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Title: Precision Measurement of {eta} --> {gamma} {gamma} Decay Width via the Primakoff Effect

A precision measurement of the {eta} --> {gamma} {gamma} decay width via the Primakoff effect is underway in Hall D at Jefferson Lab. The decay width will be extracted from measured differential cross sections at forward angles on two light targets, liquid hydrogen and 4He, using a 11.5 GeV tagged photon beam. Results of this experiment will not only potentially resolve a long standing discrepancy between the Primakoff and the collider measurements, but will also reduce the experimental uncertainty by a factor of two on the average value of previous experimental results listed by the Particle Data Group(PDG). It will directly improve all other eta partial decay widths which rely on the accuracy of the eta radiative decay width. The projected 3% precision on the {Gamma}({eta} --> {gamma} {gamma} ) measurement will have a significant impact on the experimental determination of the fundamental parameters in QCD, such as the ratio of light quark masses (m{sub u},m{sub d},m{sub s}) and the {eta} - {eta}' mixing angle. It will be a sensitive probe for understanding QCD symmetries and the origin and the dynamics of QCD symmetry breaking.
Authors:
 [1]
  1. University of North Carolina at Wilmington, JLAB
Publication Date:
OSTI Identifier:
1092542
Report Number(s):
JLAB-PHY-12-1689; DOE/OR/23177-2751
DOE Contract Number:
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Journal Name: Proceedings of Science; Journal Volume: CD12; Conference: CD 12, August 6 -10, 2012, Newport News, Virginia, USA
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS