Past Quantum Field Theory Seminar

29 November 2011
12:00
Nazim Bouatta (DAMTP)
Abstract
In recent decades, quantum field theory (QFT) has become the framework for several basic and outstandingly successful physical theories. Indeed, it has become the lingua franca of entire branches of physics and even mathematics. The universal scope of QFT opens fascinating opportunities for philosophy. Accordingly, although the philosophy of physics has been dominated by the analysis of quantum mechanics, relativity and thermo-statistical physics, several philosophers have recently undertaken conceptual analyses of QFT. One common feature of these analyses is the emphasis on rigorous approaches, such as algebraic and constructive QFT; as against the more heuristic and physical formulations of QFT in terms of functional (also knows as: path) integrals. However, I will follow the example of some recent mathematicians such as Atiyah, Connes and Kontsevich, who have adopted a remarkable pragmatism and opportunism with regard to heuristic QFT, not corseted by rigor (as Connes remarks). I will conceptually discuss the advances that have marked heuristic QFT, by analysing some of the key ideas that accompanied its development.  I will also discuss the interactions between these concepts in the various relevant fields, such as particle physics, statistical mechanics, gravity and geometry. 
  • Quantum Field Theory Seminar
15 November 2011
12:00
Jean Alexandre (KCL)
Abstract
Attractive features of Lifshitz type theories are described with different examples, as the improvement of graphs convergence, the introduction of new renormalizable interactions, dynamical mass generation, asymptotic freedom, and other features related to more specific models. On the other hand, problems with the expected emergence of Lorentz symmetry in the IR are discussed, related to the different effective light cones seen by different particles when they interact.
  • Quantum Field Theory Seminar
25 October 2011
12:00
Dorje C. Brody (Brunel University)
Abstract
Quaternionic quantum Hamiltonians describing nonrelativistic spin particles require the ambient physical space to have five dimensions. The quantum dynamics of a spin-1/2 particle system characterised by a generic such Hamiltonian is described. There exists, within the structure of quaternionic quantum mechanics, a canonical reduction to three spatial dimensions upon which standard quantum theory is retrieved. In this dimensional reduction, three of the five dynamical variables oscillate around a cylinder, thus behaving in a quasi one-dimensional manner at large distances. An analogous mechanism exists in the case of octavic Hamiltonians, where the ambient physical space has nine dimensions. Possible experimental tests in search for the signature of extra dimensions at low energies are briefly discussed. (Talk based on joint work with Eva-Maria Graefe, Imperial.)
  • Quantum Field Theory Seminar
17 May 2011
12:00
Jamie Vicary (Comlab)
Abstract

I will present some new results on classifying 123 TQFTs,
using a 2-categorical approach. The invariants defined by a TQFT are
described using a new graphical calculus, which makes them easier to
define and to work with. Some new and interesting physical phenomena
are brought out by this perspective, which we investigate. I will
finish by banishing some TQFT myths! This talk is based on joint work
with Bruce Bartlett, Chris Schommer-Pries and Chris Douglas.

  • Quantum Field Theory Seminar

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