We have a diverse department membership from many different locations around the world.
Mon, 20 May 2019

14:15 - 15:15
L4

Stratifications and coarse moduli spaces for the stack of Higgs bundles

Eloise Hamilton
(Oxford)
Abstract

The stack of Higgs bundles of a given rank and degree over a non-singular projective curve can be stratified in two ways: according to its Higgs Harder-Narasimhan type (its instability type) and according to the Harder-Narasimhan type of the underlying vector bundle (instability type of the underlying bundle). The semistable stratum is an open stratum of the former and admits a coarse moduli space, namely the moduli space of semistable Higgs bundles. It can be constructed using Geometric Invariant Theory (GIT) and is a widely studied moduli space due to its rich geometric structure.

In this talk I will explain how recent advances in Non-Reductive GIT can be used to refine the Higgs Harder-Narasimhan and Harder-Narasimhan stratifications in such a way that each refined stratum admits a coarse moduli space. I will explicitly describe these refined stratifications and their intersection in the case of rank 2 Higgs bundles, and discuss the topology and geometry of the corresponding moduli spaces

Mon, 10 Jun 2019

14:15 - 15:15
L4

Moduli of polarised varieties via canonical Kähler metrics

Ruadhai Dervan
(Cambridge)
Abstract

Moduli spaces of polarised varieties (varieties together with an ample line bundle) are not Hausdorff in general. A basic goal of algebraic geometry is to construct a Hausdorff moduli space of some nice class of polarised varieties. I will discuss how one can achieve this goal using the theory of canonical Kähler metrics. In addition I will discuss some fundamental properties of this moduli space, for example the existence of a Weil-Petersson type Kähler metric. This is joint work with Philipp Naumann.

Maser radiation from collisionless shocks: application to astrophysical jets
Speirs, D Ronald, K Phelps, A Rigby, A Cross, J Kozlowski, P Miniati, F Oliver, M Sarkar, S Tzeferacos, P Gregori, G al., E High Power Laser Science and Engineering volume 7 (14 Mar 2019)
Search for non-relativistic magnetic monopoles with IceCube: IceCube Collaboration (vol 74, 2938, 2014)
Aartsen, M Abbasi, R Ackermann, M Adams, J Aguilar, J Ahlers, M Altmann, D Arguelles, C Arlen, T Auffenberg, J Bai, X Baker, M Barwick, S Baum, V Bay, R Beatty, J Tjus, J Becker, K Benabderrahmane, M BenZvi, S Berghaus, P Berley, D Bernardini, E Bernhard, A Besson, D Binder, G Bindig, D Bissok, M Blaufuss, E Blumenthal, J Boersma, D Bohm, C Bose, D Boeser, S Botner, O Brayeur, L Bretz, H Brown, A Bruijn, R Casey, J Casier, M Chirkin, D Christov, A Christy, B Clark, K Classen, L Clevermann, F Coenders, S Cohen, S Cowen, D Silva, A Danninger, M Daughhetee, J Davis, J Day, M de Andre, J De Clercq, C De Ridder, S Desiati, P de Vries, K de With, M DeYoung, T Diaz-Velez, J Dunkman, M Eagan, R Eberhardt, B Eichmann, B Eisch, J Euler, S Evenson, P Fadiran, O Fazely, A Fedynitch, A Feintzeig, J Feusels, T Filimonov, K Finley, C Fischer-Wasels, T Flis, S Franckowiak, A Frantzen, K Fuchs, T Gaisser, T Gallagher, J Gerhardt, L Gladstone, L Gluesenkamp, T Goldschmidt, A Golup, G Gonzalez, J Goodman, J Gora, D Grandmont, D Grant, D Gretskov, P Groh, J Gross, A Ha, C Haack, C Ismail, A Hallen, P Hallgren, A Halzen, F Hanson, K Hebecker, D Heereman, D Heinen, D Helbing, K Hellauer, R Hickford, S Hill, G Hoffman, K Hoffmann, R Homeier, A Hoshina, K Huang, F Huelsnitz, W Hulth, P Hultqvist, K Hussain, S Ishihara, A Jacobi, E Jacobsen, J Jagielski, K Japaridze, G Jero, K Jlelati, O Kaminsky, B Kappes, A Karg, T Karle, A Kauer, M Kelley, J Kiryluk, J Klaes, J Klein, S Koehne, J Kohnen, G Kolanoski, H Kopke, L Kopper, C Kopper, S Koskinen, D Kowalski, M Krasberg, M Kriesten, A Krings, K Kroll, G Kunnen, J Kurahashi, N Kuwabara, T Labare, M Landsman, H Larson, M Lesiak-Bzdak, M Leuermann, M Leute, J Luenemann, J Macias, O Madsen, J Maggi, G Maruyama, R Mase, K Matis, H McNally, F Meagher, K Meli, A Merck, M Meures, T Miarecki, S Middell, E Milke, N Miller, J Mohrmann, L Montaruli, T Morse, R Nahnhauer, R Naumann, U Niederhausen, H Nowicki, S Nygren, D Obertacke, A Odrowski, S Olivas, A Omairat, A O'Murchadha, A Palczewski, T Paul, L Pepper, J de los Heros, C Pfendner, C Pieloth, D Pinat, E Posselt, J Price, P Przybylski, G Quinnan, M Raedel, L Rameez, M Rawlins, K Redl, P Reimann, R Resconi, E Rhode, W Ribordy, M Richman, M Riedel, B Robertson, S Rodrigues, J Rott, C Ruhe, T Ruzybayev, B Ryckbosch, D Saba, S Sander, H Santander, M Sarkar, S Schatto, K Scheriau, F Schmidt, T Schmitz, M Schoenen, S Schoeneberg, S Schoenwald, A Schukraft, A Schulte, L Schulz, O Seckel, D Sestayo, Y Seunarine, S Shanidze, R Sheremata, C Smith, M Soldin, D Spiczak, G Spiering, C Stamatikos, M Stanev, T Stanisha, N Stasik, A Stezelberger, T Stokstad, R Stoessl, A Strahler, E Stroem, R Strotjohann, N Sullivan, G Taavola, H Taboada, I Tamburro, A Tepe, A Ter-Antonyan, S Tesic, G Tilav, S Toale, P Tobin, M Toscano, S Tselengidou, M Unger, E Usner, M Vallecorsa, S van Eijndhoven, N van Santen, J Vehring, M Voge, M Vraeghe, M Walck, C Wallraff, M Weaver, C Wellons, M Wendt, C Westerhoff, S Whelan, B Whitehorn, N Wiebe, K Wiebusch, C Williams, D Wissing, H Wolf, M Wood, T Woschnagg, K Xu, D Xu, X Yanez, J Yodh, G Yoshida, S Zarzhitsky, P Ziemann, J Zierke, S Zoll, M Collaboration, I EUROPEAN PHYSICAL JOURNAL C volume 79 issue 2 (08 Feb 2019) http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000458195800002&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=4fd6f7d59a501f9b8bac2be37914c43e
Mon, 04 Mar 2019
12:45
L5

Gauge Theory and Boundary Integrability

David Skinner
(Cambridge)
Abstract

Costello Yamazaki and Witten have proposed a new understanding of quantum integrable systems coming from a variant of Chern-Simons theory living on a product of two Riemann surfaces. I’ll review their work, and show how it can be extended to the case of integrable systems with boundary. The boundary Yang-Baxter Equations, twisted Yangians and Sklyanin determinants all have natural interpretations in terms of line operators in the theory.

Mon, 25 Feb 2019
12:45
L5

The Laplacian flow in G_2 geometry

Jason Lotay
(Oxford)
Abstract

Finding Riemannian metrics with holonomy G_2 is a challenging problem with links in mathematics to Einstein metrics and area-minimizing submanifolds, and to M-theory in theoretical physics.  I will provide a brief survey on recent progress towards studying this problem using a geometric flow approach, including connections to calibrated fibrations.

The Oxford Mathematics educational experience is a journey, a journey like any other educational experience. It builds on what you learn at school. It is not unfamiliar and we don't want it to invisible. But it has aspects that are different. One of these is the tutorial system. Students have lectures. But they also have tutorials based on those lectures where they sit, usually in pairs, with a tutor, go through their work and, critically, get to ask questions. It is their tutorial.

Tue, 26 Feb 2019

14:30 - 15:00
L3

Multispectral snapshot demosaicing via non-convex matrix completion

Simon Vary
(Oxford)
Abstract

Snapshot mosaic multispectral imagery acquires an undersampled data cube by acquiring a single spectral measurement per spatial pixel. Sensors which acquire p frequencies, therefore, suffer from severe 1/p undersampling of the full data cube.  We show that the missing entries can be accurately imputed using non-convex techniques from sparse approximation and matrix completion initialised with traditional demosaicing algorithms.

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