HEPData Search

During the LEP running periods in 1990 and 1991 DELPHI has accumulated approximately 450 000 Z 0 decays into hadrons and charged leptons. The increased event statistics coupled with improved analysis techniques and improved knowledge of the LEP beam energies permit significantly better measurements of the mass and width of the Z 0 resonance. Model independent fits to the cross sections and leptonic forward- backward asymmetries yield the following Z 0 parameters: the mass and total width M Z = 91.187 ± 0.009 GeV, Γ Z = 2.486 ± 0.012 GeV, the hadronicf and leptonic partials widths Γ had = 1.725 ± 0.012 GeV, Γ ℓ = 83.01 ± 0.52 MeV, the invisible width Γ inv = 512 ± 10 MeV, the ratio of hadronic to leptonic partial widths R ℓ = 20.78 ± 0.15, and the Born level hadronic peak cross section σ 0 = 40.90 ± 0.28 nb. Using these results and the value of α s determined from DELPHI data, the number of light neutrino species is determined to be 3.08 ± 0.05. The individual leptonic widths are found to be: Γ e = 82.93 ± 0.70 MeV, Γ μ = 83.20 ± 1.11 MeV and Γ τ = 82.89 ± 1.31 MeV. Using the measured leptonic forward-backward asymmetries and assuming lepton universality, the squared vector and axial-vector couplings of the Z 0 to charged leptons are found to be g V ℓ 2 = (1.47 ± 0.51) × 10 −3 and g A ℓ 2 = 0.2483 ± 0.0016. A full Standard Model fit to the data yields a value of the top mass m t = 115 −82 +52 (expt.) −24 +52 (Higgs) GeV, corresponding to a value of the weak mixing angle sin 2 θ eff lept = 0.2339±0.0015 (expt.) −0.0004 +0.0001 (Higgs). Values are obtained for the variables S and T , or ϵ 1 and ϵ 3 which parameterize electroweak loop effects.

26 data tables match query

Table 1

Hadronic cross sections from the 1990 data set. Additional systematic uncertainties come from efficiencies and background of 0.4 pct in addition to the luminosity uncertainty 0.7 pct.

Table 2

Hadronic cross sections from the 1991 data set. Additional systematic uncertainties come from efficiencies and background of 0.2 pct in addition to the luminosity uncertainty 0.6 pct.

Table 3

E+ E- cross sections from the 1990 data set for both final state fermions in the polar angle range 44 to 136 degrees and accollinearity < 10 degrees (the s + t data).

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Search for solutions of the phase-shift analysis of pp interactions at 970 MeV

Vovchenko, V.G. ; Grebenyuk, O.G. ; Fedorov, O.Ya. ;

Yad.Fiz. 44 (1986) 456-459, 1986.

Inspire Record 239695 DOI 10.17182/hepdata.38007

A random search for solutions of the phase-shift analysis of pp scattering at 970 MeV is carried out. Solutions were selected according to the correct position of the zero of trajectory I of the Barrelet amplitude f1 in addition to the statistical criteria. Two pairs of solutions with similar phase shifts are found as a result. Two of these solutions have been found before

4 data tables match query

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Determination of Z0 resonance parameters and couplings from its hadronic and leptonic decays

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

Nucl.Phys.B 367 (1991) 511-574, 1991.

Inspire Record 317493 DOI 10.17182/hepdata.33016

From measurements of the cross sections for e + e − → hadrons and the cross sections and forward-backward charge-asymmetries for e e −→ e + e − , μ + μ − and π + π − at several centre-of-mass energies around the Z 0 pole with the DELPHI apparatus, using approximately 150 000 hadronic and leptonic events from 1989 and 1990, one determines the following Z 0 parameters: the mass and total width M Z = 91.177 ± 0.022 GeV, Γ Z = 2.465 ± 0.020 GeV , the hadronic and leptonic partial widths Γ h = 1.726 ± 0.019 GeV, Γ l = 83.4 ± 0.8 MeV, the invisible width Γ inv = 488 ± 17 MeV, the ratio of hadronic over leptonic partial widths R Z = 20.70 ± 0.29 and the Born level hadronic peak cross section σ 0 = 41.84±0.45 nb. A flavour-independent measurement of the leptonic cross section gives very consistent results to those presented above ( Γ l = 83.7 ± 0.8 rmMeV ). From these results the number of light neutrino species is determined to be N v = 2.94 ±0.10. The individual leptonic widths obtained are: Γ e = 82.4±_1.2 MeV, Γ u = 86.9±2.1 MeV and Γ τ = 82.7 ± 2.4 MeV. Assuming universality, the squared vector and axial-vector couplings of the Z 0 to charged leptons are: V ̄ l 2 = 0.0003±0.0010 and A ̄ l 2 = 0.2508±0.0027 . These values correspond to the electroweak parameters: ϱ eff = 1.003 ± 0.011 and sin 2 θ W eff = 0.241 ± 0.009. Within the Minimal Standard Model (MSM), the results can be expressed in terms of a single parameter: sin 2 θ W M ̄ S = 0.2338 ± 0.0027 . All these values are in good agreement with the predictions of the MSM. Fits yield 43< m top < 215 GeV at the 95% level. Finally, the measured values of Γ Z and Γ inv are used to derived lower mass bounds for possible new particles.

18 data tables match query

Table 1

Cross section from analysis I based on energy of charged particles. Additional 1.0 pct normalisation uncertainty.

Table 2

Cross section from analysis II based on calorimeter energies. Additional 1.1 pct normalisation uncertainty.

Table 3

Cross sections within the polar angle range 44 < THETA < 136 degrees and acollinearity < 10 degrees.. Overall systematic error 1.2 pct not included.

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Study of the Leptonic Decays of the $Z^0$ Boson

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

Phys.Lett.B 241 (1990) 425-434, 1990.

Inspire Record 295500 DOI 10.17182/hepdata.15431

Measurements are presented of the cross section ratios R ℓ = σ ℓ ( e + e − →ℓ + ℓ − ) σ h ( e + e − →hadrons) for ℓ=e, μ and τ using data taken from a scan around the Z 0 . The results are R e =(5.09± o .32±0.18)%, R μ =(0.46±0.35±0.17)% and R τ =(4.72±0.38±0.29)% where, for the ratio R e , the t -channel contribution has been subtracted. These results are consistent with the hypothesis of lepton universality and test this hypothesis at the energy scale s ∼8300 GeV 2 . The absolute cross sections σ ℓ (e + e − →ℓ + ℓ − ) have also been measured. From the cross sections the leptonic partial widths Γ e =(83.2±3.0±2.4) MeV, (Γ e Γ μ ) 1 2 =(84.6±3.0±2.4) MeV and (Γ e Γ τ ) 1 2 =(82.6±3.3±3.2) MeV have been extracted. Assuming lepton universality the ratio Γ ℓ Γ h =(4.89±0.20±0.12) × 10 −2 w was obtained, together with Γ ℓ =(83.6±1.8±2.2) MeV. The number of light neutrino species is determined to be N v =3.12±0.24±0.25. Al the data are consistent with the predictions of the standard model.

4 data tables match query

Table 1

E+ E- final state is t-channel subtracted.

Table 2

No t-channel subtraction. Statistical errors only.

Table 3

Statistical errors only.

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Elastic Scattering of 240-330 MeV π- Mesons by Hydrogen

Zinov, V.G. ; Korenchenko, S.M. ;

Sov.Phys.JETP 11 (1960) 794, 1960.

Inspire Record 1407580 DOI 10.17182/hepdata.70214

Results of measurements of differential cross sections for the elastic scattering of 11'- mesons of energies 240, 270, 307 and 333 Mev by hydrogen are given.

4 data tables match query

Table 1

No description provided.

Table 2

No description provided.

Table 3

No description provided.

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Elastic scattering of low energy photons by protons and electromagnetic polarizability of proton

Baranov, P.S. ; Buinov, G.M. ; Godin, V.G. ; et al.

Pisma Zh.Eksp.Teor.Fiz. 19 (1974) 777-780, 1974.

Inspire Record 96876 DOI 10.17182/hepdata.70437

None

2 data tables match query

Table 1

Axis error includes +- 0.0/0.0 contribution (?////UNCERTAINTY IN DATA PROCESSING).

Table 2

Axis error includes +- 0.0/0.0 contribution (?////UNCERTAINTY IN DATA PROCESSING).

Energy dependence of the spin-spin correlation parameter $C_{NN}$ at 50° and 90° c.m. for pp-elastic scattering in the energy range 0.69–0.95 GeV

Efimovyh, V.A. ; Kovalev, A.I. ; Poljakov, V.V. ; et al.

Phys.Lett.B 99 (1981) 28-32, 1981.

Inspire Record 1389635 DOI 10.17182/hepdata.27135

The spin-spin correlation parameter C NN at 50° and 90° c.m. for elastic pp-scattering has been obtained in the energy range 0.69–0.95 GeV. It was found that the parameter C NN (90°) shows resonance-like structure at energies near 700 MeV. Its energy dependence does not agree with Hoshizaki's phase-shift analysis predictions. C NN (50°) agrees well with these predictions and does not show any structure within the accuracy of the measurements.

1 data table match query

Table 1

No description provided.