Inclusive production of pi0, eta, eta'(958), K0(S) and Lambda in two- and three-jet events from hadronic Z decays.

The ALEPH collaboration Barate, R. ; Decamp, D. ; Ghez, Philippe ; et al.
Eur.Phys.J.C 16 (2000) 613, 2000.
Inspire Record 507531 DOI 10.17182/hepdata.49106

The production rates and the inclusive cross sections of the isovector meson${\rm \pi^0}$, the isoscalar mesons$\eta$and

25 data tables

Inclusive cross section for PI0 production in hadronic events.

Inclusive cross section for ETA production in hadronic events.

Inclusive cross section for ETAPRIME production in hadronic events.

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Measurement of the photon structure function F2(gamma) at low x.

The OPAL collaboration Ackerstaff, K. ; Alexander, G. ; Allison, John ; et al.
Phys.Lett.B 412 (1997) 225-234, 1997.
Inspire Record 447187 DOI 10.17182/hepdata.49560

Deep inelastic electron-photon scattering is studied using e+e- data collected by the OPAL detector at centre-of-mass energies sqrt{s_ee} ~ M_{Z^0}. The photon structure function F_2^gamma(x,Q^2) is explored in a Q^2 range of 1.1 to 6.6 GeV/c^2 at lower x values than ever before. To probe this kinematic region events are selected with a beam electron scattered into one of the OPAL luminosity calorimeters at scattering angles between 27 and 55 mrad. A measurement is presented of the photon structure function F_2^gamma(x,Q^2) at <Q^2> = 1.86 GeV^2 and 3.76 GeV^2 in five logarithmic x bins from 0.0025 to 0.2.

2 data tables

Measurement of the hadron photon structure function. Systematic errors do not contain any effects caused by the four momentum of the quasi-real photon being non zero.

Measurement of the hadron photon structure function. Systematic errors do not contain any effects caused by the four momentum of the quasi-real photon being non zero.


The scale dependence of the hadron multiplicity in quark and gluon jets and a precise determination of C(A)/C(F).

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 449 (1999) 383-400, 1999.
Inspire Record 495414 DOI 10.17182/hepdata.49173

Data collected at the Z resonance using the DELPHI detector at LEP are used to determine the charged hadron multiplicity in gluon and quark jets as a function of a transverse momentum-like scale. The colour factor ratio, \cacf, is directly observed in the increase of multiplicities with that scale. The smaller than expected multiplicity ratio in gluon to quark jets is understood by differences in the hadronization of the leading quark or gluon. From the dependence of the charged hadron multiplicity on the opening angle in symmetric three-jet events the colour factor ratio is measured to be: C_A/C_F = 2.246 \pm 0.062 (stat.) \pm 0.080 (syst.) \pm 0.095 (theo.)

3 data tables

Charged multiplicity in events with a hard photon, as a function of the apparent centre-of-mass energy (SQRT(S)) of the hadronic system. The errors shown are statistical only.

Charged multiplicity in symmetric three jet events as function of the opening angle between the low energetic jets, THETA1. Jets are defined from charged and neutral particles using the DURHAM algorithm. The errors shown are statistical only.

Twice the difference of the multiplicity in three jet events and in qqbar events of comparable scale 2(N_3jet-N_qqbar). The three-jet event multiplicity isequal to the data of Fig. 3c), the qqbar-multiplicity is taken from a fit of th e e+e- data corrected for the varying b-quark contribution. This multiplicity can be identified with the multiplicity of a hypothetical gluon-gluon event. Thereis a normalization uncertainty (i.e. a scale independent constant) of the gluon -gluon event multiplicity which should not influence the slope of the gg-multiplicity with scale (see paper). The errors shown are statistical only.


pi+-, K+-, p and anti-p production in Z0 --> q anti-q, Z0 --> b anti-b, Z0 --> u anti-u, d anti-d, s anti-s.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 5 (1998) 585-620, 1998.
Inspire Record 473409 DOI 10.17182/hepdata.49385

The DELPHI experiment at LEP uses Ring Imaging Cherenkov detectors for particle identification. The good understanding of the RICH detectors allows the identification of charged pions, kaons and proto

39 data tables

Mean particle multiplicities for Z0-->Q-QBAR events. The second systematic (DSYS) error is due to the extrapolation of the differential distributions to the full kinematic range.

Mean particle multiplicities for Z0-->B-BBAR events. The second systematic (DSYS) error is due to the extrapolation of the differential distributions to the full kinematic range.

Mean particle multiplicities for Z0-->(U-UBAR,D-DBAR,S-SBAR) events. The second systematic (DSYS) error is due to the extrapolation of the differential distributions to the full kinematic range.

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Investigation of the splitting of quark and gluon jets.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J.C 4 (1998) 1-17, 1998.
Inspire Record 467927 DOI 10.17182/hepdata.49547

The splitting processes in identified quark and gluon jets are investigated using longitudinal and transverse observables. The jets are selected from symmetric three-jet events measured in Z decays with the Delphi detector in 1991-1994. Gluon jets are identified using heavy quark anti-tagging. Scaling violations in identified gluon jets are observed for the first time. The scale energy dependence of the gluon fragmentation function is found to be about two times larger than for the corresponding quark jets, consistent with the QCD expectation CA/CF. The primary splitting of gluons and quarks into subjets agrees with fragmentation models and, for specific regions of the jet resolution y, with NLLA calculations. The maximum of the ratio of the primary subjet splittings in quark and gluon jets is 2.77±0.11±0.10. Due to non-perturbative effects, the data are below the expectation at small y. The transition from the perturbative to the non-perturbative domain appears at smaller y for quark jets than for gluon jets. Combined with the observed behaviour of the higher rank splittings, this explains the relatively small multiplicity ratio between gluon and quark jets.

14 data tables

Scaled energy distribution of charged hadrons produced in Quark jets in 'Y'topology 3-JET events.

Scaled energy distribution of charged hadrons produced in Gluon jets in 'Y'topology 3-JET events.

Scaled energy distribution of charged hadrons produced in Quark jets in 'Mercedes' topology 3-JET events.

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The forward-backward asymmetry for charm quarks at the Z.

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.
Phys.Lett.B 434 (1998) 415-425, 1998.
Inspire Record 472954 DOI 10.17182/hepdata.49353

The data set collected with the ALEPH detector from 1991 to 1995 at LEP has been analysed to measure the charm forward-backward asymmetry at the Z. Out of a total of 4.1 million hadronic Z decays, about 36000 high momentum D*+, D+ and D0 decays were reconstructed, of which 80% originate from Z -> ccbar events...

2 data tables

No description provided.

No description provided.


Determination of A(b)(FB) using jet charge measurements in Z decays.

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.
Phys.Lett.B 426 (1998) 217-230, 1998.
Inspire Record 468671 DOI 10.17182/hepdata.49559

An improved measurement of the forward-backward asymmetry in Z →b b ̄ decays is presented, based on a sample of 4.1 million hadronic Z decays collected by ALEPH between 1991 and 1995. Data are analysed as a function of polar angle of the event axis and b purity. The event tagging efficiency and mean b -jet hemisphere charge are measured directly from data. From the measured forward-backward jet charge asymmetry, the b quark asymmetry at s =m Z is determined to be: A b FB =0.1017±0.0038(stat.)±0.0032(syst.). In the context of the Standard Model this corresponds to a value of the effective weak mixing angle of sin 2 θ W eff =0.23109±0.00096.

3 data tables

Only statistical errors are given for sqrt(s) = 89.43 and 92.97 GeV.

The combination of the data on and off peak of Z-boson.

The combination of the data on and off peak of Z-boson.


Measurement of the multiplicity of gluons splitting to bottom quark pairs in hadronic Z0 decays.

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett.B 405 (1997) 202-214, 1997.
Inspire Record 442880 DOI 10.17182/hepdata.47486

An inclusive measurement of the average multiplicity of b b pairs from gluons, g b b , in hadronic Z 0 events collected by the DELPHI experiment at LEP, is presented. A counting technique, based on jet b -tagging in 4-jet events, has been used. Looking for secondary bottom production in events with production of any primary flavour, by requiring two b -tagged jets in well defined topological configurations, gave g b b = (0.21 ± 0.11 ( stat ) ± 0.09 ( syst ))% . This result was checked with a different method designed to select events with four b quarks in the final state. Agreement within the errors was found.

1 data table

No description provided.


Measurement of f(c --> D*+ X), f(b --> D*+ X) and Gamma(c anti-c)/Gamma(had) using D*+- mesons.

The OPAL collaboration Ackerstaff, K. ; Alexander, G. ; Allison, John ; et al.
Eur.Phys.J.C 1 (1998) 439-459, 1998.
Inspire Record 447145 DOI 10.17182/hepdata.47409

The production rates of D^*+/- mesons in charm and bottom events at centre-of-mass energies of about 91 GeV and the partial width of primary cc(bar) pairs in hadronic Z^0 decays have been measured at LEP using almost 4.4 million hadronic Z^0 decays collected with the OPAL detector between 1990 and 1995. Using a combination of several charm quark tagging methods based on fully and partially reconstructed D^*+/- mesons, and a bottom tag based on identified muons and electrons, the hadronisation fractions of charm and bottom quarks into D^*+/- mesons have been found to be: f(b -> D^*+ X) = 0.173 +/- 0.016 +/- 0.012 and f(c -> D^*+ X) = 0.222 +/- 0.014 +/- 0.014 The fraction of cc(bar) events in hadronic Z^0 decays, Gamma_cc(bar)/Gamma_had = Gamma(Z^0 -> cc(bar))/Gamma(Z^0 -> hadrons), is determined to be Gamma_cc(bar)/Gamma_had = 0.180 +/- 0.011 +/- 0.012 +/- 0.006 In all cases the first error is statistical, and the second one systematic. The last error quoted for Gamma_cc(bar)/Gamma_had is due to external branching ratios.

3 data tables

No description provided.

No description provided.

The second syst. errors results due to extranal branching ratios. Charge conjugated states are implied. FD is considered as a quark fragmentation fraction. Sqrt(s(E+ E-)) = 91.2 GeV.


Precise Measurement of the Left-Right Cross Section Asymmetry in $Z$ Boson Production by $\ee$ Collisions

The SLD collaboration Abe, K. ; Abt, I. ; Ash, W.W. ; et al.
Phys.Rev.Lett. 73 (1994) 25-29, 1994.
Inspire Record 373007 DOI 10.17182/hepdata.19681

We present a precise measurement of the left-right cross section asymmetry ($A_{LR}$) for $Z$ boson production by $\ee$ collisions. The measurement was performed at a center-of-mass energy of 91.26 GeV with the SLD detector at the SLAC Linear Collider (SLC). The luminosity-weighted average polarization of the SLC electron beam was (63.0$\pm$1.1)%. Using a sample of 49,392 $\z0$ decays, we measure $A_{LR}$ to be 0.1628$\pm$0.0071(stat.)$\pm$0.0028(syst.) which determines the effective weak mixing angle to be $\swein=0.2292\pm0.0009({\rm stat.})\pm0.0004({\rm syst.})$.}

2 data tables

The observed, corrected, asymmetry. L and R refer to the left and right handed beam polarizations.

The left-right asymmetry and effective weak mixing angle corrected to the pole energy value, taking into account photon exchange and electro weak interferences. L and R refer to left and right beam polarizations.