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  • New Measurement of the {pi}...
    Larin, I.; North Carolina A and T State University, Greensboro, North Carolina 27411; McNulty, D.; Prok, Y.; Bernstein, A. M.; Kowalski, S.; Clinton, E.; Martel, P.; Miskimen, R.; Wood, M.; Ambrozewicz, P.; Ahmidouch, A.; Benton, L.; Danagoulian, S.; Demirchyan, R.; Gasparian, A.; Hardy, K.; Mtingwa, S.; Overby, S.; Payen, M.; Pedroni, R.

    Physical review letters, 04/2011, Letnik: 106, Številka: 16
    Journal Article

    High precision measurements of the differential cross sections for {pi}{sup 0} photoproduction at forward angles for two nuclei, {sup 12}C and {sup 208}Pb, have been performed for incident photon energies of 4.9-5.5 GeV to extract the {pi}{sup 0}{yields}{gamma}{gamma} decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The {pi}{sup 0}{yields}{gamma}{gamma} decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is {Gamma}({pi}{sup 0}{yields}{gamma}{gamma})=7.82{+-}0.14(stat){+-}0.17(syst) eV. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.