Probing Subatomic Physics Via Lepton Interactions

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Abstract for NSF Proposal Number 0555510TITLE: Probing Subatomic Physics via Lepton InteractionsProposal PIs: Dr. M. Ioana Niculescu, Dr. Kevin L. Giovanetti, Dr. Gabriel Niculescu, James Madison UniversityThe James Madison University Particle and Nuclear Physics Group, consisting of three faculty and a group of undergraduate students, conducts research in Intermediate Energy Nuclear Physics at Jefferson Lab (JLab), at Fermi National Lab (Fermilab), and at Paul Scherrer Institute (PSI). The aim of our group is to integrate important contributions to research with a quality educational experience for promising undergraduate students. The group members are actively involved in ongoing research in both Hall B and C at JLab (detector design and testing, data taking, data analysis). The group is also a key collaborator in the MULAN experiment (Muon Lifetime Experiment) underway at PSI and in the Minerva experiment (Neutrino-Nucleus Interactions) at Fermilab. These experiments are designed to explore the rich structure of the nucleons (proton or neutron), which are the basic building blocks of the atomic nucleus. It is widely held that protons and neutrons are built out of three quarks, viewed as fundamental particles, held together by gluonic forces. A complete picture of multi-quark systems (protons, neutrons, etc.) is not yet available. Studies that probe the structure of nucleons and nuclei, such as those in which our group participates at JLab and Fermilab, hope to clarify this picture. Of the four fundamental forces, the weak force is the only one that can change one fundamental particle into another. Recent theoretical and technological advancements have created the opportunity to improve our knowledge of the strength the weak force, by measuring the lifetime of the muon (MULAN experiment) with unprecedented precision. This allows the extraction of the Fermi coupling constant, which determines the strength of the weak force in the same manner as electric charge determines the strength of the electromagnetic force.