Thu, 18 Feb 2016
12:00
L6

Time-Periodic Einstein-Klein-Gordon Bifurcations Of Kerr

Yakov Shlapentokh-Rothman
(Princeton University)
Abstract

For a positive measure set of Klein-Gordon masses mu^2 > 0, we construct one-parameter families of solutions to the Einstein-Klein-Gordon equations bifurcating off the Kerr solution such that the underlying family of spacetimes are each an asymptotically flat, stationary, axisymmetric, black hole spacetime, and such that the corresponding scalar fields are non-zero and time-periodic. An immediate corollary is that for these Klein-Gordon masses, the Kerr family is not asymptotically stable as a solution to the Einstein-Klein-Gordon equations. This is joint work with Otis Chodosh.

 
Thu, 11 Feb 2016
12:00
L6

Blow up by bubbling in critical parabolic problems

Manuel del Pino
(Universidad de Chile)
Abstract
We report some new results on construction of blowing up solutions by scalings of a finite energy entire steady states in two parabolic equations: the semilinear heat equation with critical nonlinearity and the 2d harmonic map flow into S2.
Thu, 28 Jan 2016
12:00
L6

Meaning of infinities in singular SPDEs

Wei-Jun Xu
(Warwick University)
Abstract
Many interesting stochastic PDEs arising from statistical physics are ill-posed in the sense that they involve products between distributions. Hence, the solutions to these equations are obtained after suitable renormalisations, which typically changes the original equation by a quantity that is infinity. In this talk, I will use KPZ and Phi^4_3 equations as two examples to explain the physical meanings of these infinities. As a consequence, we will see how these two equations, interpreted after suitable renormalisations, arise naturally as universal limits for two distinct classes of statistical physics systems. Part of the talk based on joint work with Martin Hairer.
Thu, 10 Mar 2016

16:00 - 17:00
L5

On the number of nodal domains of toral eigenfunctions

Igor Wigman
(King's College London)
Abstract

We study the number of nodal domains of toral Laplace eigenfunctions. Following Nazarov-Sodin's results for random fields and Bourgain's de-randomisation procedure we establish a precise asymptotic result for "generic" eigenfunctions. Our main results in particular imply an optimal lower bound for the number of nodal domains of generic toral eigenfunctions.

Thu, 03 Mar 2016

16:00 - 17:00
L2

Hecke eigenvalue congruences and experiments with degree-8 L-functions

Neil Dummigan
(University of Sheffield)
Abstract

I will describe how the moduli of various congruences between Hecke eigenvalues of automorphic forms ought to show up in ratios of critical values of $\text{GSP}_2 \times \text{GL}_2$ L-functions. To test this experimentally requires the full force of Farmer and Ryan's technique for approximating L-values given few coefficients in the Dirichlet series.

Thu, 25 Feb 2016

16:00 - 17:00
L2

Badly approximable points

Victor Beresnevich
(University of York)
Abstract

I will discuss the notion of badly approximable points and recent progress and problems in this area, including Schmidt's conjecture, badly approximable points on manifolds and real numbers badly approximable by algebraic numbers.

Thu, 28 Jan 2016

16:00 - 17:00
L5

Iwasawa theory for the symmetric square of a modular form

David Loeffler
(University of Warwick)
Abstract

Iwasawa theory is a powerful technique for relating the behaviour of arithmetic objects to the special values of L-functions. Iwasawa originally developed this theory in order to study the class groups of number fields, but it has since been generalised to many other settings. In this talk, I will discuss some new results in the Iwasawa theory of the symmetric square of a modular form. This is a joint project with Sarah Zerbes, and the main tool in this work is the Euler system of Beilinson-Flach elements, constructed in our earlier works with Kings and Lei.

Thu, 21 Jan 2016

16:00 - 17:00
L5

Height of rational points on elliptic curves in families

Pierre Le Boudec
(EPFL (Ecole Polytechnique Federale de Lausanne))
Abstract

Given a family $F$ of elliptic curves defined over $Q$, we are interested in the set $H(Y)$ of curves $E$ in $F$, of positive rank, and for which the minimum of the canonical heights of non-torsion rational points on $E$ is bounded by some parameter $Y$. When one can show that this set is finite, it is natural to investigate statistical properties of arithmetic objects attached to elliptic curves in the set $H(Y)$. We will describe some problems related to this, and will state some results in the case of families of quadratic twists of a fixed elliptic curve.

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