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Marie Boër

Assistant Professor of Physics

Experimental Hadronic Physics, Nuclear Physics


PArtonic Structure of the HAdrons Group

Hadronic Physics is a field between particle physics and high-energy nuclear physics. It focuses on the study of the internal structure of particles, generically called Hadrons, which are composed of elementary particles, called quarks and gluons. One of our interest is to understand the properties of the hadrons from the quarks and the gluons, i.e. the internal building blocks. Quarks and gluons are considered to be the smallest "ingredient of matter" and are refered to as Partons.
Nucleons (protons and neutrons) are some of the most well-known hadrons. They are made of 3 "valence" quarks, which nature makes up the difference between the proton and the neutron (combination of quarks "up" and quarks "down"). However, the structure of the nucleon, such as any other hadron, is much more complex. The quarks interact with gluons, the particle carrying the strong force, and these gluons can split into more gluons and into pairs of quark and antiquark. At the subatomic level, we can't talk anymore in terms of "number of partons" in the nucleon, but rather of densities. The partonic density, or density in gluons, and densities in different kind of quarks, varies as a function of many parameters. For instance, the energy-momentum of the probe ("our zoom") allows to be more or less sensitive to these substructure, thus the densities are evolving as we vary the kinematic parameters of the probe and of the decay products we are looking at in a reaction. Furthermore, we have to consider this structure as having a complex dynamic, reflected in the momentum distributions of the partons, their correlations, their spin, and other properties.
Some questions scientists are addressing in Hadronic Physics are the understanding of parton distributions (1 dimension towards n-dimensions), why partons are confined in the nucleon, how the spin of a hadron is partitioned among its constituents... The theory behind these studies is called Quantum Chromodynamic (QCD), the theory of strong interaction. In QCD, the gluons are coupling with other gluons and quarks and are the careers of the "strong force", which is one of the 4 fundamental forces in physics.
We can access to the parton distributions and dynamics through medium/high energy scattering experiments. 
In the PaSHa group (PArtonic Structure of the Hadrons) group, we are specialized in studying the partonic structure of protons and neutrons, with a particular interest for moving towards multidimensional imaging. One of our speciality is the study of Generalized Parton Distributions (GPDs), which are functions accessing the transverse position of the partons versus their longitudinal momentum. This can be interpreted as "slicing" the nucleon into slices containing more and more gluons, or being closer to the core "valence quarks", these kind of pictures are usually refered to as "tomography", or can be compared in doing the MRI of the nucleon.
Our activities range from conducting experiments to phenomenology, and we are active in studying new reactions, interpreting data, analyzing data, participating in running experiments, developing new experiments, and developing new detectors. We collaborate with experimentalists and theorists around the world. In particular, we are conducting experiments at Jefferson Lab., located in Newport News, VA. This experimental facility has an accelarator providing a high intensity 11 GeV electron beam. We also have activities related to the future Electron Ion Collider (EIC), which will be built at Brookhaven National Lab (NY) in a near future.
Historical representation of a nucleon with 3 constituent quarks (left) where arrows indicate the orientation of the nucleon and quark spins; and more complex representation (right) including gluons (yellow curls), quark-antiquark pairs...

Group members


For any request, contact: mboer - at -

Research Activities

  • Generalized Parton Distributions
  • Hard Exclusive Reactions
  • Compton-like processes and di-leptons
  • Hard exclusive production of Vector Mesons
  • Exclusive production of quarkonias
  •  Jefferson Lab Hall C experiments
  • Jefferson Lab Hall A experiments
  • EIC
  • Phenomenology
  • Event generators
  • Muon detectors
Recent Publications
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