HEPData Search

Showing 10 of 49 results

Measurement of the fraction of hadronic Z decays into charm quark pairs.

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.

Eur.Phys.J.C 4 (1998) 557-570, 1998.

Inspire Record 468852 DOI 10.17182/hepdata.49530

The full statistics of hadronic Z decays collected with the ALEPH detector are analysed to measure, by three methods, the ratio, ${\rm R_c}$ , of the partial decay

1 data table

Table 1

No description provided.

rivet Analysis
Inclusive Sigma- and Lambda(1520) production in hadronic Z decays.

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

Phys.Lett.B 475 (2000) 429-447, 2000.

Inspire Record 524694 DOI 10.17182/hepdata.49984

Production of Sigma- and Lambda(1520) in hadronic Z decays has been measured using the DELPHI detector at LEP. The Sigma- is directly reconstructed as a charged track in the DELPHI microvertex detector and is identified by its Sigma -> n pi decay leading to a kink between the Sigma- and pi-track. The reconstruction of the Lambda(1520) resonance relies strongly on the particle identification capabilities of the barrel Ring Imaging Cherenkov detector and on the ionisation loss measurement of the TPC. Inclusive production spectra are measured for both particles. The production rates are measured to be <N_{Sigma-}/N_{Z}^{had}> = 0.081 +/- 0.002 +/- 0.010, <N_{Lambda(1520)}/N_{Z}^{had}> = 0.029 +/- 0.005 +/- 0.005. The production rate of the Lambda(1520) suggests that a large fraction of the stable baryons descend from orbitally excited baryonic states. It is shown that the baryon production rates in Z decays follow a universal phenomenological law related to isospin, strangeness and mass of the particles.

4 data tables

Table 1

The measured differential cross section for SIGMA- production.

Table 2

The total production rate of SIGMA-. The second systematic (DSYS) error is due to the extrapolation to the fullx-range.

Table 3

The measured differential cross section for LAMBDA(1520) production. The first error is the fit error.

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rivet Analysis
Measurement of inclusive omega and eta' production in hadronic Z decays.

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

Phys.Lett.B 393 (1997) 465-476, 1997.

Inspire Record 427107 DOI 10.17182/hepdata.47618

We present a study of the inclusive ω and η′ production based on 3.1 million hadronic Z decays recorded with the L3 detector at LEP during 1991–1994. The production rates per hadronic Z decay have been measured to be 1.17±0.17 ω mesons and 0.25±0.04 η′ mesons. The production rates and the differential cross sections have been compared with predictions of the JETSET and the HERWIG Monte Carlo models. We have observed that the differential cross sections can be described by an analytical quantum chromodynamics calculation.

12 data tables

Table 1

Final production rates per hadronic Z0 decay.

Table 2

Corrected production rates from the omega --> pi+ pi- p0 decay mode. Extrapolation to full x range.

Table 3

Corrected production rates from the etaprime --> pi+ pi- eta decay mode. Extrapolation to full x range.

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rivet Analysis
Sigma+, Sigma0 and Sigma- hyperon production in hadronic Z0 decays.

The OPAL collaboration Alexander, G. ; Allison, John ; Altekamp, N. ; et al.

Z.Phys.C 73 (1997) 587-600, 1997.

Inspire Record 421977 DOI 10.17182/hepdata.47948

The production rates of the $J_{P}={1⩈er 2}^{+}$ octet Σ baryons in hadronic Z0 decays have been measured using the OPAL detector at LEP. The inclusive production rates per hadronic Z0 decay of the three isospin states (including the respective antiparticle) have been separately measured for the first time: $άtrix {n_{Sigma^{+}}=0.099pm 0.008pm 0.013ŗ n_{Sigma^{0}}=0.071pm 0.012pm 0.013ŗ n_{Sigma^{-}}=0.083pm 0.006pm 0.009ŗ}$ where the first error is statistical and the second is systematic. Differential cross-sections are also presented for the Σ+ and Σ− and compared with JETSET and HERWIG predictions. Assuming full isospin symmetry, the average inclusive rate is: ${1⩈er 3}[n_{Sigma^{+}+Sigma^{0}+Sigma^{-}}]=0.084pm 0.005 ({⤪ stat.}) pm 0.008 ({⤪ syst.})$.

5 data tables

Table 1

Differential cross section for SIGMA+ production.

Table 2

Differential cross section for SIGMA- production.

Table 3

No description provided.

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Production of SIGMA0 and OMEGA- in Z decays

The DELPHI collaboration Adam, W. ; Adye, T. ; Agasi, E. ; et al.

Z.Phys.C 70 (1996) 371-382, 1996.

Inspire Record 416098 DOI 10.17182/hepdata.47799

None

3 data tables

Table 1

Statistical error only.

Table 2

No description provided.

Table 3

No description provided.

rivet Analysis
Measurement of inclusive pi0 production in hadronic Z0 decays

The DELPHI collaboration Adam, W. ; Adye, T. ; Agasi, E. ; et al.

Z.Phys.C 69 (1996) 561-574, 1996.

Inspire Record 401100 DOI 10.17182/hepdata.48063

An analysis is presented of inclusive π0 production in Z0 decays measured with the DELPHI detector. At low energies, π0 decays are reconstructed by using pairs of converted photons and combinations of converted photons and photons reconstructed in the barrel electromagnetic calorimeter (HPC). At high energies (up to $x_p={2cdot p≪/{sqrt s}=0.75}$) the excellent granularity of the HPC is exploited to search for two-photon substructures in single showers. The inclusive differential cross section is measured as a function of energy for qq̅ and bb̅ events. The number of π0’s per hadronic Z0 event is $N(≪^0)/Z_{had} ^0=9.2pm 0.2({⤪ stat})pm 1.0 ({⤪ syst})$ and for bb̅ events the number of π0’s is ${⤪ N}(≪^0)/{⤪ b⋏r b}=10.1pm 0.4({⤪ stat})pm 1.1 ({⤪ syst})$. The ratio of the number of π0’s in bb̅ events to hadronic Z0 events is less affected by the systematic errors and is found to be 1.09 ±0.05 ±0.01. The measured π0 cross sections are compared with the predictions of different parton shower models. For hadronic events, the peak position in the $xi_{⤪ p}={⤪ ln}(1/{⤪ x_p})$ distribution is $xi_p^{⋆ar}=3.90_{-0.14}^{+0.24}.$ The average number of π0’s from the decay of primary B hadrons is found to be N(B → π0X)/B hadron = 2.78 ± 0.15(stat) ± 0.60(syst).

4 data tables

Table 1

Differential cross section for all events.

Table 2

Mean PI0 multiplicity extrapolated below 0.011 with JETSET 7.3.

Table 3

Differential cross section for the enriched (b bbar) data set.

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rivet Analysis
Measurement of Delta++ (1232) production in hadronic Z decays

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

Phys.Lett.B 361 (1995) 207-220, 1995.

Inspire Record 399737 DOI 10.17182/hepdata.48095

A measurement of the Δ ++ (1232) inclusive production in hadronic decays of the Z at LEP is presented, based on 1.3 million hadronic events collected by the DELPHI detector in the 1994 LEP running period. The DELPHI ring imaging Cherenkov counters are used for identifying hadrons. The average Δ ++ (1232) multiplicity per hadronic event is 0.079 ± 0.015 which is more than a factor of two below the JETSET, HERWIG and UCLA model predictions. It agrees with a recently proposed universal mass dependence of particle production rates in e + e − annihilations.

2 data tables

Table 1

Differential DELTA(1232)++ cross section. Errors are combined statistics and systematics.

Table 2

Mean multiplicities. Extrapolation to full x range using a combination of JETSET, HERWIG and UCLA models. The second systematic error comes from the uncertainty in the extrapolation.

Study of prompt photon production in hadronic Z0 decays

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

Z.Phys.C 69 (1995) 1-14, 1995.

Inspire Record 397391 DOI 10.17182/hepdata.48136

None

3 data tables

Table 1

Rates for gamma + 1 jet.

Table 2

Rates for gamma + 2 jet.

Table 3

Rates for gamma + 3 jet.

rivet Analysis
The Production of neutral kaons in Z0 decays and their Bose-Einstein correlations

The OPAL collaboration Akers, R. ; Alexander, G. ; Allison, John ; et al.

Z.Phys.C 67 (1995) 389-402, 1995.

Inspire Record 393503 DOI 10.17182/hepdata.48008

The production of neutral kaons in e+e− annihilation at centre-of-mass energies in the region of the Z0 mass and their Bose-Einstein correlations are investigated with the OPAL detector at LEP. A total of about 1.26×106 Z0 hadronic decay events are used in the analysis. The production rate of K0 mesons is found to be 1.99±0.01±0.04 per hadronic event, where the first error is statistical and the second systematic. Both the rate and the differential cross section for K0 production are compared to the predictions of Monte Carlo generators. This comparison indicates that the fragmentation is too soft in bothJetset andHerwig. Bose-Einstein correlations in Ks0Ks0 pairs are measured through the quantityQ, the four momentum difference of the pair. A threshold enhancement is observed in Ks0Ks0 pairs originating from a mixed sample of$K^0 \bar K^0$ and K0K0 ($\bar K^0 \bar K^0$) pairs. For the strength of the effect and for the radius of the emitting source we find values of λ=1.14±0.23±0.32 andR0=(0.76±0.10±0.11) fm respectively. The first error is statistical and the second systematic.

3 data tables

Table 1

No description provided.

Table 2

The mean x is computed using the method of Lafferty and Wyatt NIM A355(1995)541.

Table 3

The mean x is computed using the method of Lafferty and Wyatt NIM A355(1995)541.