Phys. Rev. Lett. 86, 4239–4242 (2001)Measuring the P-Odd Pion-Nucleon Coupling hπNN(1) in π+-Photoproton Production near ThresholdReceived 19 October 2000; revised 29 January 2001; published in the issue dated 7 May 2001 We show that γ⃗p→π+n in the threshold region is an excellent candidate for measuring the leading parity-violating pion-nucleon coupling hπNN(1) to an uncertainty of 20% if it has a natural size from dimensional analysis. The conclusion is based on a large unpolarized cross section, a new low-energy theorem for the photon polarization asymmetry at the threshold Aγ|th = √2fπ(μp-μn)hπNN(1)/gAmN∼hπNN(1)/2, and its strong dominance at forward and backward angles in the threshold region. © 2001 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.86.4239
DOI:
10.1103/PhysRevLett.86.4239
PACS:
13.60.Le, 11.30.Er, 11.30.Rd
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