Award Announcement - RUI: Hadron Structure and Interactions

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Award Materials

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The proton is a particle that is central to our understanding of matter in the universe. It is found in the nucleus of every atom and contributes to the fusion reactions that fuel the stars. Protons are constructed from basic building blocks of matter called quarks, antiquarks (the antimatter counterparts of the quarks) and gluons, but the ways in which these constituents contribute to the properties of the proton are not completely understood. For example, the proton has a property called spin, which is used in medical applications such as MRI scans, but detailed knowledge of how the spins of the quarks and gluons combine to give the spin of the proton is still missing. In this project the investigator will use theoretical models to study the contributions of strange quarks and antiquarks to the properties of the proton and compare the results to experimental measurements from facilities such as the Fermi National Accelerator Laboratory and the Jefferson National Accelerator Facility. Undergraduate students will participate in the project, receive training in nuclear and particle physics that is complementary to their undergraduate coursework and gain experience in research methods and scientific communication. The students will present their work at professional meetings and to the broader public.

The goal of this project is to determine the strangeness distributions of the proton and the contribution of strangeness to the proton's electromagnetic properties. Strangeness in the proton refers to its strange and anti-strange quarks, which are created by fluctuations of the proton into meson-baryon states or by quark and gluon interactions. Strangeness distributions describe the share of the proton's momentum that is carried by the strange or anti-strange quarks, which may differ from one another (strangeness asymmetry). Strangeness distributions are important both for our understanding of the structure of the proton, and because they affect the cross sections predicted for dark matter searches. The PI and her students will develop a meson cloud model to represent the fluctuations of the proton into pairs of strange mesons and strange baryons. A statistical model will be used to describe the strange distributions that are created in the mesons and baryons by quark and gluon interactions. Comparison will be made with experimental results for total strangeness and strangeness asymmetry. A light cone model of strangeness wave functions will be used to calculate strangeness electric and magnetic form factors, from which limits on strangeness in the nucleon can be determined from experimental measurements.