The asymmetry of antimatter in the proton
Creators
- Dove, J.1
- Kerns, B.1
- McClellan, R. E.1, 2
- Miyasaka, S.
- Morton, D. H.3
- Nagai, K.4
- Prasad, S.1
- Sanftl, F.
- Scott, M. B. C.3
- Tadepalli, A. S.5, 2
- Aidala, C. A.3, 6
- Arrington, J.7, 8
- Ayuso, C.3, 9
- Barker, C. L.10
- Brown, C. N.11
- Chang, W. C.4
- Chen, A.1, 3, 4
- Christian, D. C.11
- Dannowitz, B. P.1
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Daugherity, M.10
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Diefenthaler, M.1, 2
- El Fassi, L.5, 9
- Geesaman, D. F.7
- Gilman, R.5
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Goto, Y.
- Guo, L.6, 12
- Guo, R.13
- Hague, T. J.10
- Holt, R. J.7, 14
- Isenhower, D.10
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Kinney, E. R.15
- Kitts, N.10
- Klein, A.6
- Kleinjan, D. W.6
- Kudo, Y.16
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Leung, C.1
- Lin, P.-J.15
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Liu, K.6
- Liu, M. X.6
- Lorenzon, W.3
- Makins, N. C. R.1
- Mesquita de Medeiros, M.7
- McGaughey, P. L.6
- Miyachi, Y.16
- Mooney, I.3, 17
- Nakahara, K.18, 19
- Nakano, K.
- Nara, S.16
- Peng, J.-C.1
- Puckett, A. J.6, 20
- Ramson, B. J.3, 11
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Reimer, P. E.7
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Rubin, J. G.3, 7
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Sawada, S.21
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Sawada, T.3
- Shibata, T.-A.22
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Su, D.4
- Teo, M.1, 23
- Tice, B. G.7
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Towell, R. S.10
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Uemura, S.6, 24
- Watson, S.10
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Wang, S. G.4, 13, 7
- Wickes, A. B.6
- Wu, J.11
- Xi, Z.10
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Ye, Z.7
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1.
University of Illinois Urbana-Champaign
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2.
Thomas Jefferson National Accelerator Facility
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3.
University of Michigan–Ann Arbor
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4.
Institute of Physics, Academia Sinica
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5.
Rutgers, The State University of New Jersey
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6.
Los Alamos National Laboratory
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7.
Argonne National Laboratory
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8.
Lawrence Berkeley National Laboratory
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9.
Mississippi State University
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10.
Abilene Christian University
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11.
Fermilab
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12.
Florida International University
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13.
National Kaohsiung Normal University
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14.
California Institute of Technology
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15.
University of Colorado Boulder
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16.
Yamagata University
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17.
Wayne State University
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18.
University of Maryland, College Park
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19.
SLAC National Accelerator Laboratory
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20.
University of Connecticut
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21.
High Energy Accelerator Research Organization
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22.
Nihon University
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23.
Stanford University
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24.
Tel Aviv University
Abstract
The fundamental building blocks of the proton—quarks and gluons—have been known for decades. However, we still have an incomplete theoretical and experimental understanding of how these particles and their dynamics give rise to the quantum bound state of the proton and its physical properties, such as its spin. The two up quarks and the single down quark that comprise the proton in the simplest picture account only for a few per cent of the proton mass, the bulk of which is in the form of quark kinetic and potential energy and gluon energy from the strong force. An essential feature of this force, as described by quantum chromodynamics, is its ability to create matter–antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions in which a matter–antimatter quark pair annihilates. In this picture of quark–antiquark creation by the strong force, the probability distributions as a function of momentum for the presence of up and down antimatter quarks should be nearly identical, given that their masses are very similar and small compared to the mass of the proton. Here we provide evidence from muon pair production measurements that these distributions are considerably different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momenta. These results are expected to revive interest in several proposed mechanisms for the origin of this antimatter asymmetry in the proton that had been disfavoured by previous results, and point to future measurements that can distinguish between these mechanisms.
Additional Information
© 2021 Nature Publishing Group. Received 02 June 2020; Accepted 15 December 2020; Published 24 February 2021. We thank G. T. Garvey for contributions to the early stages of this experiment. We also thank the Fermilab Accelerator Division and Particle Physics Division for their support of this experiment. This work was performed by the SeaQuest Collaboration, whose work was supported in part by the US Department of Energy under grants DE-AC02-06CH11357, DE-FG02-07ER41528, DE-SC0006963; the US National Science Foundation under grants PHY 0969239, PHY 1306126, PHY 1452636, PHY 1505458, PHY 1614456; the DP&A and ORED at Mississippi State University; the JSPS (Japan) KAKENHI through grant numbers 21244028, 25247037, 25800133; the Tokyo Tech Global COE Program, Japan; the Yamada Science Foundation of Japan; and the Ministry of Science and Technology (MOST), Taiwan. Fermilab is operated by Fermi Research Alliance, LLC, under contract number DE-AC02-07CH11359 with the US Department of Energy. Data availability: Raw data were generated at the Fermi National Accelerator Laboratory. Derived data supporting the findings of this study are available from the corresponding author upon request. Author Contributions: P.E.R. and D.F.G. are the co-spokespersons for the experiment. The entire SeaQuest Collaboration constructed the experiment and participated in the data collection and analysis. Substantial contributions to the cross-section ratio analysis were made by graduate students J.D., B.K., R.E.M., S.M., D.H.M., K. Nagai, S.P., F.S., M.B.C.S. and A.S.T. The development of the technique of extrapolation to zero intensity greatly benefited from the work of A.S.T. All authors reviewed the manuscript. The authors declare no competing interests. Peer review information: Nature thanks Gerald Miller, Gunar Schnell and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.Errata
Dove, J., Kerns, B., McClellan, R.E. et al. Publisher Correction: The asymmetry of antimatter in the proton. Nature (2022). https://doi.org/10.1038/s41586-022-04707-zAttached Files
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Supplemental Material - 41586_2021_3282_Tab1_ESM.jpg
Supplemental Material - 41586_2021_3282_Tab2_ESM.jpg
Supplemental Material - 41586_2021_3282_Tab3_ESM.jpg
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Additional details
Identifiers
- Eprint ID
- 108261
- Resolver ID
- CaltechAUTHORS:20210302-070239792
Related works
- Describes
- 10.1038/s41586-022-04707-z (DOI)
Funding
- Department of Energy (DOE)
- DE-AC02-06CH11357
- Department of Energy (DOE)
- DE-FG02-07ER41528
- Department of Energy (DOE)
- DE-SC0006963
- NSF
- PHY-0969239
- NSF
- PHY-1306126
- NSF
- PHY-1452636
- NSF
- PHY-1505458
- NSF
- PHY-1614456
- Mississippi State University
- Japan Society for the Promotion of Science (JSPS)
- 21244028
- Japan Society for the Promotion of Science (JSPS)
- 25247037
- Japan Society for the Promotion of Science (JSPS)
- 25800133
- Tokyo Tech Global COE Program
- Yamada Science Foundation
- Ministry of Science and Technology (Taipei)
- Department of Energy (DOE)
- DE-AC02-07CH11359
Dates
- Created
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2021-03-02Created from EPrint's datestamp field
- Updated
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2022-04-18Created from EPrint's last_modified field