New Measurement of the π0 Radiative Decay Width

作者：I. Larin, D. McNulty, Eric Clinton, Pawel Ambrozewicz, David Lawrence, I. Nakagawa, Y. Prok, Aram Teymurazyan, A. Ahmidouch, A.E. Asratyan, Keith Baker, Larry D. Benton, A. M. Bernstein, V. D. Burkert, P. L. Cole, P. Collins, Daniel S. Dale, S. Danagoulian, G.V. Davidenko, R. Demirchyan, A. Deur, A. Dolgolenko, G.B. Dzyubenko, R. Ent, Anatoly Evdokimov, Jie Feng, M. Gabrielyan, L. Gan, A. Gasparian, S. R. Gevorkyan, A. Glamazdin, V. Goryachev, V. Gyurjyan, Kenneth A. Hardy, Jun He, M. M. Ito, Lijun Jiang, David H. Kashy, M. Khandaker, P. Kingsberry, Ameya Kolarkar, M. I. Konchatnij, A. Yu. Korchin, W. Korsch, Seweryn Kowalski, M. Kubantsev, V. Kubarovsky, X. Li, P. P. Martel, Viktor A. Matveev, Bernhard A. Mecking, Brian D. Milbrath, Ralph C. Minehart, Rory Miskimen, В. В. Мочалов, Sekazi K. Mtingwa, S. Overby, E. Pasyuk, M. Payen, R. S. Pedroni, B. G. Ritchie, T. E. Rodrigues, Carlos W. Salgado, Albert Shahinyan, A. L. Sitnikov, D. I. Sober, Stepan Stepanyan, William A. Stephens, Jonathan G. Underwood, Alexander L. Vasiliev, V.E. Vishnyakov, M. H. Wood, S. Zhou · 发表于：Physical Review Letters · 年份：2011 · DOI：10.1103/physrevlett.106.162303 · 被引用次数：107 · 研究领域：Particle physics theoretical and experimental studies、Quantum Chromodynamics and Particle Interactions、Nuclear physics research studies

High precision measurements of the differential cross sections for ${\ensuremath{\pi}}^{0}$ photoproduction at forward angles for two nuclei, $^{12}\mathrm{C}$ and $^{208}\mathrm{Pb}$, have been performed for incident photon energies of 4.9--5.5 GeV to extract the ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$ 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 $\ensuremath{\Gamma}({\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})=7.82\ifmmode\pm\else\textpm\fi{}0.14(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.17(\mathrm{syst})\text{ }\text{ }\mathrm{eV}$. 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.