# This Week

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

On Monday, May 21, at 12:45 in L3, a seminar in the String Theory series:
Sunil Mukhi (IISER Pune)
Exotic Rational Conformal Field Theories and the Modular Bootstrap
Further information: I will summarise old and recent developments on the classification and solution of Rational Conformal Field Theories in 2 dimensions using the method of Modular Differential Equations. Novel and exotic theories are found with small numbers of characters and simple fusion rules, one of these being the Baby Monster CFT. Correlation functions for many of these theories can be computed using crossing-symmetric differential equations.
On Monday, May 21, at 14:00 in Dennis Sciama Lecture Theatre, a seminar in the Astrophysics Colloquia series:
James Allison (Sydney)
TBD (galaxy evolution)
On Monday, May 21, at 14:15 in L4, a seminar in the Geometry and Analysis series:
Momchil Konstantinov (UCL)
Higher rank local systems and topology of monotone Lagrangians in projective space
Further information: Lagrangian Floer cohomology can be enriched by using local coefficients to record some homotopy data about the boundaries of the holomorphic disks counted by the theory. In this talk I will explain how one can do this under the monotonicity assumption and when the Lagrangians are equipped with local systems of rank higher than one. The presence of holomorphic discs of Maslov index 2 poses a potential obstruction to such an extension. However, for an appropriate choice of local systems the obstruction might vanish and, if not, one can always restrict to some natural unobstructed subcomplexes. I will showcase these constructions with some explicit calculations for the Chiang Lagrangian in CP^3 showing that it cannot be disjoined from RP^3 by a Hamiltonian isotopy, answering a question of Evans-Lekili. Time permitting, I will also discuss some work-in-progress on the topology of monotone Lagrangians in CP^3, part of which follows from more general joint work with Jack Smith on the topology of monotone Lagrangians of maximal Maslov number in projective spaces.
On Monday, May 21, at 16:15 in Beecroft Seminar Room, a seminar in the Theoretical Particle Physics series:
Jure Zupan (University of Cincinnati)
Taming dark matter interactions with matter
On Tuesday at 11:30 in TBC, a seminar in the Cosmology series:
Ludovic Van Waerbeke (University of British Columbia)
TBC
On Tuesday at 12:00 in L4, a seminar in the Quantum Field Theory series:
Christian Saemann (Heriot Watt University)
Towards an M5-brane model: A 6d superconformal field theory
Further information: I will discuss a classical six-dimensional superconformal field theory containing a non-abelian tensor multiplet which we recently constructed in arXiv:1712.06623. This theory satisfies many of the properties of the mysterious (2,0)-theory: non-abelian 2-form potentials, ADE-type gauge structure, reduction to Yang-Mills theory and reduction to M2-brane models. There are still some crucial differences to the (2,0)-theory, but our action seems to be a key stepping stone towards a potential classical formulation of the (2,0)-theory. I will review in detail the underlying mathematics of categorified gauge algebras and categorified connections, which make our constructions possible.
On Tuesday at 15:45 in L4, a seminar in the Algebraic Geometry series:
Navid Nabijou (Imperial College London)
A Recursive Formula for Log Gromov-Witten Invariants
Further information: Given a smooth variety X containing a smooth divisor Y, the relative Gromov-Witten invariants of (X,Y) are defined as certain counts of algebraic curves in X with specified orders of tangency to Y. Their intrinsic interest aside, they are an important part of any Gromov-Witten theorist’s toolkit, thanks to their role in the celebrated “degeneration formula.” In recent years these invariants have been significantly generalised, using techniques in logarithmic geometry. The resulting “log Gromov-Witten invariants” are defined for a large class of targets, and in particular give a rigorous definition of relative invariants for (X,D) where D is a normal crossings divisor. Besides being more general, these numbers are  intimately related to constructions in Mirror Symmetry, via the Gross-Siebert program. In this talk, we will describe a recursive formula for computing the invariants of (X,D) in genus zero. The result relies on a comparison theorem which expresses the log Gromov-Witten invariants as classical (i.e. non log-geometric) objects.
On Thursday at 12:45 in L6, a seminar in the Strings Junior series:
Sebastjan Cizels
Further information: We will briefly revisit Voronoi summation in its classical form and mention some of its many applications in number theory. We will then show how to use the global Whittaker model to create Voronoi type formulae. This new approach allows for a wide range of weights and twists. In the end we give some applications to the subconvexity problem of degree two $L$-functions.