# Next Week

Here is a selection of seminars that might be of interest to string theorists in Oxford:

On Monday at 14:00 in Dennis Sciama Lecture Theatre, a seminar in the Astrophysics Colloquia series:
No Seminar (Bank Holiday)
On Monday at 14:15 in L4, a seminar in the Geometry and Analysis series:
Philip Boalch (Orsay)
Nonabelian Hodge spaces and nonlinear representation theory
Further information: The theory of connections on curves and Hitchin systems is something like a “global theory of Lie groups”, where one works over a Riemann surface rather than just at a point. We’ll describe how one can take this analogy a few steps further by attempting to make precise the class of rich geometric objects that appear in this story (including the non-compact case), and discuss their classification, outlining a theory of “Dynkin diagrams” as a step towards classifying some examples of such objects.
On Tuesday at 11:30 in Bipac Seminar Room, DWB, a seminar in the Cosmology series:
Andrew Pontzen (UCL)
Insights into non-linear structure growth from inverted initial conditions
On Tuesday at 12:00 in L4, a seminar in the Relativity series:
Paul Townsend (DAMTP Cambridge)
Supertwistors: the massless, the massive, and the AdS
Further information: Some recent applications of supertwistors to superparticle mechanics will be reviewed. First: Supertwistors allow a simple quantization of the  N-extended 4D massless superparticle, and peculiarities of massless 4D supermultiplets can then be explained by considering the quantum fate of a classical worldline CPT'' symmetry. For N=1 there is a global CPT anomaly, which explains why there is no CPT self-conjugate supermultiplet. For N=2 there is no anomaly but a Kramers degeneracy explains the doubling of states in the CPT self-conjugate hypermultiplet. Second: the bi-supertwistor formulation of the N-extended massive superparticle in 3D, 4D and 6D makes manifest a hidden’’ 2N-extended supersymmetry. It also has a simple expression in terms of hermitian 2x2 matrices over the associative division algebras R,C,H. Third: omission of the mass-shell constraint in this 3D,4D,6D bi-supertwistor action yields, as suggested  by holography, the action for a supergraviton in 4D,5D,7D AdS. Application to the near horizon AdSxS geometries of the M2,D3 and M5 brane confirms that the graviton supermultiplet has 128+128 polarisation states.
On Tuesday at 14:00 in DWB Fisher Room, a seminar in the Holography series:
Marika Taylor (U. Southampton)