Electromagnetic Probes for Precise Imaging of Hadrons

About This Grant

The Thomas Jefferson National Accelerator Facility (JLab) currently operating and the Electron-Ion Collider (EIC) under construction at Brookhaven National Laboratory (BNL) are recognized worldwide as premier laboratories for nuclear science. By analyzing high-energy collisions of electrons and nuclei, these research facilities provide access to a new frontier in nuclear physics, ensuring US leadership in both nuclear science and accelerator physics and technology. This project aims at theoretical studies of electromagnetic radiation effects taking place during electron-nucleus collisions. By employing advanced models of electron-nuclear collisions, the PI and his collaborators will develop new methodology for relating the energy and momenta of collision products to intrinsic properties of fundamental building blocks of matter, namely, quarks and hadrons. Results of the project will provide scientific guidance for new experiments at EIC and TJNAF. In addition, the project supports an educational component, contributing to training of nuclear workforce in US. This project aims at developing theoretical approaches for the analysis of electron-nucleus and electron-proton collisions to be studied at the Electron Ion Collider (EIC) at the Brookhaven National Laboratory (BNL) and at the Thomas Jefferson National Accelerator Facility (JLab). This project will advance the current understanding of electromagnetic interactions of hadrons beyond the leading order in Quantum Electrodynamics (QED) by developing new theoretical and modeling approaches. Current and forthcoming experimental programs in hadronic physics achieve unprecedented precision aiming to provide 3D imaging of hadronic structure. However, interpretation of the measurements in terms of hadronic structure parameters – such as Generalized Parton Distributions (GPD) and Transverse Momentum Dependent Parton Distributions (TMD) - can be limited due to higher-order electromagnetic QED effects. The main challenge in evaluating these effects is that relevant calculations require knowledge of hadronic structure. This project will provide a systematic analysis of structure-dependent high-order QED corrections for scattering of electrons and positrons on nuclei and nucleons. The PI and his collaborators will focus on lepton-scattering reactions leading to single-spin asymmetries and charge asymmetries that are otherwise zero in the leading order of QED. The team will analyze the theory-experiment discrepancy of the measured transverse beam asymmetry on 208Pb at TJNAF; underlying physics mechanisms for a large observed transverse target spin asymmetry due to two-photon exchange in inclusive deep-inelastic scattering (DIS) and their implications for analyses of spin effects in semi-inclusive DIS; and high-order QED effects in the measurements of deep-exclusive processes on hadrons. The new approaches and computer codes will be made available to the hadronic physics community for the purposes of experimental data analysis. 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.