Properties of six jet events with large six jet mass at the Fermilab proton - anti-proton collider

The CDF collaboration Abe, F. ; Akimoto, H. ; Akopian, A. ; et al.
Phys.Rev.D 56 (1997) 2532-2543, 1997.
Inspire Record 442265 DOI 10.17182/hepdata.53980

We describe the properties of six-jet events, with the six-jet mass exceeding 520GeV/c2, produced at the Fermilab proton-antiproton collider operating at a center-of-mass energy of 1.8 TeV. Observed distributions for a set of 20 multijet variables are compared with predictions from the HERWIG QCD parton shower Monte Carlo program, the NJETS leading order QCD matrix element Monte Carlo program, and a phase-space model in which six-jet events are distributed uniformly over the kinematically allowed region of the six-body phase space. In general the QCD predictions provide a good description of the observed six-jet distributions.

18 data tables

The 6Jet mass spectrum.

Dalitz X distribution for jet 3 in the reduced 3-JET final state.

Dalitz X distribution for jet 4 in the reduced 3-JET final state.

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First observation of the all hadronic decay of t anti-t pairs

The CDF collaboration Abe, F. ; Akimoto, H. ; Akopian, A. ; et al.
Phys.Rev.Lett. 79 (1997) 1992-1997, 1997.
Inspire Record 441462 DOI 10.17182/hepdata.42211

We present the first observation of the all hadronic decay of tt¯ pairs. The analysis is performed using 109pb−1 of pp¯ collisions at s=1.8TeV collected with the Collider Detector at Fermilab. We observe an excess of events with five or more jets, including one or two b jets, relative to background expectations. Based on this excess we evaluate the production cross section to be in agreement with previous results. We measure the top mass to be 186±10±12GeV/c2.

2 data tables

The cross section is given in the paper at a TQ mass of 175 GeV. The values at TQ mass = (175 +- 10) GeV is evaluated as +20% and -12% as given in the paper. The statistical error has also been scaled.

The measured value of the top mass.


J / psi and psi (2S) production in p anti-p collisions at s**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Akimoto, H. ; Akopian, A. ; et al.
Phys.Rev.Lett. 79 (1997) 572-577, 1997.
Inspire Record 440101 DOI 10.17182/hepdata.42223

We present a study of J/ψ and ψ(2S) production in pp¯ collisions, at s=1.8TeV with the CDF detector at Fermilab. The J/ψ and ψ(2S) mesons are reconstructed using their μ+μ− decay modes. We have measured the inclusive production cross section for both mesons as a function of their transverse momentum in the central region, |η|<0.6. We also measure the fraction of these events originating from b hadrons. We thus extract individual cross sections for J/ψ and ψ(2S) mesons from b-quark decays and prompt production. We find a large excess (approximately a factor of 50) of direct ψ(2S) production compared with predictions from the color singlet model.

5 data tables

Integrated cross sections.

Differential cross section times branching ratio for J/PSI's originating from b hadron decays.

Differential cross section times branching ratio for PSI(2S) originating from b hadron decays.

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Production of J / psi mesons from chi(c) meson decays in p anti-p collisions at s**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Akimoto, H. ; Akopian, A. ; et al.
Phys.Rev.Lett. 79 (1997) 578-583, 1997.
Inspire Record 440446 DOI 10.17182/hepdata.42231

We have measured the fraction of J/ψ mesons originating from χc meson decays in pp¯ collisions at s=1.8TeV. The fraction, for PTJ/ψ>4.0GeV/c and |ηJ/ψ|<0.6, not including contributions from b flavored hadrons, is 29.7%±1.7%(stat)±5.7%(syst). We have determined the cross sections for J/ψ mesons originating from χc decays and for directly produced J/ψ mesons. We have found that direct J/ψ production is in excess of the prediction of the color singlet model by the same factor found for direct ψ(2S) production.

4 data tables

Fraction of J/PSI mesons from CHI/C decays, excluding the the contributions from b-hadron decay.

Differential cross section for J/PSI's directly produced (ie excluding CHI/C and PSI/(25) decay contribution to the prompt production cross section). RE = PBAR P --> J/PSI X.

Differential cross section for J/PSI's produced in CHI/C decays.

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