## Séminaire de Physique Théorique

**Particles and Strings in (Topological) Quantum Gravity**

Winston Fairbairn

Monday 03 December 2007 14:00 - Tours - Salle 1180 (Bât E2)

**Résumé :**

Solving Einstein's three dimensional field equations in the presence of point-like matter leads to everywhere flat solutions except at the location of the particles where local conical defects appear. Accordingly, point particles in three dimensions can be entirely re-thought of as local properties of space-time curvature. This is the starting point for many recent developments in the loop/spin-foam approach to the quantization of matter coupled to 3d gravity. After a general review of loop quantum gravity and spin-foam models, I will describe the main three-dimensional results. Then, I will discuss possible generalizations to higher dimensions. I will show how one is naturally led, in the context of four dimensional topological gravity (BF theory), to consider extended objects and will discuss the quantization of the resulting models.

**Liens :**