Physics

We continue a program of developing a new method for computing two-loop amplitudes based on generalized unitarity. In this approach, the two-loop amplitude is expanded in a basis of integrals, and the coefficients of the integrals are computed from...

In this talk I will discuss a deformation of the CP^{N-1} sigma model. Bosonic and fermonic formulations of the deformed model will be presented and conditions for which the theory appears to be quantum integrability will be spelled out...

The central drive of the analytic S-matrix program is to determine scattering amplitudes in any given theory from symmetries and analytic properties. This program led for instance to the birth of string theory with Veneziano's amplitude. Many recent...

The loop approach to quantum gravity has developed considerably during the last few years, especially in its covariant ('spinfoam') version. I present the current definition of the theory and the results that have been proven. I discuss what I...