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

Differential cross section for all events.

Mean PI0 multiplicity extrapolated below 0.011 with JETSET 7.3.

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

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Production of charged particles, K0(s), K+-, p and Lambda in Z --> b anti-b events and in the decay of b hadrons

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 347 (1995) 447-466, 1995.
Inspire Record 392257 DOI 10.17182/hepdata.48180

A sample of events enriched in bb̄ quark pairs was selected in the data recorded by the DELPHI experiment at LEP during 1992 and 1993, by the presence of secondary decay vertices from short-lived particles. Using this sample, the average multiplicities of K s 0 , K ± , p(p̄), Λ( Λ ) and of charged particles in bb̄ events have been measured, distinguishing the component from fragmentation and the component coming from the decay of b-hadrons. The measurement of the average charge multiplicity in bb̄ events was used to compute the mean fractional beam energy carried by the primary b-hadron, and the difference in charged particle multiplicity between bb̄ events and light quark (uū, dd̄, ss̄) events.

9 data tables

Event multiplicity in bottom events.

Differential cross section for charged particles in BOTTOM tagged hemispheres.

Differential cross section for charged particles in untagged hemispheres.

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Measurements of cross-section and asymmetry for e+ e- ---> b anti-b and heavy quark fragmentation at KEK TRISTAN

The AMY collaboration Liu, F. ; Chinitz, L.M. ; Abe, K. ; et al.
Phys.Rev.D 49 (1994) 4339-4347, 1994.
Inspire Record 381324 DOI 10.17182/hepdata.22547

Using 773 muons found in hadronic events from 142 pb−1 of data at a c.m. energy of 57.8 GeV, we extract the cross section and forward-backward charge asymmetry for the e+e−→bb¯ process, and the heavy quark fragmentation function parameters for the Peterson model. For the analysis of the e+e−→bb¯ process, we use a method in which the behavior of the c quark and lighter quarks is assumed, with only that of the b quark left indeterminate. The cross section and asymmetry for e+e−→bb¯ are found to be Rb = 0.57 ± 0.06(stat) ± 0.08(syst) and Ab = −0.59 ± 0.09 ± 0.09, respectively. They are consistent with the standard model predictions. For the study of the fragmentation function we use the variable 〈xE〉, the fraction of the beam energy carried by the heavy hadrons. We obtain 〈xE〉c=0.56−0.05−0.03+0.04+0.03 and 〈xE〉b=0.65−0.04−0.06+0.06+0.05, respectively. These are in good agreement with previously measured values.

4 data tables

No description provided.

No description provided.

Here X=E(hadron)/E(beam).

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A Study of the charm and bottom quark production in e+ e- annihilation at s**(1/2) = 58-GeV using prompt electrons

The VENUS collaboration Abe, K. ; Amako, K. ; Arai, Y. ; et al.
Phys.Lett.B 313 (1993) 288-298, 1993.
Inspire Record 355172 DOI 10.17182/hepdata.28868

We have studied c (charm) and b (bottom) quark production at the TRISTAN energy region by tagging prompt electrons from the semileptonic decays. Electrons were identified over a wide momentum range between 1 and 29 GeV/ c by a transition-radiation-detector in addition to a lead-glass calorimeter. The production cross sections of c and b quarks and the mean values of the fragmentation functions for c and b quarks were obtained as σ c = 55.9±8.8(stat.)±7.9(syst.) pb, σ b = 13.1±2.9(stat.)±1.0(syst.) pb, 〈 x c 〉 = 0.44±0.08(stat.)±0.04(syst.) and 〈 x b 〉 = 0.72±0.12(stat.)±0.08(syst.), respectively. The forward-backward asymmetries of the c and b quarks were also measured to be −0.57±0.16(stat.)±0.06(syst.) and −0.64±0.26(stat.)± 0.07(syst.), respectively. Both the cross sections and the forward-backward asymmetries of the c and b quarks are consistent with the standard model.

2 data tables

No description provided.

No description provided.


Measurement of the inclusive B* cross-section above the Upsilon (4S)

The CLEO-II collaboration Akerib, D.S. ; Barish, B. ; Cowen, D.F. ; et al.
Phys.Rev.Lett. 67 (1991) 1692-1695, 1991.
Inspire Record 29927 DOI 10.17182/hepdata.19887

Using the CLEO II detector at the Cornell Electron Storage Ring, we have determined the inclusive B* cross section above the Υ(4S) resonance in the energy range from 10.61 to 10.70 GeV. We also report a new measurement of the energy of the B*→Bγ transition photon of 46.2±0.3±0.8 MeV.

2 data tables

Hadronic cross section above the continuum. The final state is an unknown mixture of B BBAR + B* BBAR + B B*BAR (+ B* B*BAR only at the highest energy).

Inclusive B* cross section.


Measurement of the forward - backward asymmetry in Z ---> b anti-b and Z ---> c anti-c

The ALEPH collaboration Decamp, D. ; Deschizeaux, B. ; Goy, C. ; et al.
Phys.Lett.B 263 (1991) 325-336, 1991.
Inspire Record 316148 DOI 10.17182/hepdata.29386

From a sample of 150 000 hadronic Z decays collected with the ALEPH detector at LEP, events containing prompt leptons are used to measure the forward-backward asymmetries for the channels Z → b b and Z → c c , giving the results A FB b =0.126±0.028±0.012 and A FB c =0.064±0.039±0.030. These asymmetries correspond to the value of effective electroweak mixing angle at the Z mass sin 2 θ W ( m Z 2 ) = 0.2262±0.0053.

4 data tables

b asymmetry from high pt leptons.

b asymmetry from full pt range.

b asymmetry from full pt range.

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A Search for substructure of leptons and quarks with the CELLO detector

The CELLO collaboration Behrend, H.J. ; Criegee, L. ; Field, J.H. ; et al.
Z.Phys.C 51 (1991) 149-156, 1991.
Inspire Record 301727 DOI 10.17182/hepdata.14981

Differential cross section data of the CELLO experiment on pair production of muons, taus, and heavy quarks ine+e−-annihilation are presented and analysed, together with our data on Bhabha scattering, in terms of compositeness effects characterized by the mass scale Λ. We discuss difficulties in the combination of limits Λ from different experiments. The appropriate parameter to combine different results turns out to be ɛ=±1/Λ2, which is in contrast to Λ Gaussian distributed.

10 data tables

Errors are combined statistics and systematics.

Errors are combined statistics and systematics.

Errors are combined statistics and systematics.

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A Measurement of the Z0 ---> b anti-b forward - backward asymmetry

The L3 collaboration Adeva, B. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 252 (1990) 713-721, 1990.
Inspire Record 301901 DOI 10.17182/hepdata.29506

We have measured the forward-backward asymmetry in Z 0 → b b decays using hadronic events containing muons and electrons. The data sample corresponds to 118 200 hadronic events at √ s ≈ M z . From a fit to the single and dilepton p and P ⊥ spectra, we determine A b b =0.130 −0.042 +0.044 including the correction for B 0 − B 0 mixing.

3 data tables

Observed asymmetry from fit to single and dilepton P and PT spectra assuming no mixing.

Asymmetry corrected for the effects of mixing using the L3 observed mixing parameter chi(B) = 0.178 +0.049,-0.040.

SIN2TW determined from the asymmetry measurement.


Measurement of $\Z^0 \to b \bar{b}$ Decay Properties

The L3 collaboration Adeva, B. ; Adriani, O. ; Aguilar-Benitez, M. ; et al.
Phys.Lett.B 241 (1990) 416-424, 1990.
Inspire Record 295040 DOI 10.17182/hepdata.29716

We have measured the properties of Z 0 → b b decays using a sample of 944 inclusive muon events, corresponding to 18 000 hadron events obtained with the L3 detector at LEP. We measured the partial decay width of the Z 0 into b b , Γ b b =353±48 MeV , and we determined the vector coupling of the Z 0 to the b quark; g rmv 2 (b)=0.095±0.047. We measured the forward-backward charge asymmetry in e + e − → b b events at √ s ≈ M v , and obtained A b b =13.3±9.9% .

1 data table

BOTTOM quark charge asymmetry measurement.


A Measurement of the Weak Axial Couplings of the $b$ and $c$ Quark

The JADE collaboration Elsen, E. ; Allison, J. ; Ambrus, K. ; et al.
Z.Phys.C 46 (1990) 349-360, 1990.
Inspire Record 282535 DOI 10.17182/hepdata.15241

The forward-backward charge asymmetries of theb andc quarks are measured with the JADE detector at PETRA at\(\sqrt s= 35\) GeV and 44 GeV using both electrons and muons to tag the heavy quarks. At\(\sqrt s= 35\) GeV, a simultaneous fit for the two asymmetries yields the resultAb=−9.3±5.2% (state.) ndAc=−9.6±4.0% (stat.). The systematic errors are comparable with the statistical uncertainties. Combining the measurements at both energies and alternately constraining the weak coupling of thec andb quark to their Standard Model values (ac=1,ab=−1) increases the precision of the measurement of coupling constant of the other quark. Using this procedureab=−0.72±0.34 andac=0.79±0.40, where the numbers are corrected for\(B\bar B - mixing\) and the errors include both statistical and systematic contributions. The mixing parameter for continuum\(b\bar b - production\) is determined to be χ-0.24±0.12 if both heavy quark coupling constants are constrained to their values in the Standard Model.

4 data tables

Results of simultaneous fit to both asymmetries. This table is for the CHARMED quark.

Results of simultaneous fit to both asymmetries. This table is for the BOTTOM quark.

Results for BOTTOM quark asymmetry with c asymmetry constrained to the standard model value.

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