Triangle Seminars

Abstract:
We review the role played by the Yangian symmetry generated by non-local charges in a range of integrable models, and in particular the non-linear sigma models, describing briefly the representation theory of the Yangian and its implications for physics. We explain how an integrable boundary naturally reduces this to a 'twisted
Yangian' symmetry.

Abstract:
The physics of glassy systems at low temperatures differs in striking and unexpected ways from that of their crystalline counterparts, in that thermal, transport and dynamic response properties exhibit unusual temperature variation. Atomic or molecular tunneling centers are believed to be at the origin of these phenomena, which show a remarkable degree of universality across a wide spectrum of diverse amorphous substances, ranging from window glass to polystyrene. We describe recent advances in understanding these phenomena, using a microscopic modelling approach. It has for the first time allowed to identify a mechanism responsible for the occurrence of tunneling systems, to characterize them quantitatively, and to provide a simple and transparent explanation for the unusual universality of glassy low temperature anomalies.

Abstract:
Witten's twistor string theory description of N=4 super Yang-Mills has led to much progress in perturbative Yang-Mills theory this year, with accumulating evidence for the localisation of scattering amplitudes in twistor space in various Yang-Mills theories. This talk will focus on the MHV diagram approach, which builds in localisation, and will describe work done at Queen Mary which shows how to define MHV diagrams at loop level. This has been successfully applied to give the general one-loop MHV amplitudes in N=4 and N=1 super Yang-Mills.