Avramenko, S.A.
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A Measurement of photon radiation in lepton pair events from Z0 decays

The OPAL collaboration Acton, P.D. ; Alexander, G. ; Allison, J. ; et al.
Phys.Lett.B 273 (1991) 338-354, 1991.
Inspire Record 319674 DOI 10.17182/hepdata.48520

We have measured the photon yield in lepton pair events recorded by the OPAL detector in a data sample corresponding to an integrated luminosity of 7.1 pb −1 at centre-of-mass energies between 88 GeV and 94 GeV. The results are compared to QED expectations for initial and final state photon radiation. No anomalous photon yield has been found, and stringent limits on the branching ratio for exotic radiative three body Z 0 decays into a photon and a pair of leptons are obtained. We also place limits on possible Z 0 decays into a photon and a resonance X with subsequent decays of X into a pair of leptons. Acollinear μ + μ − events with missing momentum along the beam direction are identified as events with hard initial state photon radiation and used to measure an average cross section of 15 ± 8 6 pb for e + e − annihilation into μ + μ − , in the so far untested range of centre-of-mass energies between 60 GeV and 84 GeV. This value is consistent with a cross section of 24 pb, expected from Z 0 and photon exchange.

1 data table
Table 1

No description provided.


A Study of multi - jet events at the CERN anti-p p collider and a search for double parton scattering

The UA2 collaboration Alitti, J. ; Ambrosini, G. ; Ansari, R. ; et al.
Phys.Lett.B 268 (1991) 145-154, 1991.
Inspire Record 317817 DOI 10.17182/hepdata.29361

A study of events containing at least four high transverse momentum jets and a search for double parton scattering (DPS) have been performed using data collected with the UA2 detector at the CERN p p Collider (√ s =630 GeV). The results are in good agreement with leading order QCD calculations. A value of σ DPS <0.82 nb at 95% confidence level (CL) is obtained for the DPS cross section.

3 data tables
Table 1

Data requested from authors.

Table 2

Uncorrected cross sections.

Table 3

Upper limit to DPS contribution to 4JET production.


A Direct observation of quark - gluon jet differences at LEP

The OPAL collaboration Alexander, G. ; Allison, J. ; Allport, P.P. ; et al.
Phys.Lett.B 265 (1991) 462-474, 1991.
Inspire Record 316872 DOI 10.17182/hepdata.48454

Quark and gluon jets in e + e − three-jet events at LEP are identified using lepton tagging of quark jets, through observation of semi-leptonic charm and bottom quark decays. Events with a symmetry under transposition of the energies and directions of a quark and gluon jet are selected: these quark and gluon jets have essentially the same energy and event environment and as a consequence their properties can be compared directly. The energy of the jets which are studied is about 24.5 GeV. In the cores of the jets, gluon jets are found to yield a softer particle energy spectrum than quark jets. Gluon jets are observed to be broader than quark jets, as seen from the shape of their particle momentum spectra both in and out of the three-jet event plane. The greater width of gluon jets relative to quark jets is also visible from the shapes of their multiplicity distributions. Little difference is observed, however, between the mean value of particle multiplicity for the two jet types.

1 data table
Table 1

QUARK means QUARK or QUARKBAR.


Measurement of three jet distributions sensitive to the gluon spin in e+ e- annihilations at S**(1/2) = 91-GeV

The OPAL collaboration Alexander, G. ; Allison, John ; Allport, P.P. ; et al.
Z.Phys.C 52 (1991) 543-550, 1991.
Inspire Record 317142 DOI 10.17182/hepdata.14852

None

4 data tables
Table 1

Data at Parton level.

Table 2

Ratio data/(Monte Carlo) at Parton level.

Table 3

Data at Parton level.. Distribution of Ellis-Karliner angle.

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A Study of K0(s) production in Z0 decays

The OPAL collaboration Alexander, G. ; Allison, J. ; Allport, P.P. ; et al.
Phys.Lett.B 264 (1991) 467-475, 1991.
Inspire Record 316151 DOI 10.17182/hepdata.29375

The production of K 0 mesons in e + e − interactions at center of mass energies in the region of the Z 0 mass has been investigated with the OPAL detector at LEP. The rate is found to be 2.10±0.02±0.14 K 0 , Z 0 per hadronic event. The predictions from the JETSET and HERWIG generators agree very well with both the rate and the scale invariant cross section (1/σ had β) (dσ/d x E ) for K 0 production. Comparisons of the inclusive momentum spectrum with predictions of an analytical QCD formula and with data from lower center of mass energies are presented.

3 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

K0 multiplicity per hadronic event.


Topological characteristics of the charge exchange reaction H-3 ---> He-3 on neon and magnesium nuclei at 9-GeV/c

Avramenko, S.A. ; Aksinenko, V.D. ; Anikina, M.Kh. ; et al.
JINR-P1-91-240, 1991.
Inspire Record 319449 DOI 10.17182/hepdata.38713

None

2 data tables
Table 1

No description provided.

Table 2

No description provided.


Cross-sections of the H-3 ---> He-3 reaction on hydrogen, carbon, aluminum, copper and lead at 9-gev/c

Avramenko, S.A. ; Belikov, Yu.A. ; Galperin, A.G. ; et al.
JINR-P1-91-239, 1991.
Inspire Record 319463 DOI 10.17182/hepdata.38697

None

1 data table
Table 1

Axis error includes +- 0.0/0.0 contribution (?////).


Charge exchange Li-7 ---> Be-7 cross-sections at 21-GeV/c on H, C, Al, Cu, Pb nuclei

Avramenko, S.A. ; Belikov, Yu.A. ; Golokhvastov, A.I. ; et al.
JINR-P1-91-206, 1991.
Inspire Record 319270 DOI 10.17182/hepdata.38715

None

1 data table
Table 1

CHARGE EXCHANGE INCLUSIVE CROSS SECTION.


Central Mg + Mg collisions with Lambda production at a momentum of 4.3-GeV/c per nucleon

Avramenko, S.A. ; Abdurakhimov, A.U. ; Aksinenko, V.D. ; et al.
Sov.J.Nucl.Phys. 55 (1992) 400-407, 1992.
Inspire Record 319240 DOI 10.17182/hepdata.38716

None

2 data tables
Table 1

CENTRAL COLLISIONS.

Table 2

CENTRAL COLLISIONS.


A Measurement of the electroweak couplings of up and down type quarks using final state photons in hadronic z0 decays

The OPAL collaboration Alexander, G. ; Allison, J. ; Allport, P.P. ; et al.
Phys.Lett.B 264 (1991) 219-232, 1991.
Inspire Record 316154 DOI 10.17182/hepdata.48516

The production rate of final state photons in hadronic Z 0 decays is measured as a function of y cut = M ij 2 / E cm 2 the jet resolution parameter and minimum mass of the photon-jet system. Good agreement with the theoretical expectation from an O( αα s ) matrix element calculation is observed. Comparing the measurement and the prediction for y cut = 0.06, where the experimental systematic and statistical errors and the theoretical uncertainties are small, and combining this measurement with our result for the hadronic width of the Z 0 , we derived partial widths of up and down type quarks to be Γ u = 333 ± 55 ± 72 MeV and Γ d = 358 ± 37 ± 48 MeV in agreement with the standard model expectations. We compare our yield with the QCD shower models including photon radiation. At low γ cut JETSET underestimates the photon yield, and ARIADNE describes the production rate well.

2 data tables
Table 1

It is assumed that the couplings of various up quarks to be the same.

Table 2

It is assumed that the couplings of various down type quarks to be the same.