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ABACHI 1995G

D0 collaboration; Abachi, S. et al.
Observation of the Top Quark
Phys. Rev. Lett. 74 (1995) 2632;

Abstracts
The D0 Collaboration reports on a search for the standard model top quark in p collisions at = 1.8 TeV at the Fermilab Tevatron with an integrated luminosity of approximately 50 pb^-1. We have searched for t production in the dilepton and single-lepton decay channels with and without tagging of b-quark jets. We observed 17 events with an expected background of 3.8 ± 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 x 10^-6 (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measured its mass to be 199⁺¹⁹_-21(stat) ± 22(syst) GeV/c² and its cross section to be 6.4 ± 2.2 pb.

Accelerator FNAL-COLLIDER Detectors D0

Related references
More (earlier) information appears in
S. Abachi et al., Phys. Rev. Lett. 72 (1994) 2138;
See also
F. Abe et al., Phys. Rev. Lett. 73 (1994) 225;
F. Abe et al., Phys. Rev. D50 (1994) 2966;

Reactions

	p + e– 2jet X	1.8 TeV (Ecm)	pt, et, mass
	p – e+ 2jet X	1.8 TeV (Ecm)	pt, et, mass
	p – + 2jet X	1.8 TeV (Ecm)	pt, et, mass
	p e– e+ 2jet X	1.8 TeV (Ecm)	pt, et, mass
	p + e– 3jet X	1.8 TeV (Ecm)	pt, et, mass
	p + e+ 3jet X	1.8 TeV (Ecm)	pt, et, mass
	p 2+ 3jet X	1.8 TeV (Ecm)	pt, et, mass
	p – e– 3jet X	1.8 TeV (Ecm)	pt, et, mass
	p – e+ 3jet X	1.8 TeV (Ecm)	pt, et, mass
	p – + 3jet X	1.8 TeV (Ecm)	pt, et, mass
	p e+ 4jet X	1.8 TeV (Ecm)	pt, et, mass
	p e– 4jet X	1.8 TeV (Ecm)	pt, et, mass
	p – 4jet X	1.8 TeV (Ecm)	pt, et, mass
	p + 4jet X	1.8 TeV (Ecm)	pt, et, mass
	p t X	1.8 TeV (Ecm)	cs
	W+ e+ e
	W– e– e
	W+ +
	W– –
	t W+ b
	W–
	W+ 2jet
	W– 2jet
	b jet
	b – X
	jet
	+ X

Particles studied

	t	ex, mass
		ex, mass

Record comments
Observation of the top quark. D0 Collaboration.

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