HEPData Search

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Properties of Hadronic Events in e$^{+} $e$^{-}$ Annihilation at $S^{(1/2)}=91$-{GeV}

The ALEPH collaboration Decamp, D. ; Deschizeaux, B. ; Lees, J.P. ; et al.

Phys.Lett.B 234 (1990) 209-218, 1990.

Inspire Record 283354 DOI 10.17182/hepdata.29739

We report on properties of hadronic events from e + e − annihilation observed by the ALEPH detector at the large Electron Positron Collider at CERN. The center-of-mass energy was s =91.0−91.3 GeV . Measured distributions of the global event-shape variables sphericity, aplanarity, thrust and minor value, and of the inclusive variables x p , p ⊥ in , p ⊥ out and y are presented. We measure a mean charged multiplicity in hadronic events of 〈 N ch 〉=21.3±0.1 (statistical)±0.6 (systematic). The data are in good agreement with QCD-based models which use the leading-logarithm approximation, and are less well described by a model using O( α s 2 ) QCD.

1 data table

Table 1

NO RAD. CORR APPLIED.

Determination of the Number of Light Neutrino Species

The ALEPH collaboration Decamp, D. ; Deschizeaux, B. ; Lees, J.P. ; et al.

Phys.Lett.B 231 (1989) 519-529, 1989.

Inspire Record 282904 DOI 10.17182/hepdata.29758

The cross-section for e + e − → hadrons in the vicinity of the Z boson peak has been measured with the ALEPH detector at the CERN Large Electron Positron collider, LEP. Measurements of the Z mass, M z = (91.174±0.070) GeV, the Z width Γ z =(2.68±0.15) GeV, and of the peak hadronic cross-section, σ had peak =(29.3±1.2) nb, are presented. With the constraints of the standard electroweak model, the number of light neutrino species is found to be N v =3.27±0.30. this results rules out of the possibility of a fourth type of light neutrino at 98% CL.

2 data tables

Table 1

Selection from TPC tracks.

Table 2

Selection by calorimeters.

Search for Narrow Baryonia With Negative and Positive Strangeness

The BIS-2 collaboration Aleev, A.N. ; Arefev, V.A. ; Balandin, V.P. ; et al.

Z.Phys.C 47 (1990) 533-537, 1990.

Inspire Record 285796 DOI 10.17182/hepdata.15148

A search for baryonia with negative and positive strangeness decaying respectively into$\Lambda+ \bar p + pions$ and$\bar \Lambda+ p + pions$ has been carried out in a neutron beam with a mean momentum of ≅40 GeV/c in an experiment performed at the Serpukhov accelerator. There is a strong indication of the existence of these baryonia. The following four charge states are observed for negative and positive strangeness: neutral, negative, positive and doubly charged. Their mean mass is 3055±25 MeV/c2 and the width Γ≦36±15 MeV/c2. The data show that the isotopic spin of the baryonia is ≧3/2. The baryonia production cross sections in the acceptable kinematic regionXF≧0.2 andPT≦1 GeV/c times the branching ratios of the observed decays are of the order of 1 μb per nucleon.

1 data table

Table 1

No description provided.

High Transverse Momentum $\eta$ Production in $\pi^- p$, $\pi^+ p$ and $p p$ Interactions at 280-{GeV}/$c$

The WA70 collaboration Bonesini, M. ; Bonvin, E. ; Booth, P.S. L. ; et al.

Z.Phys.C 42 (1989) 527, 1989.

Inspire Record 267856 DOI 10.17182/hepdata.15526

The inclusive cross sections for η production by the interactions of 280 GeV/c momentum π−, π+, and proton beams in hydrogen have been measured. The kinematical range covered is −0.45<xF<0.45, and 4.0<PT<7.0 GeV/c for FeynmanxF and transverse momentum respectively. The η to π0 cross section ratios are given for the three reactions. The ratio of π−p to π+p cross sections for η production in the above kinematic ranges is 1.22±0.08±0.11.

3 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

Study of Neutral Strange Particle Production in $p p$ Interactions at 32-{GeV}/$c$ and Comparison With $\bar{p} p$ Data

Bogolyubsky, M.Yu. ; Bumazhnov, V.A. ; Kiryunin, A.E. ; et al.

Sov.J.Nucl.Phys. 50 (1989) 424, 1989.

Inspire Record 269294 DOI 10.17182/hepdata.10310

None

15 data tables

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Studies of Intermediate Vector Boson Production and Decay in {UA1} at the {CERN} Proton - Antiproton Collider

The UA1 collaboration Albajar, C. ; Albrow, M.G. ; Allkofer, O.C. ; et al.

Z.Phys.C 44 (1989) 15-61, 1989.

Inspire Record 267170 DOI 10.17182/hepdata.15015

An extensive study of production and decay properties of charged and neutral Intermediate Vector Bosons (IVB) at the CERN proton-antiproton collider is presented. Intermediate Vector Bosons were detected in the electron, muon, and tau decay modes at centre-of-mass energies of 0.546 and 0.630 TeV. This paper is a summary, based on all the available data from the UA1 experiment from the running periods 1982–1985. Results are presented and compared with expectations of the Standard Eletroweak Model and QCD-improved Drell-Yan annihilation processes. The general conclusion is that there is an excellent agreement between the predictions of the Standard Model and our measurements.

5 data tables

Table 1

No description provided.

Table 2

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Table 3

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DOUBLE PROMPT PHOTON PRODUCTION AT HIGH TRANSVERSE MOMENTUM BY pi- ON PROTONS AT 280-GeV/c

The WA70 collaboration Bonvin, E. ; Bopp, R. ; Carroll, L.J. ; et al.

Z.Phys.C 41 (1989) 591, 1989.

Inspire Record 265091 DOI 10.17182/hepdata.15470

A search for pairs of highpT prompt photons produced in hydrogen by a 280 GeV/c incidentπ- beam has been carried out using a fine-grained electromagnetic calorimeter and the Omega spectrometer at the CERN SPS. Clear evidence for the existence of such events is found with a six standard deviation signal forpT>3.0 GeV/c. The cross-sections are consistent with beyond leading order QCD calculations. A discussion on the determination of αs is also presented.

2 data tables

Table 1

PT is the transverse momentum of either of the two photons.

Table 2

PT is the transverse momentum of either of the two photons.