
This Ph.D. thesis was submitted to the Catholic University of Leuven. We discuss two main topics: various formulations of duality-symmetric theories and D=5 supergravity (both construction and supersymmetric solutions). The thesis is structured as follows: Ch. 1 Introduction; Ch. 2 String theory toolkit; Ch. 3 Free duality-symmetric theories; Ch. 4 Interacting duality-symmetric theories; Ch. 5 Conformal supergravity in D=5: Weyl multiplets; Ch. 6 Conformal supergravity in D=5...
January 10, 2002
In 1981, covariantly constant spinors were introduced into Kaluza-Klein theory as a way of counting the number of supersymmetries surviving compactification. These are related to the holonomy group of the compactifying manifold. The first non-trivial example was provided in 1982 by D=11 supergravity on the squashed S7, whose G2 holonomy yields N=1 in D=4. In 1983, another example was provided by D=11 supergravity on K3, whose SU(2) holonomy yields half the maximum supersymmet...
May 15, 2003
A theoretical analysis of higher-order corrections to D=11 supergravity is given in a superspace framework. It is shown that any deformation of D=11 supergravity for which the lowest-dimensional component of the four-form $G_4$ vanishes is trivial. This implies that the equations of motion of D=11 supergravity are specified by an element of a certain spinorial cohomology group and generalises previous results obtained using spinorial or pure spinor cohomology to the fully non...
December 12, 2013
In this thesis we have obtained and studied the complete set of superfield equations of motion for the interacting system of four-dimensional supermembrane and dynamical scalar multiplet. This study provides the first example of superfield equations for interacting system involving matter superfields and extended supersymmetric object, as well as the first set of superfield equations of motion for a dynamical system which includes supermembrane. The action for a supermembrane...