HEPData Search

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Production of multistrange baryons and anti-baryons in sulphur - tungsten interactions at 200-GeV/c per nucleon

The WA85 collaboration Abatzis, S. ; Antinori, F. ; Barnes, R.P. ; et al.

Phys.Lett.B 259 (1991) 508-510, 1991.

Inspire Record 300857 DOI 10.17182/hepdata.29452

Production of Ξ − and Ξ − has been observed for the first time in heavy ion interactions by the WA85 Experiment. Multistrange baryon and antibaryon production is expected to be a useful probe in the search for quark-gluon plasma formation. We describe the procedure used to select these cascade candidates and show that Ξ − and Ξ − decays can be identified. The ratio of Ξ Ξ production, corrected for geometrical acceptances and reconstruction efficiencies, is 0.39 ± 0.07 for sulphur-tungsten interactions in the central rapidity interval 2.3< Y lab <3.0 and p T >1.1 GeV/ c .

1 data table

Table 1

No description provided.

rivet Analysis
Charged particle multiplicity distributions in Z0 hadronic decays

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.

Z.Phys.C 50 (1991) 185-194, 1991.

Inspire Record 301657 DOI 10.17182/hepdata.15028

This paper presents an analysis of the multiplicity distributions of charged particles produced inZ0 hadronic decays in the DELPHI detector. It is based on a sample of 25364 events. The average multiplicity is =20.71±0.04(stat)±0.77(syst) and the dispersionD=6.28±0.03(stat)±0.43(syst). The data are compared with the results at lower energies and with the predictions of phenomenological models. The Lund parton shower model describes the data reasonably well. The multiplicity distributions show approximate KNO-scaling. They also show positive forward-backward correlations that are strongest in the central region of rapidity and for particles of opposite charge.

5 data tables

Table 1

Charged particle multiplicity distribution for the raw data in full phase space.

Table 2

Charged particle multiplicity distribution for full phase space. Errors include systematics. A 2 pct correction for excess electrons from photon conversions is not included. The first two points, at N=2 and 4, were not measured but taken from the Lund PS model.

Table 3

Charged particle multiplicity distribution for single hemisphere. Errors include systematics. A 2 pct correction for excess electrons from photon conversions is not included.

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Experimental study of the triple gluon vertex

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adami, F. ; et al.

Phys.Lett.B 255 (1991) 466-476, 1991.

Inspire Record 301659 DOI 10.17182/hepdata.48514

In four-jet events from e + e − →Z 0 →multihadrons one can separate the three principal contributions from the triple-gluon vertex, double gluon-bremsstrahlung and the secondary quark-antiquark production, using the shape of the two-dimensional angular distributions in the generalized Nachtmann-Reiter angle θ NR ∗ and the opening angle of the secondary jets. Thus one can identify directly the contribution from the triple-gluon vertex without comparison with a specific non-QCD model. Applying this new method to events taken with the DELPHI-detector we get for the ratio of the colour factor N c to the fermionic Casimir operator C F : N c C F = 2.55 ± 0.55 ( stat. ) ± 0.4 ( fragm. + models ) ± 0.2 ( error in bias ) in agreement with the value 2.25 expected in QCD from N c =3 and C F = 4 3 .

1 data table

Table 1

NC, CF, and TR are the color factors for SU(3) group.

rivet Analysis
Two photon production of pion pairs

Boyer, J. ; Butler, F. ; Gidal, G. ; et al.

Phys.Rev.D 42 (1990) 1350-1367, 1990.

Inspire Record 304882 DOI 10.17182/hepdata.22881

We present a new high-statistics measurement of the cross section for the process e+e−→e+e−π+π− at a center-of-mass energy of 29 GeV for invariant pion-pair masses M(π+π−) between 350 MeV/c2 and 1.6 GeV/c2. We observe the f2(1270) and measure its radiative width to be 3.15±0.04±0.39 keV. We also observe an enhancement in the π+π− spectrum near 1 GeV. General agreement is found with unitarized models of the γγ→π+π− reaction that include final-state interactions.

2 data tables

Table 1

No description provided.

Table 2

Statistical errors only.

Charge exchange photoproduction of the a2- (1320) in association with Delta++ at 19.3-GeV/c

The SLAC Hybrid Facility Photon collaboration Condo, G.T. ; Handler, T. ; Shimony, J. ; et al.

Phys.Rev.D 41 (1990) 3317-3323, 1990.

Inspire Record 306086 DOI 10.17182/hepdata.22925

We examine the negative 3π final state produced in association with Δ++(1232) in the reaction γp→Δ++π+π−π− at an incident photon energy of 19.3 GeV. The most prominent enhancement in the 3π spectrum occurs at a mass and with a width consistent with the parameters of the a2(1320). This identification is confirmed by the various angular distributions. The a2 production cross section, corrected for efficiencies and alternate a2 decay modes, is 0.45±0.05 μb.

1 data table

Table 1

No description provided.

rivet Analysis
Measurement of the decay of the Upsilon (1S) and Upsilon (2S) resonances to muon pairs

The Crystal Ball collaboration Kobel, M. ; Antreasyan, D. ; Bartels, H.W. ; et al.

Z.Phys.C 53 (1992) 193-206, 1992.

Inspire Record 306832 DOI 10.17182/hepdata.14771

Using the Crystal Ball detector at thee+e− storage ring DORIS II, we have measured the branching fraction to muon pairsBμμ of the Υ(

2 data tables

Table 1

Corrected cross section. Statistical and point to point systematic errors combined. Additional systematic error given above. The storage ring SQRT(S) has a 7.9 +- 0.2 MeV energy spread around the values given.

Table 2

Corrected cross section. Statistical and point to point systematic errors combined. Additional systematic error given above.The storage ring SQRT(S) has a 8.2 +- 0.3 MeV energy spread around the values given.

A measurement of the Z0 invisible width by single photon counting.

The OPAL collaboration Akrawy, M.Z. ; Alexander, G. ; Allison, John ; et al.

Z.Phys.C 50 (1991) 373-384, 1991.

Inspire Record 302586 DOI 10.17182/hepdata.14980

The OPAL detector at LEP is used to measure the branching ratio of theZ0 into invisible particles by measuring the cross section of single photon events ine+e− collisions at centre-of-mass energies near theZ0 resonance. In a data sample of 5.3 pb−1, we observe 73 events with single photons depositing more than 1.5 GeV in the electromagnetic calorimeter, with an expected background of 8±2 events not associated with invisibleZ0 decay. With this data we determine theZ0 invisible width to be 0.50±0.07±0.03 GeV, where the first error is statistical and the second systematic. This corresponds to 3.0±0.4±0.2 light neutrino generations in the Standard Model.

1 data table

Table 1

No description provided.

A Search for weakly interacting neutral particles in missing energy events in 450-GeV/c p N collisions

The HELIOS collaboration Åkesson, T. ; Almehed, S. ; Angelis, A.L. S. ; et al.

Z.Phys.C 52 (1991) 219-226, 1991.

Inspire Record 302922 DOI 10.17182/hepdata.15014

We have measured the inclusive cross-section as a function of missing energy, due to the production of neutrinos or new weakly interacting neutral particles in 450 GeV/c proton-nucleus collisions, using calorimetric measurements of visible event energy. Upper limits are placed on the production of new particles as a function of their energy. These upper limits are typically an order

9 data tables

Table 1

Differential single diffraction cross section.

Table 2

Differential single diffraction cross section.

Table 3

Differential single diffraction cross section.