Speaker
Claudia Glasman
(Univer. Autonoma De Madrid)
Description
Inclusive jet cross sections in charged current deep inelastic scattering (DIS)
and three-jet production in DIS and photoproduction were studied with the ZEUS detector at HERA.
For the study of inclusive jet-production in charged current DIS, differential
cross sections are presented as functions of Q2, Bjorken x and the jet transverse energy
and pseudorapidity. The dijet invariant mass cross section is also presented.
Observation of three- and four-jet events in charged-current e±p processes is
reported for the first time. The predictions of next-to-leading-order
(NLO) QCD calculations are compared to the measurements. The data have the potential to
constrain the u and d valence quark distributions in the proton if
included as input to global fits.
For the study of three-jet production measurements of differential cross sections are
presented as functions of angular correlations between the three jets in
the final state and the proton-beam direction. These correlations provide
a stringent test of perturbative QCD and show sensitivity to the
contributions from different colour configurations. Fixed-order
perturbative QCD calculations assuming the values of the colour factors
C_F, C_A and T_F as derived from a variety of gauge groups were compared
to the measurements to study the underlying gauge group symmetry. The
measured angular correlations in the deep inelastic ep scattering and
photoproduction regimes are consistent with the admixture of colour
configurations as predicted by SU(3) and disfavour other symmetry groups,
such as SU(N) in the limit of large N.
Subjet distributions were also measured in neutral current deep inelastic ep
scattering with the ZEUS detector at HERA using an integrated luminosity
up to 334 pb-1. Jets were identified using the kT cluster algorithm in the
laboratory frame. Subjets were defined as jet-like substructures identified
by a reapplication of the cluster algorithm at a smaller value of the
resolution parameter ycut. Measurements of subjet distributions for jets
with exactly two or three subjets are presented as functions of
observables sensitive to the pattern of parton radiation and to the colour
coherence between the initial and final states. In the case of three subjets
measurements are also presented as functions of angular correlations between
the three subjets which provide a stringent test of perturbative QCD and show sensitivity
to the contributions from different colour configurations. Perturbative
QCD predictions give an adequate description of the data.
Primary authors
Claudia Glasman
(Univer. Autonoma De Madrid)
Monica Turcato ZEUS Collaboration
(Hamburg University)
