Talk by Prof. Emil Mottola

Speaker: Prof. Emil Mottola, Theoretical Division, Los Alamos National Laboratory. 
Title: Instability of de Sitter Space, the Schwinger effect and Dynamical Dark energy

Date: Wednesday December 3rd
Time: 11am
Place: Room 241 Nicholson

Global de Sitter space is unstable to particle creation. The O(4, 1) de Sitter invariant state is a 
de finite phase coherent superposition of particle and anti-particle solutions in both the asymptotic 
past and future, and therefore is not a true vacuum state. In the closely analogous case of a constant, 
uniform electric field, a time symmetric state analogous to the de Sitter invariant one is constructed, 
which is also not a stable vacuum state, because of the Schwinger effect. The role of a quantum anomaly
in the growth of perturbations and symmetry breaking is emphasized in both cases. Consequences
of this result for cosmology and the problem of vacuum dark energy will be discussed.

Talk by Suzanne Lanery

Speaker: Suzanne Lanery, Friedrich Alexander Universitaet, Erlangen.
Title: Extending the phase space of loop quantum gravity
Date: Monday December 1st
Time: 3pm
Place: Room 241 Nicholson

Abstract: Instead of formulating the state space of a quantum field theory over a single big Hilbert space, it has been proposed by Jerzy Kijowski to describe quantum states as projective families of density matrices over a collection of smaller, simpler Hilbert spaces. I will discuss the physical motivations for this approach and explain how it can be implemented in the context of LQG. While the resulting state space forms a natural extension of the Ashtekar-Lewandowski Hilbert space, it treats position and momentum variables on equal footing. This paves the way for the construction of semi-classical states beyond fixed graph level, and eventually for the derivation of symmetry reduced models from full LQG.

Talk by Cohl Furey

Date: Monday, November 24th 2014
Time: 3pm
Place: 241 Nicholson
Speaker: Cohl Furey, Perimeter Institute

Title:  Charge quantization from a number operator

Abstract:

Here, we explain how an unexpected algebraic structure, the division algebras, can be seen to underlie a generation of quarks and leptons.  From this new vantage point, electrons and quarks are simply excitations from the neutrino, which formally plays the role of a vacuum state.

Using the ladder operators which exist within the system, we build a number operator in the usual way. It turns out that this number operator, divided by 3, mirrors the behaviour of electric charge. As a result, we see that electric charge is quantized because number operators can only take on integer values.

Finally, we show a simple hermitian form, which leads uniquely to the nine generators of SUc(3) and Uem(1). This gives a direct route to the two unbroken gauge symmetries of the standard model.