학술논문
A New Measurement of the $\pi^0$ Radiative Decay Width
Document Type
Working Paper
Author
Larin, I.; McNulty, D.; Clinton, E.; Ambrozewicz, P.; Lawrence, D.; Nakagawa, I.; Prok, Y.; Teymurazyan, A.; Ahmidouch, A.; Asratyan, A.; Baker, K.; Benton, L.; Bernstein, A. M.; Burkert, V.; Cole, P.; Collins, P.; Dale, D.; Danagoulian, S.; Davidenko, G.; Demirchyan, R.; Deur, A.; Dolgolenko, A.; Dzyubenko, G.; Ent, R.; Evdokimov, A.; Feng, J.; Gabrielyan, M.; Gan, L.; Gasparian, A.; Gevorkyan, S.; Glamazdin, A.; Goryachev, V.; Gyurjyan, V.; Hardy, K.; He, J.; Ito, M.; Jiang, L.; Kashy, D.; Khandaker, M.; Kingsberry, P.; Kolarkar, A.; Konchatnyi, M.; Korchin, A.; Korsch, W.; Kowalski, S.; Kubantsev, M.; Kubarovsky, V.; Li, X.; Martel, P.; Matveev, V.; Mecking, B.; Milbrath, B.; Minehart, R.; Miskimen, R.; Mochalov, V.; Mtingwa, S.; Overby, S.; Pasyuk, E.; Payen, M.; Pedroni, R.; Ritchie, B.; Rodrigues, T. E.; Salgado, C.; Shahinyan, A.; Sitnikov, A.; Sober, D.; Stepanyan, S.; Stephens, W.; Underwood, J.; Vasiliev, A.; Vishnyakov, V.; Wood, M.; Zhou, S.
Source
Phys.Rev.Lett.106:162303,2011
Subject
Language
Abstract
High precision measurements of the differential cross sections for $\pi^0$ 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 ${\pi^0 \to \gamma\gamma}$ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ${\pi^0 \to \gamma\gamma}$ 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 $\Gamma{(\pi^0 \to \gamma\gamma)} = 7.82 \pm 0.14 ~({\rm stat.}) \pm 0.17 ~({\rm syst.}) ~{\rm eV}$. 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.
Comment: 4 pages, 5 figures
Comment: 4 pages, 5 figures