The system of π0, η and η′ offers a flavor-conserving laboratory to test the low-energy QCD and to search for new physics Beyond the Standard Model. The symmetrical properties of QCD at low-energy, such as the chiral symmetry or the axial anomalies, are manifested in decays of these mesons. Thus, a study of π0, η and η′ will yield light on our understanding of the origin and the dynamics of QCD confinement. In addition, the η/η′ meson has quantum numbers of vacuum (except parity) with its strong and electromagnetic decays being either anomalous or forbidden to the lowest order due to symmetries or angular momentum conservation. This enhances the relative importance of higher order contributions, making rare η/η′ decays a sensitive hadronic probe for weakly-coupled new forces. Searching for sub-GeV dark gauge boson candidates and the C-violating, P-conserving interactions in various η/η′ decays will extend our knowledge of the dark sector and explore new sources of CP violation that are needed to explain the observed matter and anti-matter asymmetry in the universe. An overview of physics, the status of experimental activities at Jefferson Lab, and the future new opportunities in the light meson decays will be presented.
Biography: Liping Gan is a professor of physics at University of North Carolina Wilmington. She received Ph.D. in physics from University of Manitoba in Canada, M.S. and B.S. in physics from Peking University in China. Her research interests focus on confinement QCD, fundamental symmetries, and new physics beyond the standard model via measurements of the light meson decays. She has lead several experiments at Jefferson Lab as a spokesperson: the PrimEx-II experiment, a precision measurement of the π0 lifetime; the PrimEx-eta experiment, a measurement of the η radiative decay width; the JLab Eta factory (JEF) experiment, a study of η/η´ decays with emphasis on rare modes; and the π0-TFF experiment, a measurement of the π0 space-like transition form factor.
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Prof. Qiang Li