[Jlab-seminars] Physics Hall D Seminar

[Patricia Cheeseboro]

Hall D Seminar

Drew Smith

March 28, 2024 9:00-9:55 A.M.

University of Massachusetts, Amherst

Zoom: https://jlab-org.zoomgov.com/j/1605062316?pwd=Z1dvRXJqc0Fmc0d6QkgzMTk5cFgvZz09

Preliminary Analysis of the PrimEx-eta Experiment in Hall D

Abstract:

The η meson is an interesting tool to study fundamental symmetries in low-energy QCD. In particular, the η→γγ decay proceeds primarily through the chiral anomaly, and its decay width is useful for providing critical input to extract fundamental parameters of QCD, such as the η-η' mixing angle and the light quark mass ratio. This decay width has been measured in the past using a fixed-target Primakoff experiment, however, its result shows tension with the average of the results from several e+e- collider experiments. To address this discrepancy and to reduce the total uncertainty for the decay width, the PrimEx-eta fixed-target experiment in Hall D at Jefferson Lab (E12-10-0111) is performing a precision measurement of the η→γγ decay width using the Primakoff method. The data collection was completed in three separate run periods between 2019 and 2022, and the full analysis is currently underway. In this talk, I will discuss the status of the experiment and show some preliminary results. Simultaneous with the η decay width measurement, the total cross section for Compton scattering off atomic electrons was measured. This well-understood QED process is used to verify the overall systematic uncertainties associated with a cross-section measurement in the forward direction, and provided one of the first absolute cross-section measurements in Hall D. In this talk, I will present the results for the integrated total Compton scattering cross section measurement and discuss the associated systematic uncertainties.

Patricia Cheeseboro
Admin Support Physics (Hall D)
Thomas Jefferson National Accelerator Facility
Jefferson Science Associates, LLC
pcheese at jlab.org<mailto:pcheese at jlab.org>
(757) 269-5345

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