Precision measurement of the neutral pion lifetime

Larin, I. et al. (2020) Precision measurement of the neutral pion lifetime. Science, 368(6490), pp. 506-509. (doi: 10.1126/science.aay6641) (PMID:32355026)

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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 π into two photons (γγ), leading to its unusually short lifetime. We precisely measured the decay width Γ of the [Formula: see text] process. The differential cross sections for π photoproduction at forward angles were measured on two targets, carbon-12 and silicon-28, yielding [Formula: see text], 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 [Formula: see text] Our final result has a total uncertainty of 1.50% and confirms the prediction based on the chiral anomaly in quantum chromodynamics.

Item Type:Articles
Additional Information:This project was supported in part by the National Science Foundation under a Major Research Instrumentation grant (PHY- 0079840) and by the U.S. Department of Energy, including contract no. DE-AC05-06OR23177 under which the Jefferson Science Associates, LLC, operates Thomas Jefferson National Accelerator Facility.
Glasgow Author(s) Enlighten ID:Protopopescu, Dr Dan
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., Gevorkyan, S., Glamazdin, A., Guo, L., Isupov, E., Ito, M.M., Klein, F., Kowalski, S., Kubarovsky, A., Kubarovsky, V., Lawrence, D., Lu, H., Ma, L., Matveev, V., Morrison, B., Micherdzinska, A., Nakagawa, I., Park, K., Pedroni, R., Phelps, W., Protopopescu, D., Rimal, D., Romanov, D., Salgado, C., Shahinyan, A., Sober, D., Stepanyan, S., Tarasov, V.V., Taylor, S., Vasiliev, A., Wood, M., Ye, L., and Zihlmann, B.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Science
Publisher:American Association for the Advancement of Science
ISSN (Online):1095-9203
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in Science 368(6490):506-509
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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