Study of prompt <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>η</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math>, and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>ω</mi></mrow><mrow><mn>0</mn></mrow></msup></mrow></math> production in low-energy <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mrow><mover><mrow><mi>p</mi></mrow><mrow><mi>¯</mi></mrow></mover></mrow></mrow><mi></mi><mi>p</mi></math> annihilations

G. Levman; R. Singer; T. Fields

doi:10.1103/PhysRevD.21.1

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Study of prompt $e^{+} e^{-}$ , $η^{0}$ , and $ω^{0}$ production in low-energy $\bar{p} p$ annihilations

G. Levman, R. Singer, and T. Fields

Argonne National Laboratory, Argonne, Illinois 60439

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Phys. Rev. D 21, 1 – Published 1 January, 1980

DOI: https://doi.org/10.1103/PhysRevD.21.1

Abstract

A study of prompt $e^{+} e^{-}$ production has been made using the Argonne 12-foot bubble chamber exposed to a low-energy $\bar{p}$ beam. We found eleven annihilation events with $e^{+} e^{-}$ pairs of invariant mass greater than the $π^{0}$ mass. The background to direct $e^{+} e^{-}$ pair production comes mainly from $η^{0} \to γ e^{+} e^{-}$ and $ω^{0} \to π^{0} e^{+} e^{-}$ Dalitz pairs. To determine these backgrounds, we have measured the inclusive $η^{0}$ and $ω^{0}$ production rates using externally converted $γ$ rays. We find $\frac{ω^{0}}{π^{0}} = 0.20 \pm 0.07$ and $\frac{η^{0}}{π^{0}} < 0.11$ at the 90% confidence level. The ( $η^{0} + ω^{0}$ ) Dalitz background plus other small backgrounds yield ${7.0}_{- 3.0}^{+ 44}$ events. The remaining events yield a 90%-confidence-level upper limit for the ratio of prompt $e^{+} e^{-}$ pairs to $π^{0}$ production of 4 × $10^{- 5}$ .

References (24)

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Omitted endnote
J. P. Boymond et al., Phys. Rev. Lett. 33, 112 (1974)
J. A. Appel et al., Phys. Rev. Lett. 33, 722 (1974)
D. Bintinger et al., Phys. Rev. Lett. 35, 72 (1975)
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E. W. Beier et al., Phys. Rev. Lett. 37, 1117 (1976)
Y. Makdisi et al., Phys. Rev. Lett. 41, 367 (1978)
J. H. Cobb et al., Phys. Lett. 78B, 519 (1978)
J. Guy et al., Phys. Lett. 66B, 300 (1977)
H. Muirhead et al., Phys. Lett. 66B, 483 (1977)
T. N. Rangaswamy et al., Tata Institute of Fundamental Research Report No. TIFR-BC-78-4 (unpublished)
J. Ballam et al., Phys. Rev. Lett. 41, 1207 (1978)
J. Ballam et al., Phys. Rev. Lett. 40, 741 (1978)
K. Bunnell et al., Phys. Rev. Lett. 40, 136 (1978)
W. Morse et al., Phys. Rev. D 18, 3145 (1978) D. M. Grannan et al., ibid. 18, 3150 (1978)
G. Levman, R. Singer, and T. Fields, in Proceedings of the Fourth European Antiproton Conference, Strasbourg, 1978, edited by A. Fridman (Centre National de la Researche Scientifique, Paris, 1979)
J. Roy, in Proceedings of the Fourth International Symposium on $\bar{N}$ N Interactions, Syracuse, New York, 1975, edited by T. E. Kalogeropoulos and K. C. Wali (Syracuse University, Syracuse, 1975)
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Based on data from the Particle Data Group, Report No. CERN/HERA 73-1 (unpublished) [24]
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[c1] J. W. Cronin, in Proceedings of the International Symposium on Lepton and Photon Interactions at High Energies, Hamburg, 1977, edited by F. Gutbrod (DESY, Hamburg, 1977) N. S. Craigie, Phys. Rep. 47, 1 (1978)

[c2] Omitted endnote

[c3] J. P. Boymond et al., Phys. Rev. Lett. 33, 112 (1974)

[c4] J. A. Appel et al., Phys. Rev. Lett. 33, 722 (1974)

[c5] D. Bintinger et al., Phys. Rev. Lett. 35, 72 (1975)

[c6] F. W. Busser et al., Phys. Lett. 53B, 212 (1974)

[c7] L. Baum et al., Phys. Lett. 60B, 485 (1976)

[c8] E. W. Beier et al., Phys. Rev. Lett. 37, 1117 (1976)

[c9] Y. Makdisi et al., Phys. Rev. Lett. 41, 367 (1978)

[c10] J. H. Cobb et al., Phys. Lett. 78B, 519 (1978)

[c11] J. Guy et al., Phys. Lett. 66B, 300 (1977)

[c12] H. Muirhead et al., Phys. Lett. 66B, 483 (1977)

[c13] T. N. Rangaswamy et al., Tata Institute of Fundamental Research Report No. TIFR-BC-78-4 (unpublished)

[c14] J. Ballam et al., Phys. Rev. Lett. 41, 1207 (1978)

[c15] J. Ballam et al., Phys. Rev. Lett. 40, 741 (1978)

[c16] K. Bunnell et al., Phys. Rev. Lett. 40, 136 (1978)

[c17] W. Morse et al., Phys. Rev. D 18, 3145 (1978) D. M. Grannan et al., ibid. 18, 3150 (1978)

[c18] G. Levman, R. Singer, and T. Fields, in Proceedings of the Fourth European Antiproton Conference, Strasbourg, 1978, edited by A. Fridman (Centre National de la Researche Scientifique, Paris, 1979)

[c19] J. Roy, in Proceedings of the Fourth International Symposium on $\bar{N}$ N Interactions, Syracuse, New York, 1975, edited by T. E. Kalogeropoulos and K. C. Wali (Syracuse University, Syracuse, 1975)

[c20] N. M. Kroll and W. Wada, Phys. Rev. 98, 1355 (1955)

[c21] C. M. Lai and C. Quigg, Fermilab Report No. FN-296, 1976 (unpublished)

[c22] Based on data from the Particle Data Group, Report No. CERN/HERA 73-1 (unpublished) [24]

[c23] R. Hamatsu et al., Nucl. Phys. B123, 189 (1977) C. K. Chen et al., Phys. Rev. D 17, 42 (1978)

[c24] E. Fett et al., Phys. Lett. 59B, 182 (1975) [22]

Physical Review D

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Study of prompt $e^{+} e^{-}$ , $η^{0}$ , and $ω^{0}$ production in low-energy $\bar{p} p$ annihilations

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Study of prompt e+e−, η0, and ω0 production in low-energy p¯p annihilations

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References (24)

Study of prompt $e^{+} e^{-}$ , $η^{0}$ , and $ω^{0}$ production in low-energy $\bar{p} p$ annihilations