All Upcoming Events

On Thursday at 12:45 in L2, a seminar in the Strings Junior series:
Johan Henriksson
Higgs bundles
On Thursday at 13:00 in Dalitz Institute, a seminar in the Dalitz Seminar in Fundamental Physics series:
None (Oxford)
Cancelled
On Thursday at 16:00 in L6, a seminar in the Number Theory series:
Anna Cadoret (Université Paris 6 (IMJ-PRG))
The fundamental theorem of Weil II (for curves) with ultra product coefficients
Further information: l-adic cohomology was built to provide an etale cohomology with coefficients in a field of characteristic 0. This, via the Grothendieck trace formula, gives  a cohomological interpretation of L-functions - a fundamental tool in Deligne's theory of weights developed in Weil II. Instead of l-adic coefficients one can consider coefficients in ultra products of finite fields. I will state the fundamental theorem of Weil II for curves in this setting and explain briefly what are the difficulties to overcome to adjust Deligne's proof. I will then discuss how this ultra product variant of Weil II allows to extend to arbitrary coefficients  previous results of Gabber and Hui, Tamagawa and myself for constant $\mathbb{Z}_\ell$-coefficients.  For instance,  it implies that, in an $E$-rational compatible system of smooth $\overline{\mathbb{Q}}_\ell$-sheaves all what is true for $\overline{\mathbb{Q}}_\ell$-coefficients (semi simplicity, irreducibility, invariant dimensions etc) is true for $\overline{\mathbb{F}}_\ell$-coefficients provided $\ell$ is large enough or that the $\overline{\mathbb{Z}}_\ell$-models are unique with torsion-free cohomology provided $\ell$ is large enough.
On Thursday at 16:15 in Dennis Sciama Lecture Theatre, a seminar in the Theoretical Particle Physics series:
Christophe Grojean (DESY Hamburg)
Assessing the Higgs (self-)couplings
On Friday at 14:00 in Dennis Sciama Lecture Theatre, a seminar in the Theoretical Physics Colloquia series:
Thordur Jonsson (Iceland)
The dynamical triangulation approach to quantum gravity
On Monday at 12:45 in L3, a seminar in the String Theory series:
Albrecht Klemm (Bonn)
TBA
On Monday at 14:15 in L5, a seminar in the Geometry and Analysis series:
Matthias Wink (Oxford University)
Constructions of cohomogeneity one Ricci solitons
On Tuesday at 12:00 in L4, a seminar in the Relativity series:
Dhritiman Nandan (Edinburgh University)
Amplitude relations in Einstein-Yang-Mills theory
Further information: *I will discuss recent developments in the study of scattering amplitudes in Einstein-Yang-Mills theory. At tree level we find new structures at higher order collinear limits and novel connections with amplitudes in Yang-Mills theory using the CHY formalism. Finally I will comment on unitarity based observations regarding one-loop amplitudes in the theory. *
On Tuesday at 15:45 in L4, a seminar in the Algebraic Geometry series:
Evgeny Shinder (Sheffield)
Specialization of (stable) rationality
Further information: The specialization question for rationality is the following one: assume that very general fibers of a flat proper morphism are rational, does it imply that all fibers are rational? I will talk about recent solution of this question in characteristic zero due to myself and Nicaise, and Kontsevich-Tschinkel. The method relies on a construction of various specialization morphisms for the Grothendieck ring of varieties (stable rationality) and the Burnside ring of varieties (rationality), which in turn rely on the Weak Factorization and Semi-stable Reduction Theorems.
On Thursday, November 30, at 12:45 in L2, a seminar in the Strings Junior series:
Hadleigh Frost
Analytic continuation of path integrals
On Thursday, November 30, at 13:00 in Dalitz Institute, a seminar in the Dalitz Seminar in Fundamental Physics series:
Hendrik Vogel (SLAC)
TBA
On Thursday, November 30, at 16:00 in L6, a seminar in the Number Theory series:
Sam Chow (York)
A Galois counting problem
Further information: We count monic quartic polynomials with prescribed Galois group, by box height. Among other things, we obtain the order of magnitude for  quartics, and show that non-quartics are dominated by reducibles. Tools include the geometry of numbers, diophantine approximation, the invariant theory of binary forms, and the determinant method. Joint with Rainer Dietmann.
On Thursday, November 30, at 16:15 in Dennis Sciama Lecture Theatre, a seminar in the Theoretical Particle Physics series:
Ana Achucarro (Universiteit Leiden)
Multifield inflation
On Thursday, November 30, at 17:00 in L3, a seminar in the String Theory series:
Benjamin Assel (Cern)
RG flows in 3d N=4 gauge theories
Further information: I will present a new approach to study the RG flow in 3d N=4 gauge theories, based on an analysis of the Coulomb branch of vacua. The Coulomb branch is described as a complex algebraic variety and important information about the strongly coupled fixed points of the theory can be extracted from the study of its singularities. I will use this framework to study the fixed points of U(N) and Sp(N) gauge theories with fundamental matter, revealing some surprising scenarios at low amount of matter.  
On Friday, December 1, at 15:30 in Martin Wood Lecture Theatre, a seminar in the Colloquia Series Seminars series:
Prof Frederick K. Lamb (University of Illinois)
The Iran Nuclear Deal
On Friday, December 1, at 16:00 in L1, a seminar in the Math Colloquium series:
Luigi Ambrosio (Scuola Normale Superiore di Pisa)
New developments in the synthetic theory of metric measure spaces with Ricci curvature bounded from below
Further information: The theory of metric measure spaces with Ricci curvature from below is growing very quickly, both in the 'Riemannian' class RCD and the general  CD one. I will review some of the most recent results, by illustrating the key identification results and technical tools (at the level of calculus in metric measure spaces) underlying these results.  
On Monday, December 4, at 14:15 in L5, a seminar in the Geometry and Analysis series:
Nathan Dunfield (Illinois at Urbana-Champaign)
Floer homology, group orders, and taut foliations of hyperbolic 3-manifolds
Further information: A bold conjecture of Boyer-Gorden-Watson and others posit that for any irreducible rational homology 3-sphere M the following three conditions are equivalent: (1) the fundamental group of M is left-orderable, (2) M has non-minimal Heegaard Floer homology, and (3) M admits a co-orientable taut foliation. Very recently, this conjecture was established for all graph manifolds by the combined work of Boyer-Clay and Hanselman-Rasmussen-Rasmussen-Watson. I will discuss a computational survey of these properties involving half a million hyperbolic 3-manifolds, including new or at least improved techniques for computing each of these properties.  
On Tuesday, December 5, at 12:00 in L4, a seminar in the Relativity series:
Kasper Larsen (Southampton University)
Azurite: A new algorithm for finding bases of loop integrals
Further information: Scattering amplitudes computed at a fixed loop order, along with any other object computed in perturbative QFT, can be expressed as a linear combination of a finite basis of loop integrals. To compute loop amplitudes in practise, such a basis of integrals must be determined. In this talk I introduce a new algorithm for finding bases of loop integrals and discuss its implementation in the publically available package Azurite.