Data on jet masses, resulting from the decomposition ofe+e− hadronic final states into two hemispheres, are presented at centre of mass energies between 12 and 43.5 GeV. Comparisons are made with bareO(αs2) QCD predictions as well as with QCD based fragmentation models. Values for αs and\(\Lambda _{\overline {MS} } \) are determined, both with and without hadronization effects included. Upper and lower limits for\(\Lambda _{\overline {MS} } \) independent of fragmentation models have been determined to be 0.480±0.025 GeV and 0.047±0.007 GeV respectively.
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The value of the strong coupling constant,$$\alpha _s (M_{Z^0 } )$$, is determined from a study of 15 d
Differential jet mass distribution for the heavier jet using method T. The data are corrected for the finite acceptance and resolution of the detector and for initial state photon radiation.
Differential jet mass distribution for the jet mass difference using methodT. The data are corrected for the finite acceptance and resolution of the detec tor and for initial state photon radiation.
Differential jet mass distribution for the heavier jet using method M. The data are corrected for the finite acceptance and resolution of the detector and for initial state photon radiation.
The strong coupling constant, αs, has been determined in hadronic decays of theZ0 resonance, using measurements of seven observables relating to global event shapes, energy correlatio
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
Data corrected for finite acceptance and resolution of the detector and for intial state photon radiation. No corrections for hadronic effects are applied.. Errors include statistical and systematic uncertainties, added in quadrature.
The dijet invariant mass distribution has been measured in the region between 140 and 1000 GeV/c2, in 1.8 TeV p p¯ collisions. Data collected with the Collider Detector at Fermilab show agreement with QCD calculations. A limit on quark compositeness of Λc>1.3 TeV is obtained. Axigluons with masses between 240 and 640 GeV/c2 are excluded at 95% C.L. if we assume ten open decay channels. Model-independent limits on the production of heavy particles decaying into two jets are also presented.
No description provided.
Differential dijet cross sections have been measured with the ZEUS detector for photoproduction events in which the hadronic final state containing the jets is separated with respect to the outgoing proton direction by a large rapidity gap. The cross section has been measured as a function of the fraction of the photon (x_gamma^OBS) and pomeron (beta^OBS) momentum participating in the production of the dijet system. The observed x_gamma^OBS dependence shows evidence for the presence of a resolved- as well as a direct-photon component. The measured cross section d(sigma)/d(beta^OBS) increases as beta^OBS increases indicating that there is a sizeable contribution to dijet production from those events in which a large fraction of the pomeron momentum participates in the hard scattering. These cross sections and the ZEUS measurements of the diffractive structure function can be described by calculations based on parton densities in the pomeron which evolve according to the QCD evolution equations and include a substantial hard momentum component of gluons in the pomeron.
Differential cross section as a function of rapidity of the two highest Et jets in event.
Differential cross section as a function of transverse energy Et of the tw o highest Et jets in event.
Differential cross section as a function of invariant mass of the GAMMA P system.
The cross section for the photoproduction of events containing three jets with a three-jet invariant mass of M_3J > 50 GeV has been measured with the ZEUS detector at HERA. The three-jet angular distributions are inconsistent with a uniform population of the available phase space but are well described by parton shower models and O(alpha alpha_s^2) pQCD calculations. Comparisons with the parton shower model indicate a strong contribution from initial state radiation as well as a sensitivity to the effects of colour coherence.
Cross section in the specified kinematic range.
The measured 3-jet cross-section w.r.t. the 3-jet invariant mass.
The measured distribution in THETA(P=3).
We present a measurement of the cross section for production of two or more jets as a function of dijet mass, based on an integrated luminosity of 86 pb^-1 collected with the Collider Detector at Fermilab. Our dijet mass spectrum is described within errors by next-to-leading order QCD predictions using CTEQ4HJ parton distributions, and is in good agreement with a similar measurement from the D0 experiment.
The differential cross section for two or more jets as a function of the dijet mass.
Results are presented from analyses of jet data produced in pbarp collisions at sqrt{s} = 630 and 1800 GeV collected with the DO detector during the 1994-95 Fermilab Tevatron Collider run. We discuss details of detector calibration, and jet selection criteria in measurements of various jet production cross sections at sqrt{s} = 630 and 1800 GeV. The inclusive jet cross sections, the dijet mass spectrum, the dijet angular distributions, and the ratio of inclusive jet cross sections at sqrt{s} = 630 and 1800 GeV are compared to next-to-leading-order QCD predictions. The order alpha_s^3 calculations are in good agreement with the data. We also use the data at sqrt{s} = 1800 GeV to rule out models of quark compositeness with a contact interaction scale less than 2.2 TeV at the 95% confidence level.
The inclusive single jet cross section as a function of ET for ABS(ETARAP) < 0.5 at c.m. energy 1800 GeV.
The inclusive single jet cross section as a function of ET for ABS(ETARAP) 0.1 to 0.7 at c.m. energy 1800 GeV.
The inclusive single jet cross section as a function of ET and XT for ABS(ETARAP) < 0.5 at c.m. energy 630 GeV.
Dijet production has been studied in neutral current deep inelastic e+p scattering for 470 < Q**2 < 20000 GeV**2 with the ZEUS detector at HERA using an integrated luminosity of 38.4 pb**{-1}. Dijet differential cross sections are presented in a kinematic region where both theoretical and experimental uncertainties are small. Next-to-leading-order (NLO) QCD calculations describe the measured differential cross sections well. A QCD analysis of the measured dijet fraction as a function of Q**2 allows both a precise determination of alpha_s(M_Z) and a test of the energy-scale dependence of the strong coupling constant. A detailed analysis provides an improved estimate of the uncertainties of the NLO QCD cross sections arising from the parton distribution functions of the proton. The value of alpha_s(M_Z), as determined from the QCD fit, is alpha_s(M_Z) = 0.1166 +- 0.0019 (stat.) {+ 0.0024}_{-0.0033} (exp.)} {+ 0.0057}_{- 0.0044} (th.).
The differential dijet cross section dsig/dZP1.
The differential dijet cross section dsig/dlog10(x).
The differential dijet cross section dsig/dlog10(xi).
The production rates and substructure of jets have been studied in charged current deep inelastic e+p scattering for Q**2>200 GeV**2 with the ZEUS detector at HERA using an integrated luminosity of 110.5 pb**-1. Inclusive jet cross sections are presented for jets with transverse energies E_T(jet) > 14 GeV and pseudorapidities in the range -1 < eta(jet) < 2. Dijet cross sections are presented for events with a jet having E_T(jet) > 14 GeV and a second jet having E_T(jet) > 5 GeV. Measurements of the mean subjet multiplicity, <n_sbj>, of the inclusive jet sample are presented. Predictions based on parton-shower Monte Carlo models and next-to-leading-order QCD calculations a re compared to the measurements. The value of alphas(M_Z), determined from <n_sbj> at y_cut=0.01 for jets with 25<E_T(jet)<119 GeV, is alphas(M_Z) = 0.1202 +-0.0052 (stat.) +0.0060-0.0019 (syst.) +0.0065-0.0053 (th.). The mean subjet multiplicity as a function of Q**2 is found to be consistent with that measured in NC DIS.
Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the 1995-1997 sample.
Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the 1999-2000 sample.
Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the combined sample.
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