Chern-simons (Super)gravity

Book excerpt: 'The authors provide an up-to-date, well-organised background and essential elements of supergravity notions as well as all relevant aspects of Chern-Simons forms in gravitation. The book is a self-contained, informative, and much-needed broad introduction into the latest quantum gravity concepts, with a main focus on Chern-Simons gravity and supersymmetry … The book represents a comprehensive and systematic pedagogical exposition on gravitational Chern-Simons (Super)gravity theories, their applications, together with a selection of related recent developments in the field.'Contemporary PhysicsThis book grew out of a set of lecture notes on gravitational Chern-Simons (CS) theories developed over the past decade for several schools and different audiences including graduate students and researchers.CS theories are gauge-invariant theories that can include gravity consistently. They are only defined in odd dimensions and represent a very special class of theories in the Lovelock family. Lovelock gravitation theories are the natural extensions of General Relativity for dimensions greater than four that yield second-order field equations for the metric. These theories also admit local supersymmetric extensions where supersymmetry is an off-shell symmetry of the action, as in a standard gauge theory.Apart from the arguments of mathematical elegance and beauty, the gravitational CS actions are exceptionally endowed with physical attributes that suggest the viability of a quantum interpretation. CS theories are gauge-invariant, scale-invariant and background independent; they have no dimensional coupling constants. All constants in the Lagrangian are fixed rational coefficients that cannot be adjusted without destroying gauge invariance. This exceptional status of CS systems makes them classically interesting to study, and quantum mechanically intriguing and promising.