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arXiv · 1009.1681

A New Measurement of the $π^0$ Radiative Decay Width

I. Larin·D. McNulty·E. Clinton·P. Ambrozewicz·D. Lawrence·I. Nakagawa·Y. Prok·A. Teymurazyan·A. Ahmidouch·A. Asratyan·K. Baker·L. Benton·A. M. Bernstein·V. Burkert·P. Cole·P. Collins·D. Dale·S. Danagoulian·G. Davidenko·R. Demirchyan·A. Deur·A. Dolgolenko·G. Dzyubenko·R. Ent·A. Evdokimov·J. Feng·M. Gabrielyan·L. Gan·A. Gasparian·S. Gevorkyan·A. Glamazdin·V. Goryachev·V. Gyurjyan·K. Hardy·J. He·M. Ito·L. Jiang·D. Kashy·M. Khandaker·P. Kingsberry·A. Kolarkar·M. Konchatnyi·A. Korchin·W. Korsch·S. Kowalski·M. Kubantsev·V. Kubarovsky·X. Li·P. Martel·V. Matveev·B. Mecking·B. Milbrath·R. Minehart·R. Miskimen·V. Mochalov·S. Mtingwa·S. Overby·E. Pasyuk·M. Payen·R. Pedroni·B. Ritchie·T. E. Rodrigues·C. Salgado·A. Shahinyan·A. Sitnikov·D. Sober·S. Stepanyan·W. Stephens·J. Underwood·A. Vasiliev·V. Vishnyakov·M. Wood·S. Zhou
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Abstract

High precision measurements of the differential cross sections for $π^0$ photoproduction at forward angles for two nuclei, $^{12}$C and $^{208}$Pb, have been performed for incident photon energies of 4.9 - 5.5 GeV to extract the ${π^0 \to γγ}$ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ${π^0 \to γγ}$ 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 $Γ{(π^0 \to γγ)} = 7.82 \pm 0.14 ~({\rm stat.}) \pm 0.17 ~({\rm syst.}) ~{\rm eV}$. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current PDG average of this fundamental quantity and it is consistent with current theoretical predictions.

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I. Larin, D. McNulty, E. Clinton, P. Ambrozewicz, D. Lawrence, I. Nakagawa, Y. Prok, A. Teymurazyan, A. Ahmidouch, A. Asratyan, K. Baker, L. Benton, A. M. Bernstein, V. Burkert, P. Cole, P. Collins, D. Dale, S. Danagoulian, G. Davidenko, R. Demirchyan, A. Deur, A. Dolgolenko, G. Dzyubenko, R. Ent, A. Evdokimov, J. Feng, M. Gabrielyan, L. Gan, A. Gasparian, S. Gevorkyan, A. Glamazdin, V. Goryachev, V. Gyurjyan, K. Hardy, J. He, M. Ito, L. Jiang, D. Kashy, M. Khandaker, P. Kingsberry, A. Kolarkar, M. Konchatnyi, A. Korchin, W. Korsch, S. Kowalski, M. Kubantsev, V. Kubarovsky, X. Li, P. Martel, V. Matveev, B. Mecking, B. Milbrath, R. Minehart, R. Miskimen, V. Mochalov, S. Mtingwa, S. Overby, E. Pasyuk, M. Payen, R. Pedroni, B. Ritchie, T. E. Rodrigues, C. Salgado, A. Shahinyan, A. Sitnikov, D. Sober, S. Stepanyan, W. Stephens, J. Underwood, A. Vasiliev, V. Vishnyakov, M. Wood, S. Zhou. 2010-09-09. A New Measurement of the $π^0$ Radiative Decay Width. https://doi.org/10.1103/physrevlett.106.162303

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