Brady, F.P.
E+ E- --> JETS
E+ E- Scattering
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rivet Analysis
PHYSICS WITH HIGH-ENERGY ELECTRON POSITRON COLLIDING BEAMS WITH THE MARK-J DETECTOR

The MARK-J & AACHEN-DESY-MIT-NIKHEF-BEIJING collaborations Barber, D.P. ; Becker, U. ; Benda, H. ; et al.
Phys.Rept. 63 (1980) 337-391, 1980.
Inspire Record 158857 DOI 10.17182/hepdata.27618

This report reviews the experimental investigation of high energy e + e − interactions by the MARK J collaboration at PETRA, the electron-positron colliding beam accelerator at DESY in Hamburg, Germany. The physics objectives include studies of several purely electromagnetic processes and hadronic final states, which further our knowledge of the nature of the fundamental constituents and of their strong, electromagnetic and weak interactions. Before discussing the physics results, the main features and the principal components of the MARK J detector are discussed in terms of design, function, and performance. Several aspects of the on-line data collection and the off-line analysis are also outlined. Results are presented on tests of quantum electrodynamics using e + e − → e + e − , μ + μ − and τ + τ − , on the measurement of R , the ratio of the hadronic to the point-like muon pair cross section, on the search for new quark flavors, on the discovery of three jet events arising from the radiation of hard noncollinear gluons as predicted by quantum chromodynamics, and on the determination of the strong coupling constant α s .

4 data tables
Table 1

SUMMARY OF RESULTS FOR R FROM TOTAL OF 2595 HADRON EVENTS. INCLUDES RED = 1046, 1079, 1072 AND 1114.

Table 2

MEAN THRUST AND THRUST DISTRIBUTION (1/N)*DN/DTHRUST AT 13, 17, 22 AND 30 GEV. SOMEWHAT DETECTOR DEPENDENT. INCLUDES RED = 1079 AND 1072. SEE ALSO RED = 1114. ALSO JET ANALYSIS USING FOX-WOLFRAM MOMENTS.

Table 3

OBLATENESS DISTRIBUTION AT 17 AND 27.4 TO 31.6 GEV. SEE RED = 1146.

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Tests of Quantum Chromodynamics and a Direct Measurement of the Strong Coupling Constant $\alpha_S$ at $\sqrt{s}=30$-{GeV}

Barber, D.P. ; Becker, U. ; Benda, H. ; et al.
Phys.Lett.B 89 (1979) 139-144, 1979.
Inspire Record 143680 DOI 10.17182/hepdata.6483

We report the measurement of the reaction e + + e − → hadronic jets at a center-of-mass energy √ s =30 GeV using the MARK-J detector at PETRA. By measuring the energy and angular distribution of both neutrals and charged particles we were able to isolate unambiguously the three-jet events in a kinematic region where the backgrounds from q q and phase space contributions and other processes are small. Various comparisons of the data with quantum chromodynamics were made. The relative yield of three-jet events and the shape distribution of the events enable us to determine α s = 0.23 ± 0.02 (statistical error) with a systematic error of ± 0.04.

2 data tables
Table 1

OBLATENESS AND THRUST DISTRIBUTIONS FOR NARROW AND BROAD JETS AT 30 GEV. THESE DATA ARE SOMEWHAT ANALYSIS AND DETECTOR DEPENDENT.

Table 2

No description provided.


Discovery of Three Jet Events and a Test of Quantum Chromodynamics at PETRA Energies

Barber, D.P. ; Becker, U. ; Benda, H. ; et al.
Phys.Rev.Lett. 43 (1979) 830, 1979.
Inspire Record 142085 DOI 10.17182/hepdata.20742

We report the analysis of the spatial energy distribution of data for e+e−→hadrons obtained with the MARK-J detector at PETRA. We define the quantity "oblateness" to describe the flat shape of the energy configuration and the three-jet structure which is unambiguously observed for the first time. Our data can be explained by quantum chromodynamic predictions for the production of quark-antiquark pairs accompanied by hard noncollinear gluons.

1 data table
Table 1

AVERAGE OBLATENESS AS A FUNCTION OF SQRT(S) AND OF THRUST AND OBLATENESS DISTRIBUTION (1/N)*DN/DOBLATENESS AT 17 AND 27.4 TO 31.6 GEV. THESE DATA ARE RATHER DETECTOR DEPENDENT.