3D Structure of Hadrons from Electromagnetic Probes Beyond the Leading Order of QED

George Washington University, Washington DC

Investigators

Abstract

Key questions being addressed in modern nuclear science include, among others, (i) the role of the quarks and gluons in forming nucleons (protons and neutrons) and nuclei and (ii) fundamental symmetries governing interactions between leptons (electrons and muons) and nucleons and nuclei. The US has made significant investments into fundamental science and provided facilities for nuclear research that are aimed toward finding answers to these questions. These facilities include CEBAF at the Thomas Jefferson National Accelerator Facility, which will investigate the structure of hadrons, the set of heavy elementary particles that includes the proton and neutron, and a future Electron-Ion Collider planned at Brookhaven National Laboratory. The electrons used to probe the nuclear structure are charged particles, and while scattering off nuclear targets they inevitably emit photons or exchange extra virtual photons, presenting a challenge in interpretation in terms of hadronic structure and dynamics. This project aims to develop a unified approach that will consider both high-order electromagnetic effects and the nucleon’s structure in a theoretical description of electron scattering processes. In addition, the PI will mentor students engaged in this research, provide public lectures, and organize meeting with students in local high schools in Washington, DC. This project will advance current understanding of electromagnetic interactions of hadrons beyond the leading order in QED by developing appropriate theoretical and modelling approaches. Novel effects will be considered for elastic electron-nucleon scattering, deep-virtual electroproduction of pions, semi-inclusive deep-inelastic scattering of leptons, along with new topological states of relativistic electrons. The results of the investigation will be discussed in relation to the physics programs at Jefferson Lab and future Electron-Ion Collider at Brookhaven National Lab that aim to map 3D-structure of hadrons from precision electron scattering. Results of the project will be disseminated through a user-friendly interface mirrored at Jefferson Lab (Radiative Corrections Helpdesk) to assist nuclear physics community in developing proper physics analysis tools. Novel solutions for polarization-dependent cross sections of lepton scattering will be implemented in GEANT4 toolkit through PI’s active membership in GEANT4 Collaboration. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.