Substructure dependence of jet cross sections at HERA and determination of alpha(s).

The ZEUS collaboration Chekanov, S. ; Derrick, M. ; Loizides, J.H. ; et al.
Nucl.Phys.B 700 (2004) 3-50, 2004.
Inspire Record 650732 DOI 10.17182/hepdata.46136

Jet substructure and differential cross sections for jets produced in the photoproduction and deep inelastic ep scattering regimes have been measured with the ZEUS detector at HERA using an integrated luminosity of 82.2 pb-1. The substructure of jets has been studied in terms of the jet shape and subjet multiplicity for jets with transverse energies Et(jet) > 17 GeV. The data are well described by the QCD calculations. The jet shape and subjet multiplicity are used to tag gluon- and quark-initiated jets. Jet cross sections as functions of Et(jet), jet pseudorapidity, the jet-jet scattering angle, dijet invariant mass and the fraction of the photon energy carried by the dijet system are presented for gluon- and quark-tagged jets. The data exhibit the behaviour expected from the underlying parton dynamics. A value of alphas(Mz) of alphas(Mz) = 0.1176 +-0.0009(stat.) -0.0026 +0.0009 (exp.) -0.0072 +0.0091 (th.) was extracted from the measurements of jet shapes in deep inelastic scattering.

31 data tables

Measured mean integrated jet shape corrected to the hadron level in photoproduction with ET(C=JET) > 17 GeV.

Measured mean integrated jet shape corrected to the hadron level in photoproduction with ET(C=JET) > 17 GeV.

Measured mean integrated jet shape corrected to the hadron level in photoproduction with -1 < ETARAP(C=JET) < 2.5.

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Measurement of internal jet structure in dijet production in deep inelastic scattering at HERA

The H1 collaboration Adloff, C. ; Andreev, V. ; Andrieu, B. ; et al.
Nucl.Phys.B 545 (1999) 3-20, 1999.
Inspire Record 482053 DOI 10.17182/hepdata.32577

Internal jet structure in dijet production in deep-inelastic scattering is measured with the H1 detector at HERA. Jets with transverse energies ET,Breit > 5 GeV are selected in the Breit frame employing k_perp and cone jet algorithms. In the kinematic region of squared momentum transfers 10 < Q2 <~ 120 GeV2 and x-Bjorken values 2.10^-4 <~ xBj <~ 8.10^-3, jet shapes and subjet multiplicities are measured as a function of a resolution parameter. Distributions of both observables are corrected for detector effects and presented as functions of the transverse jet energy and jet pseudo-rapidity. Dependences of the jet shape and the average number of subjets on the transverse energy and the pseudo-rapidity of the jet are observed. With increasing transverse jet energies and decreasing pseudo-rapidities, i.e.towards the photon hemisphere, the jets are more collimated. QCD models give a fair description of the data.

24 data tables

The dependence of the jet shapes on the transverse jet energy ET in the pseudorapidity range < 1.5 and the ET range 5 TO 8 GeV using the inclusive KT jet finding algorithm.

The dependence of the jet shapes on the transverse jet energy ET in the pseudorapidity range 1.5 TO 2.2 and the ET range 5 TO 8 GeV using the inclusive KT jet finding algorithm.

The dependence of the jet shapes on the transverse jet energy ET in the pseudorapidity range > 2.2 and the ET range 5 TO 8 GeV using the inclusive KT jet finding algorithm.

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Measurement of jet shapes in high Q**2 deep inelastic scattering at HERA

The ZEUS collaboration Breitweg, J. ; Derrick, M. ; Krakauer, D. ; et al.
Eur.Phys.J.C 8 (1999) 367-380, 1999.
Inspire Record 468803 DOI 10.17182/hepdata.44312

The shapes of jets with transverse energies, E_T(jet), up to 45 GeV produced in neutral- and charged-current deep inelastic e+p scattering (DIS) at Q**2 > 100 GeV**2 have been measured with the ZEUS detector at HERA. Jets are identified using a cone algorithm in the eta-phi plane with a cone radius of one unit. The jets become narrower as E_T(jet) increases. The jet shapes in neutral- and charged-current DIS are found to be very similar. The jets in neutral-current DIS are narrower than those in resolved processes in photoproduction and closer to those in direct-photon processes for the same ranges in E_T(jet) and jet pseudorapidity. The jet shapes in DIS are observed to be similar to those in e+e- interactions and narrower than those in pbarp collisions for comparable E_T(jet). Since the jets in e+e- interactions and e+p DIS are predominantly quark initiated in both cases, the similarity in the jet shapes indicates that the pattern of QCD radiation within a quark jet is to a large extent independent of the hard scattering process in these reactions.

24 data tables

Measured differential jet shapes, corrected to the hadron level, in neutral-current DIS for jets with ET greater than 14 GeV in different etarap regions.

Measured differential jet shapes, corrected to the hadron level, in neutral-current DIS for jets with ET greater than 14 GeV in different etarap regions.

Measured differential jet shapes, corrected to the hadron level, in neutral-current DIS for jets with ET greater than 14 GeV in different etarap regions.

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