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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 MM, 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 VV, Taylor S, Vasiliev A, Wood M, Ye L, Zihlmann B. Precision measurement of the neutral pion lifetime. Science 2020; 368:506-509. [PMID: 32355026 DOI: 10.1126/science.aay6641] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 03/30/2020] [Indexed: 11/02/2022]
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 π0 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 π0 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.
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Affiliation(s)
- I Larin
- Alikhanov Institute for Theoretical and Experimental Physics, National Research Center (NRC) "Kurchatov Institute," Moscow, 117218, Russia.,Department of Physics, University of Massachusetts, Amherst, MA 01003, USA
| | - Y Zhang
- Department of Physics, Duke University, Durham, NC 27708, USA.,Triangle Universities Nuclear Laboratory, Durham, NC 27708, USA
| | - A Gasparian
- Department of Physics, North Carolina A&T State University, Greensboro, NC 27411, USA.
| | - L Gan
- Department of Physics and Physical Oceanography, University of North Carolina Wilmington, Wilmington, NC 28403, USA
| | - R Miskimen
- Department of Physics, University of Massachusetts, Amherst, MA 01003, USA
| | - M Khandaker
- Department of Physics, Norfolk State University, Norfolk, VA 23504, USA
| | - D Dale
- Department of Physics and Nuclear Engineering, Idaho State University, Pocatello, ID 83209, USA
| | - S Danagoulian
- Department of Physics, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - E Pasyuk
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - H Gao
- Department of Physics, Duke University, Durham, NC 27708, USA.,Triangle Universities Nuclear Laboratory, Durham, NC 27708, USA
| | - A Ahmidouch
- Department of Physics, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - P Ambrozewicz
- Department of Physics, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - V Baturin
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - V Burkert
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - E Clinton
- Department of Physics, University of Massachusetts, Amherst, MA 01003, USA
| | - A Deur
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - A Dolgolenko
- Alikhanov Institute for Theoretical and Experimental Physics, National Research Center (NRC) "Kurchatov Institute," Moscow, 117218, Russia
| | - D Dutta
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, MS 39762, USA
| | - G Fedotov
- Department of Physics, Moscow State University, Moscow 119991, Russia.,B. P. Konstantinov Petersburg Nuclear Physics Institute, NRC "Kurchatov Institute," Gatchina, St. Petersburg, 188300, Russia
| | - J Feng
- Department of Physics and Physical Oceanography, University of North Carolina Wilmington, Wilmington, NC 28403, USA
| | - S Gevorkyan
- Joint Institute for Nuclear Research, Dubna, 141980, Russia
| | - A Glamazdin
- Kharkov Institute of Physics and Technology, Kharkov, 310108, Ukraine
| | - L Guo
- Department of Physics, Florida International University, Miami, FL 33199, USA
| | - E Isupov
- Department of Physics, Moscow State University, Moscow 119991, Russia
| | - M M Ito
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - F Klein
- Department of Physics, The Catholic University of America, Washington, DC 20064, USA
| | - S Kowalski
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - A Kubarovsky
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - V Kubarovsky
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - D Lawrence
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - H Lu
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
| | - L Ma
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China
| | - V Matveev
- Alikhanov Institute for Theoretical and Experimental Physics, National Research Center (NRC) "Kurchatov Institute," Moscow, 117218, Russia
| | - B Morrison
- Department of Physics, Arizona State University, Tempe, AZ 85281, USA
| | - A Micherdzinska
- Department of Physics, George Washington University, Washington, DC 20064, USA
| | - I Nakagawa
- RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama 351-0198, Japan
| | - K Park
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - R Pedroni
- Department of Physics, North Carolina A&T State University, Greensboro, NC 27411, USA
| | - W Phelps
- Department of Physics, Computer Science and Engineering, Christopher Newport University, Newport News, VA 23606, USA
| | - D Protopopescu
- School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
| | - D Rimal
- Department of Physics, Florida International University, Miami, FL 33199, USA
| | - D Romanov
- Department of Physics, Moscow Engineering Physics Institute, Moscow, Russia
| | - C Salgado
- Department of Physics, Norfolk State University, Norfolk, VA 23504, USA
| | - A Shahinyan
- Yerevan Physics Institute, Yerevan 0036, Armenia
| | - D Sober
- Department of Physics, The Catholic University of America, Washington, DC 20064, USA
| | - S Stepanyan
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - V V Tarasov
- Alikhanov Institute for Theoretical and Experimental Physics, National Research Center (NRC) "Kurchatov Institute," Moscow, 117218, Russia
| | - S Taylor
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
| | - A Vasiliev
- Institute for High Energy Physics, NRC "Kurchatov Institute," Protvino, 142281, Russia
| | - M Wood
- Department of Physics, University of Massachusetts, Amherst, MA 01003, USA
| | - L Ye
- Department of Physics and Astronomy, Mississippi State University, Mississippi State, MS 39762, USA
| | - B Zihlmann
- Thomas Jefferson National Accelerator Facility, Newport News, VA 23606, USA
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