Centre de Physique Théorique


April 2019

Friday 5 April 14:00-15:00, Amphi 5

Differential calculus for Jordan algebras and modules and the Standard model of particle physics

Alessandro Carotenuto (SISSA)

In this talk I will review some recent developments in the differential calculus for Jordan algebras and the theory of connections for Jordan modules. Jordan algebras were introduced last century as algebraic framework to describe quantum systems and the reasons to give an explicit characterization of their differential calculus originated from the suggestion of Michel Dubois-Violette that the existence of three generations of particles in the Standard Model might be explained by allowing for the exceptional Jordan algebra $J^8_3$ as algebra of quantum observables.

Wednesday 10 April 14:00-15:00, Frumam

Théorie de la diffusion pour des modèles mathématiques de l’interaction faible

Benjamin Alvarez (Université de Lorraine)


La désintégration du boson W en leptons est modélisée par un opérateur non borné auto-adjoint appelé Hamiltonien qui agit sur un espace d’Hilbert, construit comme un produit tensoriel d’espaces de Fock. Les valeurs que peut prendre l’énergie de ce système sont inclues dans le spectre de cet opérateur. L’espace d’Hilbert associé au spectre absolument continue modélise l’ensemble des particules qui se propagent à l’infini et que l’on appelle particules diffusées. On s’attend à ce que de tels états se comportent asymptotiquement comme des états libres, c’est-à-dire, soumis à aucune interaction. Cette intuition peut être décrite mathématiquement par une formule que l’on appelle complétude asymptotique. Par ailleurs, une expérience en théorie des particules consiste à détecter les particules diffusées après interaction tout en connaissant le ou les états diffusés initiaux. Il est donc naturel d’introduire un opérateur permettant de construire les états sortant à partir des états entrant que l’on appelle matrice de diffusion. L’objectif d’une théorie de la diffusion est de démontrer l’existence de cet objet ainsi que la complétude asymptotique. Dans cette présentation nous étudierons l’exemple de la désintégration du boson d’interaction W dans le cas où les leptons sont considérés comme des particules massives ainsi que dans le cas, plus difficile, où les neutrinos sont considérés comme n’ayant pas de masse.

Thursday 11 April 14:00-15:00, Amphi 5 du CPT

Testing the equivalence principle on cosmic scales

Pierre Fleury (University of Geneva)

The equivalence principle is the main pillar of relativistic gravitation. Albeit exquisitely constrained on Earth and in the Solar System, its validity remains to be proved on cosmic scales, especially when the unknown dark matter is concerned. In this talk, I will show that relativistic effects in galaxy surveys offer the possibility to directly test the equivalence principle. Ten-percent level constraints on its deviations are achievable with future surveys like the Square Kilometer Array.

Friday 12 April 14:00-15:00, Amphi 5

Composite Higgs and lattice field theory

Luigi Del Debbio (University of Edinburg)

Composite Higgs models describe physics beyond the Standard Model in terms of new strongly-interacting sectors. Lattice field theory provides the tools to study the dynamics of such sectors from first principles if a UV completion of the model exists. On one hand viable UV completions must be compatible with the constraints coming from experimental data, while on the other hand having a UV completion has very stringent consequences for the dynamics. Recent lattice studies have investigated a variety of theories trying to characterise their properties, and understand the potential phenomenological implications. I will review a number of examples, and discuss potential future directions.

Wednesday 17 April 14:00-15:00, CPT, Amphi 5

N-body self-consistent hamitonian approach for the wave-particle interaction in periodic structures and the Abraham-Minkowski dilemma in plasmas and waveguides

Damien Minenna (PIIM, Marseille)


The presentation is divided in two parts:
(i) We model the momentum exchange in nonlinear wave-particle interaction using an N-body self-consistent Hamiltonian description. To drastically reduce the number of degrees of freedom, we use a discrete model allowing us to accurately study periodic structures, such as free electron lasers, gyrotrons or particle accelerators. From our model, we constructed an one-dimension time domain symplectic algorithm to simulate to metallic waveguides of traveling-wave tubes (TWTs). This algorithm is able to simulate arbitrary waveform (not just field envelope), including continuous waveform (CW), multiple carriers or digital modulations (telecom signals) and was validated against measurements.

(ii) Whenever light is slowed down, for any cause, two different formulas give its momentum (one kinematic and one canonical). For dielectrics, the coexistence of those momenta was the heart of the century-old Abraham-Minkowski dilemma, recently resolved. We demonstrate that this framework extends to momentum exchange in wave-particle interaction; in particular to vacuum waveguides of electron tubes (metallic slow-wave structures). We also raise evidences that the dilemma occurs within the Landau damping (or amplification) context in plasmas.

- D. F. G. Minenna, et al., Europhys. Lett., 122, 44002 (2018).
- D. F. G. Minenna, et al., arXiv: 1902.06431

Friday 19 April 14:00-15:00, CPT, Amphi 5

Refraction and Reflexion According to The Principle of General Covariance

Patrick IGLESIAS (Institut de Mathématiques de Marseille I2M)

I will show how the principle of general covariance, introduced by Souriau in smoothly uniform contexts, can be extended to singular situations where the metric is discontinuous along a hypersurface. I will show then how to recover the principle of refraction of geodesics, in particular, by determining the Underdetermined differential system thanks to symplectic scattering.

Wednesday 24 April 14:00-15:30, Amphi 5

Honeycombs, polytopes, and orbital measures: another look at representation theory

Robert Coquereaux (CPT)

After introducing several geometrical models that can be used to calculate multiplicities in Lie group theory we describe associated polytopes whose volumes can be considered as semi-classical approximations of those multiplicities.

From 29 to 30 April, Marseille, Luminy

Bose-Einstein Condensation in Inorganic and Organic Matter

The scientific aim of this Colloquium is to bring together researchers - experimenters and theoreticians - to discuss about
coherent long-range dynamic phenomena and long-lived collective and quasi-particle modes in inorganic and organic matter.
The scientific debate will focus on equilibrium and non-equilibrium transitional phenomena observed and modelled in quantum and
classical systems relevant to biophysics and condensed matter.