Prof. Frank WILCZEK Prix Nobel de Physique 2004

Le 14 avril à 18h, salle Dussane
Conférence généraliste
The Universe is a Strange Place

Présentation : Edouard Brezin.

Over the course of the twentieth century we have constructed a very
successful fundamental theory of the behavior of matter. Viewed from
this perspective, the world looks very different from our everyday
reality. It is a very strange place, and a beautiful one — in
particular, we’ve come to understand that the building blocks of
matter appear as notes in a Music of the Void. I’ll describe this
using a combination of facts, pictures, and jokes. Finally I’ll
discuss some recent discoveries indicating that the world is even
stranger than we’ve understood so far, and how we’re rising to the

17 avril à 13h30, salle Dussane
Conférence spécialisée, Séminaire du département de physique.
QCD Meets BCS Meets QQ

What happens to matter when you squeeze it very, very hard ? A child
might ask this question, as might a neutron star astrophysicist or a
quantum field theorist looking for challenges. By adapting the
methods of superconductivity theory (BCS) to the fundamental theory
of matter (QCD) we get some beautiful and surprising answers. (For
experts : We find both confinement and chiral symmetry breaking in a
controlled, weak-coupling approximation.) The nature of quark-quark
(QQ) interactions play a crucial role in the analysis, which
motivates some new phenomenology leading to a dramatic prediction.

18 avril à 14h, Département de physique salle D5
3ème Conférence spécialisée.
Engineering the Dirac Equation

The Dirac equation occurs naturally in the relativistic theory of
elementary particles, but for both practical and theoretical reasons
it’s very interesting to consider approximate realizations in
discrete (lattice) systems. The Dirac equation arises in, and has
important implications for, the description of low-energy excitations
in graphene and possibly other materials, as I’ll describe. Then
I’ll discuss "fermion doubling", a fundamental issue in the treatment
of chiral theories using lattice discretization. I’ll define the
problem, show its deep origins in topology, and suggest simple ways
to minimize and possibly overcome it.