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Measurement of the gluon fragmentation function and a comparison of the scaling violation in gluon and quark jets

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J. C13 (2000) 573-589, 2000.
Inspire Record 511099 DOI 10.17182/hepdata.49028
7 data tables

Charged hadron XE(=Z) distributions. Durham algorithm. XISTAR is peak position in XI=LOG(-XE) distribution.

Charged hadron XE(=Z) distributions. Durham algorithm. XISTAR is peak position in XI=LOG(-XE) distribution.

Charged hadron XE(=Z) distributions. Durham algorithm. XISTAR is peak position in XI=LOG(-XE) distribution.

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Measurement of the probability of gluon splitting into charmed quarks in hadronic $Z$ decays

The L3 collaboration Acciarri, M. ; Achard, P. ; Adriani, O. ; et al.
Phys.Lett. B476 (2000) 243-255, 2000.
Inspire Record 510061 DOI 10.17182/hepdata.49044

We have measured the probability, n(g->cc~), of a gluon splitting into a charm-quark pair using 1.7 million hadronic Z decays collected by the L3 detector. Two independent methods have been applied to events with a three-jet topology. One method relies on tagging charmed hadrons by identifying a lepton in the lowest energy jet. The other method uses a neural network based on global event shape parameters. Combining both methods, we measure n(g->cc~)= [2.45 +/- 0.29 +/- 0.53]%.

1 data table

No description provided.


Identified charged particles in quark and gluon jets

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Eur.Phys.J. C17 (2000) 207-222, 2000.
Inspire Record 524696 DOI 10.17182/hepdata.50064

A sample of 2.2 million hadronic Z decays, selected from the data recorded by the Delphi detector at LEP during 1994-1995 was used for an improved measurement of inclusive distributions of pi+, K+ and p and their antiparticles in gluon and quark jets. The production spectra of the individual identified particles were found to be softer in gluon jets compared to quark jets, with a higher multiplicity in gluon jets as observed for inclusive charged particles. A significant proton enhancement in gluon jets is observed indicating that baryon production proceeds directly from colour objects. The maxima, xi^*, of the xi-distributions for kaons in gluon and quark jets are observed to be different.

11 data tables

Jet flavor tagging is used. (C=DUSCB), (C=DUSC), (C=UDS) mean quark-jet flavors. CONST(C=GLUON/JET) is the ratio gluon/jet for all charged particles. 'Y' events, mirror symmetric events, the angle between the most energetic jet and other two jets is 150 +- 15 deg.

Jet flavor tagging is used. (C=DUSCB), (C=DUSC), (C=UDS) mean quark-jet flavors. CONST(C=GLUON/JET) is the ratio gluon/jet for all charged particles. 'Y' events, mirror symmetric events, the angle between the most energetic jet and other two jets is 150 +- 15 deg.

Jet flavor tagging is used. (C=DUSCB), (C=DUSC), (C=UDS) mean quark-jet flavors. CONST(C=GLUON/JET) is the ratio gluon/jet for all charged particles. 'Y' events, mirror symmetric events, the angle between the most energetic jet and other two jets is 150 +- 15 deg.

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Production rates of b anti-b quark pairs from gluons and b anti-b b anti-b events in hadronic Z0 decays

The OPAL collaboration Abbiendi, G. ; Ackerstaff, K. ; Ainsley, C. ; et al.
Eur.Phys.J. C18 (2001) 447-460, 2001.
Inspire Record 535059 DOI 10.17182/hepdata.49875

The rates are measured per hadronic Z decay for gluon splitting to bb(bar) quark pairs, g_bb, and of events containing two bb(bar) quark pairs, g_4b, using a sample of four-jet events selected from data collected with the OPAL detector. Events with an enhanced signal of gluon splitting to bb(bar) quarks are selected if two of the jets are close in phase-space and contain detached secondary vertices. For the event sample containing two bb(bar) quark pairs, three of the four jets are required to have a significantly detached secondary vertex. Information from the event topology is combined in a likelihood fit to extract the values of g_bb and g_4b, namely g_bb = (3.07 +- 0.53(stat) +- 0.97(syst))x10^-3 g_4b = (0.36 +- 0.17(stat) +- 0.27(syst))x10^-3

1 data table

No description provided.


Measurements of the structure of quark and gluon jets in hadronic Z decays

The ALEPH collaboration Barate, R. ; Buskulic, D. ; Decamp, D. ; et al.
Eur.Phys.J. C17 (2000) 1-18, 2000.
Inspire Record 467225 DOI 10.17182/hepdata.49549
6 data tables

The measured jet broadening distributions (B) in quark and gluon jets seperately.

Measured distributions of -LN(Y2), where Y2 is the differential one-subjet rate, that is the value of the subjet scale parameter where 2 jets appear from the single jet.

The mean subjet multiplicity (-1) for gluon jets and quark jets for different values of the subject resolution parameter Y0.

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Improved measurement of the probability for gluon splitting into b anti-b in Z0 decays

The SLD collaboration Abe, Koya ; Abe, Kenji ; Abe, T. ; et al.
Phys.Lett. B507 (2001) 61-69, 2001.
Inspire Record 552756 DOI 10.17182/hepdata.41701
1 data table

No description provided.


Production of K0(S) and Lambda in quark and gluon jets from Z0 decay

The OPAL collaboration Ackerstaff, K. ; Alexander, G. ; Allison, John ; et al.
Eur.Phys.J. C8 (1999) 241-254, 1999.
Inspire Record 470732 DOI 10.17182/hepdata.49497

The production of K^0_S mesons and Lambda baryons in quark and gluon jets has been investigated using two complementary techniques. In the first approach, which provides high statistical accuracy, jets were selected using different jet finding algorithms and ordered according to their energy. Production rates were determined taking into account the dependences of quark and gluon compositions as a function of jet energy as predicted by Monte Carlo models. Selecting three-jet events with the k_perp (Durham) jet finder (y_cut = 0.005), the ratios of K^0_S and Lambda production rates in gluon and quark jets relative to the mean charged particle multiplicity were found to be 1.10 +/- 0.02 +/- 0.02 and 1.41 +/- 0.04 +/- 0.04, respectively, where the first uncertainty is statistical and the second is systematic. In the second approach, a new method of identifying quark jets based on the collimation of energy flow around the jet axis is introduced and was used to anti-tag gluon jets in symmetric (Y-shaped) three-jet events. Using the cone jet finding algorithm with a cone size of 30 degrees, the ratios of relative production rates in gluon and quark jets were determined to be 0.94 +/- 0.07 +/- 0.07 for K^0_S and 1.18 +/- 0.10 +/- 0.17 for Lambda. The results of both analyses are compared to the predictions of Monte Carlo models.

2 data tables

Ratios of relative yields.

Ratios of absolute rates.


Quark and gluon jet properties in symmetric three jet events

The ALEPH collaboration Buskulic, D. ; Casper, D. ; De Bonis, I. ; et al.
Phys.Lett. B384 (1996) 353-364, 1996.
Inspire Record 404562 DOI 10.17182/hepdata.48015
2 data tables

B-jets are identified with the lepton-tag analysis.

The same kinematics as in the table 1.


Energy dependence of the differences between the quark and gluon jet fragmentation

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Z.Phys. C70 (1996) 179-196, 1996.
Inspire Record 403254 DOI 10.17182/hepdata.48064
2 data tables

No description provided.

Durham and JADE algoritms were used.


Identified particles in quark and gluon jets

The DELPHI collaboration Abreu, P. ; Adam, W. ; Adye, T. ; et al.
Phys.Lett. B401 (1997) 118-130, 1997.
Inspire Record 428228 DOI 10.17182/hepdata.47615
2 data tables

Y events.

Mercedes events.


A Study of differences between quark and gluon jets using vertex tagging of quark jets

The OPAL collaboration Acton, P.D. ; Alexander, G. ; Allison, John ; et al.
Z.Phys. C58 (1993) 387-404, 1993.
Inspire Record 352789 DOI 10.17182/hepdata.48418
1 data table

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. B265 (1991) 462-474, 1991.
Inspire Record 316872 DOI 10.17182/hepdata.48454
1 data table

QUARK means QUARK or QUARKBAR.


First measurement of the t odd correlation between the Z0 spin and the three jet plane orientation in polarized Z0 decays to three jets

The SLD collaboration Abe, K. ; Abt, I. ; Ahn, C.J. ; et al.
Phys.Rev.Lett. 75 (1995) 4173-4177, 1995.
Inspire Record 400920 DOI 10.17182/hepdata.19601

We present the first measurement of the correlation between the $Z^0$ spin and the three-jet plane orientation in polarized $Z^0$ decays into three jets in the SLD experiment at SLAC utilizing a longitudinally polarized electron beam. The CP-even and T-odd triple product $\vec{S_Z}\cdot(\vec{k_1}\times \vec{k_2})$ formed from the two fastest jet momenta, $\vec{k_1}$ and $\vec{k_2}$, and the $Z^0$ polarization vector $\vec{S_Z}$, is sensitive to physics beyond the Standard Model. We measure the expectation value of this quantity to be consistent with zero and set 95\% C.L. limits of $-0.022 < \beta < 0.039$ on the correlation between the $Z^0$-spin and the three-jet plane orientation.

1 data table

Asymmetry extracted from formula: (1/SIG(Q=3JET))*D(SIG)/D(COS(OMEGA)) = 9/16*[(1-1/3*(COS(OMEGA))**2) + ASYM*Az*(1-2*Pmis(ABS(COS(OMEGA))))*COS(OMEGA)], where OMEGA is polar angle of [k1,k2] vector (jet-plane normal), Pmis is the p robability of misassignment of of jet-plane normal, Az is beam polarization. Jets were reconstructed using the 'Durham' jet algorithm with a jet-resol ution parameter Yc = 0.005.


Measurement of the multiplicity of charm quark pairs from gluons in hadronic Z0 decays

The OPAL collaboration Akers, R. ; Alexander, G. ; Allison, J. ; et al.
Phys.Lett. B353 (1995) 595-605, 1995.
Inspire Record 395451 DOI 10.17182/hepdata.48158
1 data table

Axis error includes +- 8.4/8.4 contribution (Total generator error for the electron channel due to the uncertainties in parameters of Peterson model of fragmentation, LAMBDA_QCD, ALPHA_S, Lund fragmentation parameters and lepton decay model).