Hadronic QCD Physics

We are:

along with postdoctoral researchers and graduate students.

Our research explained for the public:

The aim of our research group is to study and understand certain aspects of the inner workings of the fundamental building blocks of matter (quarks). Quarks are not manifested as free particles in nature, therefore their study involves investigations of their stable combinations in particles, such as nucleons (protons and neutrons) as well as the particles which ``transmit'' the nuclear force among them, the mesons. Ultimately, the glue itself, which binds quarks, is also an objective of our investigations. In order to accomplish this goal, our group leads experimental efforts in the field of subatomic physics.

Nucleons and mesons, then, are composed of smaller, more fundamental particles, the quarks and gluons. As a result of the motion of the quarks (which produces magnetism) and their electrical charge, nucleons and mesons exhibit a distinct structure. We plan to map out this structure accurately, in order to test theoretical predictions and to provide valuable input to the interpretation of other experiments in the field. We have chosen the high energy electron beam at the Jefferson Lab, USA, for this mapping, because electrons do not have a composite structure of their own and are thus the cleanest probe to access the desired physics.

The nature of the interaction among quarks, on the other hand, is best investigated with photons (quanta of pure energy) through the production of exotic mesons which are not found in ordinary matter. These exotic mesons, called exotic hybrid mesons, carry unique signatures of the combinations of quarks and gluons. The investigation of exotic particles will be pursued at the proposed, new Hall D/GlueX facility at Jefferson Lab, which will take advantage of the future energy upgrade at this laboratory.

Our main endeavours are presented below.

• The GlueX and JEF Experiments

  For the past quarter-century, physicists have suspected that subatomic particles made of the very glue that holds matter together at the most fundamental level must exist. Recently, searches for these elusive particles have intensified as tantalizing hints of their presence have appeared. These include evidence for exotics (mesons with exotic quantum number combinations). The GlueX project at Jefferson Lab aims to identify these unusual particles predicted by QCD, but whose structure lies outside the quark model. The JLab Eta Factory (JEF) experiment will involve precision measurements of eta rare de-cays, using an upgraded FCAL calorimeter. The eta decay photons and leptons will be measured with a high- granularity, high-resolution PbWO4 crystal core in the central FCAL-II region, which minimizes shower overlaps and optimizes the energy and position resolutions. Access to eta decays provides a rich flavor-conserving laboratory for new physics beyond the Standard Model (SM): JEF will facilitate the search for gauge boson candidates in the sub-GeV mass range, probing highly motivated portals coupling the SM to the dark sector.  JEF will also test fundamental symmetries and the quark mass ratio, among others.

• Studies of Hadronic Structure with Electromagnetic Probes

  It is widely accepted that nucleons and nuclei are built from quarks, and the theory which describes their behavior is QCD, but this understanding is far from perfect and still untested in many ways. Our research program at Jefferson Lab (USA) is based on the search of direct QCD signatures in mesons and nucleons below the region of perturbative QCD (pQCD). For example, pQCD predicts a unique behavior of the pion form factor, as a direct consequence of the asymptotic freedom of quarks at infinite momenta. Our experiments will be the first to test this prediction.

• Nuclear Imaging of Plants

  An exciting addition to our research program is the development of nuclear imaging detectors dedicated to plant imaging, which will be used to study plants at a molecular level to improve the understanding of plant productivity; nutrient and water use efficiency; plant-microbe interactions; and their responses to environmental stress and injury.

• Studies of Hadronic Structure with the Electron Ion Collider

  The Electron-Ion Collider (EIC) is a premier project in nuclear physics, under design and soon construction with plans of it coming online in the early 2030s. It aims to study the dynamic interactions of the smallest internal building blocks of visible matter, quarks and gluons, and help us understand the underlying laws that govern the strongest force in nature. Our group has been active in the EIC project for several years, including participation in its design (Yellow) report and by running innovative AI/machine learning methods towards optimizing the particle tracking design in one of its early consortia (ECCE). We are part of EIC Canada. Based on our expertise in designing and building the Barrel Calorimeter for GlueX, we have undertaken a central role in the design and construction of the Barrel Imaging Calorimeter (BIC) together with groups in the USA, Germany and Korea. 

For the experts:

• We are a leading group in the GlueX Project.
• We have co-spokesmanhip in the JEF Experiment.
• We have co-spokesmanship in the Pion Form Factor program at Jefferson Lab.
• We play a leading role in the Electron-Ion Collider.