Research in Theoretical Hadronic Physics and Related Topics

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Nuclear Physics is the field of physics that studies the atomic nucleus constituents (protons and neutrons) and the interactions that hold them together. In this context, this project will investigate a number of fundamental topics of interest in nuclear theory. Specifically, the project will focus on providing a better understanding of the proton structure. One of the outstanding problems is the proton charge radius puzzle, triggered by the fact that measurements using electrons and muons give rise to different values of the proton charge radius. Seeking a resolution to this puzzle, the PI and his collaborators will calculate crucial corrections needed to understand experiments performed at the Thomas Jefferson National Accelerator Facility (JLab) (USA) and experiments proposed at JParc (Japan). The PI will involve undergraduate students in these projects, and continue fostering research connections between universities and national labs (especially W&M and JLab).This project will study nuclear structure-dependent corrections to the Lamb shift in muonic He-4, supporting the extension to He-4 of the muonic hydrogen Lamb shift measurements which led to the proton radius puzzle. This project will also study models for light mass muon specific new particles, seeking a model that would encompass the constraints on such particles, pursuing first models inspired by suggestions of Froggatt and Nielsen. Regarding pion form factors, they are measured in the reaction e+ p - e pi n, with an extrapolation to the pion pole, and a background from non-pole terms that must be modeled. Given that the related pi + p - (lepton pair) + n process is anticipated at JParc, the PI and his collaborators will make numerically clear the relevant backgrounds. The PI will also study twisted photons, which have structured wave fronts that allow high angular momentum (many h-bar) in the direction of motion, and which can be produced at hadron scale energies.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.