Jean-François Fortin

Assistant professor
Département de physique, de génie physique et d'optique
Université Laval
Québec, QC G1V 0A6, Canada
+1 418 656-2131 x2023
jean-francois.fortin@phy.ulaval.ca

I am a professor in theoretical physics at Laval University. I work on several aspects of modern theoretical physics including: particle physics; high-energy physics; quantum, conformal, supersymmetric and superconformal field theories; beyond-the-standard-model physics; phenomenology; renormalization; supersymmetry; supersymmetry breaking; dark matter; particle astrophysics; cosmology; and string theory.

The theoretical physics group meets once per week to discuss recent discoveries in related fields of interest. All students in physics and physics engineering who are interested in theoretical physics are invited to participate. For more details, do not hesitate to contact me.

Education

  1. 1999-2003: Baccalaureate in physics engineering at Laval University
  2. 2003-2004: Master in physics at Laval University
  3. 2004-2009: Doctorate in physics at Rutgers University
  4. 2009-2012: Post-doctorate in physics at UCSD
  5. 2012-2014: Post-doctorate in physics at CERN and Stanford University
  6. 2014-20??: Professor in physics at Laval University

Research

My current research interests focus on the study of theories which describe fundamental physical phenomena.

Quantum field theory
Theories originating from the union of quantum mechanics and special relativity are quantum field theories. Quantum field theories allow to describe the vast majority of the phenomena associated to the realm of elementary particles. The electromagnetic force, the weak nuclear force and the strong nuclear force are described by quantum gauge theories. The standard model of particles contains these three forces as well as the elementary particles of matter (fermions) and the Higgs boson. Quantum electrodynamics, the first example of a quantum field theory, is extremely well understood theoretically, with an extraordinary agreement between theory and measurements (more than six significant figures).

One surprising consequence of quantum field theory is the existence of the renormalization group. For a quantum field theory, coupling constants are not really constant, they rather change depending on the energy used to probe the theory. Hence, in quantum electrodynamics, the fine structure constant is not fixed, it changes when the energy of the incident particle increases. This change leads to the renormalization group.
Conformal field theory
Limit cycles and fixed points of the renormalization group flow correspond to quantum field theories with extra spacetime symmetries: scale invariance for limit cycles and conformal invariance (which include scale invariance) for fixed points. It is however possible to show that limit cycles do not exist in the weak-coupling limit. Since conformal field theories, which represent renormalization group flow fixed points, have a rich structure that allows to obtain more information on the theory for all coupling strength, it is of the utmost importance to study them in more details. For conformal field theories, the ultimate goal would be to classify them, in a way reminiscent to the classification of Lie algebras.
Supersymmetry
One problem encountered in the standard model of particles is related to the stability of the electroweak scale. Indeed, in quantum field theory, quantum corrections can destabilize an energy scale and push it up to the highest physically acceptable energy (which usually is the Planck scale). Since electroweak symmetry breaking occurs around 100 GeV and the Planck scale is of the order of 1018 GeV, there should exist new particles around the electroweak scale to solve this problem.

Supersymmetry postulates that every known particle has a superpartner, and these superpartners can alleviate the hierarchy problem mentionned above. Studying the structure of supersymmetric theories and supersymmetry breaking could help answering several questions posed by the standard model of particles.
Dark matter
The origin of dark matter, which explains the speeds of stars in galaxies and of galaxies in galaxy clusters, is still unknown. Supersymmetry could naturally introduce a new massive particle without electric charge that could play the role of dark matter. There are several other possibilities to explain dark matter, however it has still eluded experimental observations here on Earth.

Publications

Most of the articles in theoretical physics are available on the arXiv or on inspire. My publications can be consulted directly on the arXiv and the relevant statistics (number of papers, number of citations, etc.) can be found on inspire.

Students and researchers

Here is a list of students and postdocs who collaborated with me on several projects in theoretical physics.

Useful links