The Øresund Seminar - Lund 8/9, 2026

Information about the Øresund Seminar in Lund 8/9, 2026

We are happy to announce that the next Øresund Seminar will be held in the Autumn of 2026. It will this time take place in Lund, at the Centre for Mathematical Sciences at Lund University. The lectures will be in the lecture room Hörmander, just to your right when you enter the mathematics department. You can follow this link to find your way to the mathematics department, the entrance is on the east side towards sjön Sjön.

The Øresund seminar starts after a joint lunch at 12.00 on September 8th and roughly follows the schedule below.

Please register for the event one the following link before September 4th, so we can order appropriate amount of coffee and seats for dinner.

The dinner will take place at the Grand Hotel, Lund.

13.15-14.00: Théo Belin (Lund University)

Title: Validity of Amplitude Equations for Various PDEs
Abstract: Click to expand →

Abstract:

PDE systems encountered in many fields of physics and applied sciences can become quite complex. However near a constant steady state, the dynamics of these nonlinear systems can very often be effectively approximated by a small set of scalar equations called amplitude (or modulation) equations. For dissipative systems close to the onset of an instability, the Ginzubrg-Landau equation is one such amplitude equation. For dispersive systems with frequency-localized perturbations, the corresponding amplitude equation is the NLS equation. The rigorous justification of these amplitude equations can provide important information about the long-time dynamics of the original system. In this talk, we look at systems with one unbounded spatial direction and discuss new approximation results for quasilinear pattern-forming systems and for a nonlocal Klein-Gordon equation. This talk is based on two joint works with Guido Schneider and with Anna Logioti and Nils Thorin.

14.15-15.00: Diane Saint Aubin (University of Zürich)

Title: Third Order Upper Bound for the Ground State Energy of the Dilute Bose Gas
Abstract: Click to expand →

Abstract:

We derive an upper bound for the ground-state energy per unit volume of a dilute Bose gas in the thermodynamic limit which resolves the third order term predicted by Wu, Hugenholtz and Pines, and Sawada. Our result applies to radial, compactly supported potentials V ∈ L2(R3) that have positive scattering length, are stable, and do not admit two-body bound states. In particular, this includes the case V ≥ 0, and thus extends the class of potentials covered by the Lee-Huang-Yang upper bound established by Yau and Yin, as well as the one by Basti, Cenatiempo, and Schlein. The main novelty of our proof is the introduction of a cutoff that constrains the local number of excitations and permits the construction of a trial state with the correct energy density at any length scale below the thermodynamic one.

15.00-15.30 Coffee break

15.30-16.15: Jingxuan Zhang (Tsinghua University)

Title: Degenerate diffusion estimate
Abstract: Click to expand →

Abstract:

We consider degenerate non-autonomous parabolic equations in $L^p$ spaces for all $1\le p\le\infty$, and prove integrated Gaussian space-time upper bounds on their solutions. Our bounds cover both linear and nonlinear equations on general Riemannian manifolds.

16.30-17.15: Benjamin Eichinger (Lancaster University)

Title: New Universality classes associated to fractals
Abstract: Click to expand →

Abstract:

Universality describes the phenomena that the local behavior of zeros of orthogonal polynomial depends only on general characteristics of the system, rather than on its precise properties. From a modern perspective, such local behavior is analyzed through local scaling limits of the Christoffel–Darboux kernel. Recent works have established necessary and sufficient conditions for the most studied universality classes, including bulk universality and hard-edge universality. In all these settings, the rescaled Christoffel–Darboux kernel converges to a single limit kernel.

In this talk, we consider scaling limits in which there is not a single limit kernel, but rather an entire cycle of limit kernels. We show that this type of behavior arises naturally when studying scaling limits for orthogonal polynomials associated with the equilibrium measure of the real Julia set of an expanding polynomial or with the Cantor measure on the classical middle-third Cantor set.

This talk is based on joint work with Alexander Kheifets, Milivoje Lukić and Peter Yuditskii.

18.30 Dinner at Grand Hotel

Current organizers and contact:

U Copenhagen:

Søren Fournais

Niels Martin Møller

Jan Philip Solovej

Lund U:

Magnus Goffeng [magnus dot goffeng (at) math dot lth dot se (responsible for the homepage)]

Jacob Stordal Christiansen

Erik Wahlén

Information about the Øresund Seminar in Lund 8/9, 2026

13.15-14.00: Théo Belin (Lund University)

Title: Validity of Amplitude Equations for Various PDEsAbstract: Click to expand →

Abstract:

14.15-15.00: Diane Saint Aubin (University of Zürich)

Title: Third Order Upper Bound for the Ground State Energy of the Dilute Bose GasAbstract: Click to expand →

Abstract:

15.00-15.30 Coffee break

15.30-16.15: Jingxuan Zhang (Tsinghua University)

Title: Degenerate diffusion estimateAbstract: Click to expand →

Abstract:

16.30-17.15: Benjamin Eichinger (Lancaster University)

Title: New Universality classes associated to fractalsAbstract: Click to expand →

Abstract:

18.30 Dinner at Grand Hotel

Current organizers and contact:

U Copenhagen:

Lund U:

Title: Validity of Amplitude Equations for Various PDEs
Abstract: Click to expand →

Title: Third Order Upper Bound for the Ground State Energy of the Dilute Bose Gas
Abstract: Click to expand →

Title: Degenerate diffusion estimate
Abstract: Click to expand →

Title: New Universality classes associated to fractals
Abstract: Click to expand →