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Decay properties of tau leptons measured at the Z0 resonance

The L3 collaboration Adeva, B. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.

Phys.Lett.B 265 (1991) 451-461, 1991.

Inspire Record 318230 DOI 10.17182/hepdata.40873

From 2540 Z 0 → τ + τ − events, we determine the inclusive decay branching fractions of the τ -lepton into one and three charged particles to be 0.856 ± 0.006 (stat.) ± 0.003 (syst.) and 0.144 ± 0.006 (stat.) ± 0.003 (syst.), respectively. The leptonic branching fractions are measured to be 0.175 ± 0.008 (stat.) ± 0.005 (syst.) for τ → μν μ ντ and 0.177 ± 0.007 (stat.) ± 0.006 (syst.) for τ → eν e ν τ . We determined the τ lifetime both from three-prong decays using the decay length and from one-prong decays using the impact parameter. The results from the two independent methods agree and yield a combined value of [0.309 ± 0.023 (stat.) ± 0.030 (syst.)] × 10 −12 s.

1 data table

Table 1

ALPHAS extracted from the ratio of the branching fractions.

Measurement of the Omega- Magnetic Moment

Diehl, H.T. ; Teige, S. ; Thomson, G.B. ; et al.

Phys.Rev.Lett. 67 (1991) 804-807, 1991.

Inspire Record 317788 DOI 10.17182/hepdata.19879

A sample of 24 700 Ω− hyperons was produced by a prolarized neutral beam in a spin-transfer reaction. The Ω− polarizations are found to be -0.054±0.019 and -0.149±0.055 at mean Ω− momenta of 322 and 398 GeV/c, respectively. The directions of these polarizations give an Ω− magnetic moment of -(1.94±0.17±0.14)μN

1 data table

Table 1

No description provided.

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.

Intranuclear cascading at ultrahigh-energy in heavy ion interactions

Jain, P.L. ; Singh, G. ; Sengupta, K. ;

Z.Phys.C 52 (1991) 465-470, 1991.

Inspire Record 316804 DOI 10.17182/hepdata.14775

Intranuclear cascading mechanism one of the important non-linear effects in high energy nucleusnucleus collisions is investigated. The data on multiplicity (ns) and pseudorapidity (η) distributions of shower particles produced by32S and16O at 200A GeV,16O at 60A GeV,28Si at 14.5A GeV and He at ≈140A GeV are presented and compared with the string model VENUS, which takes into account the cascade interactions of secondary particles. The effect of the intranuclear collisions on the distributions of <η> versus is discussed for all the beams.

2 data tables

Table 1

No description provided.

Table 2

No description provided.

Improved measurements of electroweak parameters from Z decays into fermion pairs

The ALEPH collaboration Decamp, D. ; Deschizeaux, B. ; Goy, C. ; et al.

Z.Phys.C 53 (1992) 1-20, 1992.

Inspire Record 317141 DOI 10.17182/hepdata.14857

The properties of theZ resonance are measured on the basis of 190 000Z decays into fermion pairs collected with the ALEPH detector at LEP. Assuming lepton universality,Mz=(91.182±0.009exp±0.020L∶P) GeV,ГZ=(2484±17) MeV, σhad0=(41.44±0.36) nb, andГjad/Гℓℓ=21.00±0.20. The corresponding number of light neutrino species is 2.97±0.07. The forward-back-ward asymmetry in leptonic decays is used to determine the ratio of vector to axial-vector coupling constants of leptons:gv2(MZ2)/gA2(MZ2)=0.0072±0.0027. Combining these results with ALEPH results on quark charge and\(b\bar b\) asymmetries, and τ polarization, sin2θW(MZ2). In the contex of the Minimal Standard Model, limits are placed on the top-quark mass.

7 data tables

Table 1

Statistical errors only.

Table 2

No description provided.

Table 3

No description provided.

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Xi-, anti-xi-, Lambda and anti-Lambda production 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 270 (1991) 123-127, 1991.

Inspire Record 318147 DOI 10.17182/hepdata.29306

Multi-strange baryon and antibaryon production is expected to be a useful probe in the search for quark-gluon plasma formation. We present the transverse mass distributions of negative particles, Λ' s , Λ ' s and Ξ − ' s produced in sulphur-tungsten interactions at 200 GeV/ c per nucleon and give the corrected rations Λ /Λ, Ξ − /Λ and Ξ − / Λ . Our ratio Ξ − / Λ appears to be larger than that from pp interactions.

3 data tables

Table 1

Inverse slopes for different particle production.

Table 2

Data from this and other WA85 publications.

Table 3

Data from this and other WA85 publications.

The reaction e+ e- ---> gamma gamma (gamma) at Z0 energies

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

Phys.Lett.B 268 (1991) 296-304, 1991.

Inspire Record 317825 DOI 10.17182/hepdata.29352

The total and differential cross-sections for the reaction e + e − → γγ ( γ ) are measured at centre of mass energies around 91 GeV using an integrated luminosity of 4.7 pb −1 . The aggreement with QED prediction is good. Consequently there is no evidence for non-standard channels which would have the same experimental signature. The lower limits on the QED cuttoff parameters are Λ + > 113 GeV and Λ − > 95 GeV. An upper limit on the effective coupling between a possible excited electron and the gamma is derived. At 95% confidence level the branching ratios for Z 0 decay into π 0 γ, ηψ and γγγ are below 1.5 × 10 −4 , 2.8 × 10 −4 and 1.4 × 10 −4 respectively.

2 data tables

Table 1

Radiative effects are subtracted.

Table 2

Radiative effects subtracted.

Measurement of the Z (p(T)) distribution in anti-p p collisions at s**(1/2) = 1.8-TeV

The CDF collaboration Abe, F. ; Amidei, Dante E. ; Apollinari, G. ; et al.

Phys.Rev.Lett. 67 (1991) 2937-2941, 1991.

Inspire Record 322634 DOI 10.17182/hepdata.19888

We have measured the Z-boson production differential cross section as a function of transverse momentum using Z→ee and Z→μμ decays in p¯p collision at √s =1.8 TeV with the Collider Detector at Fermilab. Comparison with standard-model predictions shows good agreement over the range 0

1 data table

Table 1

Errors are systematic and statistical combined, and are correlated bin to bin due to the correction for resolution smearing.