RUI: Testing QCD Symmetries via Precision Measurements of Light Pseudoscalar Mesons

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The Standard Model (SM) is a theory that describes fundamental particles in nature and the interactions between them. While the SM has been successful in explaining many phenomena observed in the laboratory to date, it offers no insight into experimental facts such as the dominance of matter over anti-matter, nor the nature of dark matter and dark energy, which are associated with the rotation curves of the galaxies and the accelerated expansion of the universe. Searching for physics beyond the Standard Model is therefore a well-motivated and important task for physicists. A good way to search for new physics is through tests of fundamental symmetries in different interactions.The goal of this project is to test fundamental symmetries in the electromagnetic and strong interactions via precision measurements on the properties of neutral particles: neutral pion and eta. The radiative decay width of the neutral pion plays a key role that bridges chiral symmetry spontaneous breaking and our understanding of QCD (a theory describing the strong interaction). On the other hand, the measurement of the eta radiative decay width will reveal the effect of explicit symmetry breakings of chiral symmetry, isospin, and SU(3) by the light-quark masses. In addition, the measurements of branching ratios or upper limits for various rare and forbidden decays of the eta will provide sensitive probes to test the violations of charge conjugation C, parity P, and time reversal T, as well as CP symmetries, and search for new physics beyond the Standard Model. The results of this project will provide clues to some important questions, such as: "why is our observed universe dominated by matter over anti-matter?", and "what are the masses of the light quarks?"This project will engage undergraduate students as key contributors. It will create a research-enriched learning environment, explore new approaches to recruiting prospective students, and develop new courses which are research related. Students working in an international collaboration will enhance their international experience and gain global perspectives.