High- ETE_TET inclusive jet cross sections in photoproduction at HERA (original) (raw)

Inclusive jet differential cross sections in photoproduction at HERA

1994

Inclusive jet differential cross sections for the reaction ep ~ jet + X at Q2 below 4 GeV 2 have been measured with the ZEUS detector at HERA using an integrated luminosity of 0.55 pb -t. These cross sections are given in the kinematic region 0.2 < y < 0.85, for jet pseudorapidities in the ep-laboratory range -1 < ~t < 2 and refer to jets at the hadron level with a cone radius of one unit in the 7/-~b plane. These results correspond to quasi-real photoproduction at centre-of-mass energies in the range 130-270 GeV and, approximately, for jet pseudorapidities in the interval -3 < r/~t(yp CMS) < 0. These measurements cover a new kinematic regime of the partonic structure of the photon, at typical scales up to ,-~300 GeV 2 and photon fractional momenta down to x~, ,-, 10 -2. Leading logarithm parton shower Monte Carlo calculations, which include both resolved and direct processes and use the predictions of currently available parametrisations of the photon patton distributions, describe in general the shape and magnitude of the measured ~et and E~ t distributions.

Measurement of inclusive jet cross sections in photoproduction at HERA

The European Physical Journal C - Particles and Fields, 2003

A measurement of inclusive jet cross-sections in deep-inelastic ep scattering at HERA is presented based on data with an integrated luminosity of 21.1 pb −1 . The measurement is performed for photon virtualities Q 2 between 5 and 100 GeV 2 , differentially in Q 2 , in the jet transverse energy E T , in E 2 T /Q 2 and in the pseudorapidity η lab . With the renormalization scale µ R = E T , perturbative QCD calculations in next-to-leading order (NLO) give a good description of the data in most of the phase space. Significant discrepancies are observed only for jets in the proton beam direction with E T below 20 GeV and Q 2 below 20 GeV 2 . This corresponds to the region in which NLO corrections are largest and further improvement of the calculations is thus of particular interest.

Measurement of two jet cross-sections in photoproduction at HERA

Work

Inclusive jet cross sections in D * ± photoproduction at HERA has been measured in photon-proton center of mass energy from 130 GeV to 280 GeV. The analysis is based on the integrated luminosity of 78.6 pb −1 taken by the ZEUS detector. D * ± was measured in the kinematic region p T (D * ) > 3 GeV/c and |η(D * )| < 1.5. Jet cross sections have been measured with the aim to have better correspondence between the observable (jet) and the outgoing parton, and also to extend the measurement towards the proton direction. Differential cross sections as a function of the transverse energy (E jet T ) and the pseudorapidity (η jet ) of jets were measured in the range E jet T > 6 GeV and −1.5 < η jet < 2.4. The η jet cross sections are reasonably described by the next-to-leading order (NLO) QCD calculation corrected for hadronization effect. The measured cross sections are larger than the NLO QCD predictions, but agrees within the theoretical uncertainty except for the highest measured E jet T where an excess of 3σ is observed. At high E jet T , by studying the ratio of the transverse momentum of the D

Inclusive jet cross sections and dijet correlations in photoproduction at HERA

Nuclear Physics B, 2005

Inclusive jet cross sections and dijet correlations in D ∗ ± photoproduction at HERA

Nuclear Physics B, 2005

Inclusive jet cross sections in photoproduction for events containing a D * meson have been measured with the ZEUS detector at HERA using an integrated luminosity of 78.6 pb −1 . The events were required to have a virtuality of the incoming photon, Q 2 , of less than 1 GeV 2 , and a photon-proton centre-ofmass energy in the range 130 < W γp < 280 GeV. The measurements are compared with next-to-leadingorder (NLO) QCD calculations. Good agreement is found with the NLO calculations over most of the measured kinematic region. Requiring a second jet in the event allowed a more detailed comparison with QCD calculations. The measured dijet cross sections are also compared to Monte Carlo (MC) models which incorporate leading-order matrix elements followed by parton showers and hadronisation. The NLO QCD predictions are in general agreement with the data although differences have been isolated to regions where contributions from higher orders are expected to be significant. The MC models give a better description than the NLO predictions of the shape of the measured cross sections.

Dijet cross sections in photoproduction at HERA

The European Physical Journal C, 1998

Dijet cross sections as functions of several jet observables are measured in photoproduction using the H1 detector at HERA. The data sample comprises e + p data with an integrated luminosity of 34.9 pb −1. Jets are selected using the inclusive k ⊥ algorithm with a minimum transverse energy of 25 GeV for the leading jet. The phase space covers longitudinal proton momentum fraction x p and photon longitudinal momentum fraction x γ in the ranges 0.05 < x p < 0.6 and 0.1 < x γ < 1. The predictions of next-to-leading order perturbative QCD, including recent photon and proton parton densities, are found to be compatible with the data in a wide kinematical range.

Measurement of di-jet cross-sections in photoproduction and photon structure

Physics Letters B, 2000

Dijet cross sections as functions of several jet observables are measured in photoproduction using the H1 detector at HERA. The data sample comprises e + p data with an integrated luminosity of 34.9 pb −1 . Jets are selected using the inclusive k ⊥ algorithm with a minimum transverse energy of 25 GeV for the leading jet. The phase space covers longitudinal proton momentum fraction x p and photon longitudinal momentum fraction x γ in the ranges 0.05 < x p < 0.6 and 0.1 < x γ < 1. The predictions of next-to-leading order perturbative QCD, including recent photon and proton parton densities, are found to be compatible with the data in a wide kinematical range.

Measurement of dijet cross sections in photoproduction at HERA

The European Physical Journal C, 2002

Inclusive D*± meson cross sections and D*±-jet correlations in photoproduction at HERA

The European Physical Journal C, 2007

Differential photoproduction cross sections are measured for events containing D * ± mesons. The data were taken with the H1 detector at the ep collider HERA and correspond to an integrated luminosity of 51.1 pb −1 . The kinematic region covers small photon virtualities Q 2 < 0.01 GeV 2 and photon-proton centre-of-mass energies of 171 < W γ p < 256 GeV. The details of the heavy quark production process are further investigated in events with one or two jets in addition to the D * ± meson. Differential cross sections for D * +jet production are determined and the correlations between the D * ± meson and the jet(s) are studied. The results are compared with perturbative QCD predictions applying collinear-or k t -factorisation.

High- ETE_TET​ inclusive jet cross sections in photoproduction at HERA (original) (raw)

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High- ETE_TET inclusive jet cross sections in photoproduction at HERA (original) (raw)