Preliminary Results from the PrimEx-II experiment at Jefferson Lab

Conference · Wed Jun 01 00:00:00 EDT 2016 · Proceedings of Science

OSTI ID:1262743

Gasparian, Ashot ^[1]

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1. NCA&T, Greensboro, NC; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

Properties of the neutral pion, as the lightest hadron in Nature, are most sensitive to the basic symmetries and their partial breaking effects in the theory of the strong interaction (QCD). In particular, the po →gg decay width is primarily defined by the spontaneous chiral symmetry breaking effect (chiral anomaly) in QCD. The next order corrections to the anomaly have been shown to be small and are known to a 1% precision level. The PrimEx Collaboration at JLab has developed and performed two Primakoff type experiments to measure the po →gg decay width with a similar precision. The published result from the PrimEx-I experiment, G(p0 →gg ) = 7.82±0.14 (stat.)±0.17 (syst.) eV, was a factor of two more precise than the average value quoted in PDG-2010 [1]. The second experiment was performed in 2010 with a goal of 1.4% total uncertainty to address the next-to-leading-order theory calculations. The preliminary results from the PrimEx-II experiment are presented and discussed in this note.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177; PHY-1506388; PHY-1205962; PHY-0079840
• OSTI ID: 1262743
• Report Number(s): JLAB-PHY-15-2158; DOE/OR/23177-3846
• Journal Information: Proceedings of Science, Vol. CD15; Conference: Chiral Dynamics (CD15) : Pisa, Italy, June 29-July 3, 2015
• Country of Publication: United States
• Language: English