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Spin Precession Methods

First Extraction of the Pretzelosity Distribution

Student: Christopher Lefky

School: Creighton University

Mentored By: Alexei Prokudin

This project was motivated partly due to the proton spin puzzle, which is the problem of how the spin of the proton is distributed amongst its quark and gluon components. The pretzelosity function exists among the transverse momentum dependent (TMD) distributions and is directly related to the orbital angular momentum (OAM) of quarks. This project explores the pretzelosity function using recent data from HERMES to understand whether the data suggest a non-zero pretzelosity. The present errors of the experimental data are too great to determine the pretzelosity precisely. Extracting the pretzelosity function offers insight into the contribution of the OAM of quarks to the spin of the proton. The future Jefferson Lab 12 GeV data will be essential for determining the pretzelosity.
First Extraction of the Pretzelosity Distribution