Le 19 juin 2026, Abedennour (Hakim) Dib a brillamment défendu sa thèse intitulée « Théories maxwelliennes généralisées – structure théorique et tests expérimentaux ». Bravo Hakim !
Résumé de la thèse :
Astrophysical observations are mainly based on electromagnetic signals, still read with 19th century Maxwell’s theory, linear and without photonic mass, possibly approximating a larger theory, such as Newtonian gravity for general relativity. We
examine Generalised Maxwellian Theories (GMT) that induce A) modifications of Maxwell’s laws testable using solar wind
spacecraft data; B) birefringence, object of experiments in France, for which the refractive index depends on light
polarisation and propagation direction; C) dispersion for which the group velocity differs from c by a factor proportional to
the inverse of the square of the frequency, impacting pulsar signals, Fast Radio Bursts (FRBs), multi-messenger astronomy
and graviton mass estimates; D) a frequency shift in the vacuum, due to the energy exchange between the photon and
background fields, causing the reinterpretation of the universe expansion and of dark energy. Going beyond Maxwell is a
necessity in quantum electrodynamics for taking into account non-linear corrections. GMT are either massive (de Broglie-
Proca, Bopp, Podolski, Stueckelberg and others) or non-linear (Born-Infeld, von Heisenberg-Euler and others). In modern
particle physics, the Standard Model (SM), which respects Lorentz-Poincaré symmetry, does not explain the oscillations
and masses of neutrinos, the matter-antimatter unbalance, and the dark universe. For the SM, the photon is the only free
massless particle. Theories extending the SM based on symmetry breaking (SME theories) lead to an effective, gauge
invariant, but anisotropic photon mass. In this thesis, we picked some of our publications and discussed the non-linear
effects induced by background fields on the free photon propagation, highlighting the presence of frequency shifts. Within
the same class of models, we present the mechanisms that lead to the emergence of an effective mass due to the photon-
background interactions, as well as the stability and propagation features of such massive extensions. We notably show
the presence of a transversal mass that preserves gauge invariance as well as the absence of tachyons in the studied
cases.
Composition du jury :
Rapporteurs :
Robertus POTTING, Professeur, Universidade do Algarve
Nikolaos E MAVROMATOS, Professor, Ethnikó Metsóvio Polytechneío NTUA – CERN – King’s College
Examinateurs :
Jan-Willem VAN HOLTEN, Emeritus professor of Theoretical Physics, Universiteit Leiden – NIKHEF
Salvatore CAPOZZIELLO, Professor, Università degli Studi di Napoli Federico II – SSM
Sébastien CELESTIN, Professeur des universités, Université d’Orléans
Claus LAMMERZAHL, Professeur émérite, Universität Bremen
José A HELAYEL-NETO, Professor, Centro Basileiro de Pesquisas Físicas CBPF
Invité :
Tomislav PROKOPEC, Universiteit Utrecht
Directeurs de thèse :
Alessandro SPALLICCI, Professeur émérite, Université d’Orléans