On gravitational defects, particles and strings

Abstract

We study the inclusion of point and string matter in the deSitter gauge theory, or MacDowell-Mansouri formulation of four dimensional gravity. We proceed by locally breaking the gauge symmetries of general relativity along worldlines and worldsheets embedded in the spacetime manifold. Restoring full gauge invariance introduces new dynamical fields which describe the dynamics of spinning matter coupled to gravity. We discuss the physical interpretation of the obtained formalism by studying the flat limit and the spinless case on arbitrary backgrounds. It turns out that the worldline action describes a massive spinning particle, while the worldsheet action contains the Nambu-Goto string augmented with spinning contributions. Finally, we study the gravity/matter variational problem and conclude by discussing potential applications of the formalism to the inclusion of the Nambu-Goto string in spinfoam models of four dimensional quantum gravity.

30 pages, no figures

References in corpus (8)

• 3d Quantum Gravity and Effective Non-Commutative Quantum Field Theory
• Ponzano-Regge model revisited III: Feynman diagrams and Effective field theory
• Spacetime geometry from algebra: spin foam models for non-perturbative quantum gravity
• so(4) Plebanski Action and Relativistic Spin Foam Model
• Particles as Wilson lines of gravitational field
• Extended matter coupled to BF theory
• Two-dimensional topological field theories coupled to four-dimensional BF theory
• Bosonic Description of Spinning Strings in $2+1$ Dimensions

Cited by in corpus (9)

• Loop Quantum Gravity a la Aharonov-Bohm
• Effective particle kinematics from Quantum Gravity
• Gauge Gravity: a forward-looking introduction
• The D^6 R^4 term from three loop maximal supergravity
• Discrete quantum geometries and their effective dimension
• Canonical Analysis of Algebraic String Actions
• Holographic Aspects of Even-Dimensional Topological Gravity
• Equivalence of the self-dual and Nambu-Goto strings
• Interactions in MacDowell-Mansouri Gravitation