A new jet algorithm based on the k-means clustering for the reconstruction of heavy states from jets

A jet algorithm based on the k-means clustering procedure is proposed which can be used for the invariant-mass reconstruction of heavy states decaying to hadronic jets. The proposed algorithm was tested by reconstructing E+ E- to ttbar to 6 jets and E+ E- to W+W- to 4 jets processes at \sqrt{s}=500 GeV using a Monte Carlo simulation. It was shown that the algorithm has a reconstruction efficiency similar to traditional jet-finding algorithms, and leads to 25% and 40% reduction of reconstruction width for top quarks and W bosons, respectively, compared to the kT (Durham) algorithm. In addition, it is expected that the peak positions measured with the new algorithm have smaller systematical uncertainty.Comment: 11 pages, 3 eps figures (Eur. Phys. J. C, in press

Jets in Deep Inelastic Scattering and High Energy Photoproduction at HERA

Recent results on jet production in neutral current deep inelastic scattering and high energy photoproduction at the HERA electron-proton-collider are briefly reviewed. The results are compared to QCD expectations in NLO and $\alpha_s$ determinations using these data are summarized.Comment: 12 pages, 10 figures, talk given at the 9th Adriatic Meeting "Particle Physics and the Universe" in Dubrovnik/Croatia, 4.-24.9.200

Long-Range Correlations in Deep-Inelastic Scattering

Multiplicity correlations between the current and target regions of the Breit frame in deep-inelastic scattering processes are studied. It is shown that the correlations are sensitive to the first-order perturbative QCD effects and can be used to extract the behavior of the boson-gluon fusion rates as a function of the Bjorken variable. The behavior of the correlations is derived analytically and analyzed using a Monte Carlo simulation.Comment: 16 pages, 5 figures, preprint ANL-HEP-PR-98-46 (accepted by J. Phys. G

HepSim: a repository with predictions for high-energy physics experiments

A file repository for calculations of cross sections and kinematic distributions using Monte Carlo generators for high-energy collisions is discussed. The repository is used to facilitate effective preservation and archiving of data from theoretical calculations, as well as for comparisons with experimental data. The HepSim data library is publicly accessible and includes a number of Monte Carlo event samples with Standard Model predictions for current and future experiments. The HepSim project includes a software package to automate the process of downloading and viewing online Monte Carlo event samples. A data streaming over a network for end-user analysis is discussed.Comment: 12 pages, 2 figure

Angular Intermittency and Analytical QCD Predictions

We present a comparison of local multiplicity fluctuations in angular phase-space intervals with first-order QCD predictions. The data are based on 810k hadronic events at 91.2 GeV collected with the L3 detector at LEP during 1994.Comment: 4 pages, LaTeX, 1 eps figure Presented at 32th Rencontres de Moriond, ``QCD and High Energy Hadronic Interactions'' Les Arcs, France, 199