Precision measurement of the neutral pion lifetime.
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| Title: | Precision measurement of the neutral pion lifetime. |
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| Authors: | Larin, I., Zhang, Y., Gasparian, A., Gan, L., Miskimen, R., Khandaker, M., Dale, D., Danagoulian, S., Pasyuk, E., Gao, H., Ahmidouch, A., Ambrozewicz, P., Baturin, V., Burkert, V., Clinton, E., Deur, A., Dolgolenko, A., Dutta, D., Fedotov, G., Feng, J. |
| Source: | Science (pre-March 2025). 5/1/2020, Vol. 368 Issue 6490, p506-509. 4p. 3 Color Photographs. |
| Subjects: | Symmetry, Quantum fluctuations, Neutral pion, Photons, Quantum chromodynamics |
| Abstract: | The explicit breaking of the axial symmetry by quantum fluctuations gives rise to the so-called axial anomaly. This phenomenon is solely responsible for the decay of the neutral pion p0 into two photons (gg), leading to its unusually short lifetime. We precisely measured the decay width G of the p0 → gg process. The differential cross sections for p0 photoproduction at forward angles were measured on two targets, carbon-12 and silicon-28, yielding G(p0 → gg) = 7.798 ± 0.056(stat.) ± 0.109(syst.) eV, where stat. denotes the statistical uncertainty and syst. the systematic uncertainty. We combined the results of this and an earlier experiment to generate a weighted average of G(p0 → gg) = 7.802 ± 0.052(stat.) ± 0.105(syst.) eV. Our final result has a total uncertainty of 1.50% and confirms the prediction based on the chiral anomaly in quantum chromodynamics. [ABSTRACT FROM AUTHOR] |
| Copyright of Science (pre-March 2025) is the property of American Association for the Advancement of Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Psychology and Behavioral Sciences Collection |
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