Subjet distributions in deep inelastic scattering at HERA

European Physical Journal C (Impact Factor: 5.25). 63(4):527-548. DOI: 10.1140/epjc/s10052-009-1090-3

ABSTRACT Subjet distributions were measured in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 81.7pb−1. Jets were identified using the k

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 ycuty_{\rm cut}. Measurements of subjet distributions for jets with exactly two subjets for ycut=0.05y_{\rm cut}=0.05 are presented as functions of observables sensitive to the pattern of parton radiation and to the colour coherence between
the initial and final states. Perturbative QCD predictions give an adequate description of the data.

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    ABSTRACT: Hadronic jets in electron–proton collisions at HERA have been used for some considerable time as a tool for tests of the theory of strong interactions, quantum chromodynamics. Using jet final states, basic concepts like the factorisation ansatz for cross-section calculations, the perturbative approach to the cross section and the universality of the proton parton distribution functions can be examined. More concretely, jet measurements provide ready access to the strong coupling of QCD, α s , and to the parton distributions. In this report, an overview of jet results from the HERA experiments H1 and ZEUS and their interpretation is given together with a description of the theoretical foundations of jet physics in electron–proton collisions and of the experimental environment at HERA. Special emphasis is put on extractions of α s values and on the influence of jet data on fits of the proton parton distribution functions. Where useful, the HERA results are also discussed in the light of results from other colliders like LEP, the Tevatron or the LHC. The central message from these studies is that QCD does not only describe most of the measurements very well, but that QCD at HERA has achieved the status of a precision theory. On the other hand it is shown that further understanding of problematic issues relies critically on theoretical progress in the form of improved models or of increased precision in analytical calculations.
    European Physical Journal C 72(7). · 5.25 Impact Factor
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    ABSTRACT: We present the report of the hadronic working group of the BOOST2010 workshop held at the University of Oxford in June 2010. The first part contains a review of the potential of hadronic decays of highly boosted particles as an aid for discovery at the LHC and a discussion of the status of tools developed to meet the challenge of reconstructing and isolating these topologies. In the second part, we present new results comparing the performance of jet grooming techniques and top tagging algorithms on a common set of benchmark channels. We also study the sensitivity of jet substructure observables to the uncertainties in Monte Carlo predictions.
    European Physical Journal C 71(6):1-19. · 5.25 Impact Factor

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