ATLAS

Abstract:

Inclusive Ks⁰Ks⁰ production in deep inelastic ep scattering at HERA has been studied with the ZEUS detector using an integrated luminosity of 120 pb^-1. Two states are observed at masses of 1537-8^-9 MeV and 1726 ± 7 MeV, as well as an enhancement around 1300 MeV. The state at 1537 MeV is consistent with the well established f′2(1525). The state at 1726 MeV may be the glueball candidate f0(1710). However, it's width of 38 -14^-20 MeV is narrower than 125 ± 10 MeV observed by previous experiments for the f0(1710). © 2003 Elsevier B.V. All rights reserved.

Abstract:

Some of the most recent results on jet production at HERA are reviewed. The measurements are confronted with predictions from next-to-leading order Quantum Chromodynamics. In regions where uncertainties are small, the strong coupling, αs, has been extracted. Other topics of current interest are also highlighted.

Abstract:

We present the results of a search for the production of new particles decaying into two jets in [Formula Presented]collisions at [Formula Presented] using the DØ 1992–1995 data set corresponding to [Formula Presented] We exclude at the 95% confidence level the production of excited quarks [Formula Presented] with masses below 775 GeV/[Formula Presented] the most restrictive limit to date. We also exclude standard-model-like [Formula Presented][Formula Presented] bosons with masses between 300 and 800 GeV/[Formula Presented](400 and 640 GeV/[Formula Presented] A [Formula Presented]boson with mass [Formula Presented] has been excluded by previous measurements, and our lower limit is therefore the most stringent to date. © 2004 The American Physical Society.

Abstract:

Charge collection measurements performed on heavily irradiated p-spray dofz pixel sensors with a grazing angle hadron beam provide a sensitive determination of the electric field within the detectors. The data are compared with a complete charge transport simulation of the sensor which includes signal trapping and charge induction effects. A linearly varying electric field based upon the standard picture of a constant type-inverted effective doping density is inconsistent with the data. A two-trap double junction model implemented in ISE TCAD software can be tuned to produce a doubly-peaked electric field which describes the data reasonably well at two different fluences. The modeled field differs somewhat from previous determinations based upon the transient current technique. The model can also account for the level of signal trapping observed in the data. © 2004 IEEE.

Abstract:

For comparison of inclusive jet cross sections measured at hadron-hadron colliders to next-to-leading order (NLO) parton-level calculations, the energy deposited in the jet cone by spectator parton interactions must first be subtracted. The assumption made at the Tevatron is that the spectator parton interaction energy is similar to the ambient level measured in minimum bias events. In this paper, we test this assumption by measuring the ambient charged track momentum in events containing large transverse energy jets at [Formula Presented] and [Formula Presented] and comparing this ambient momentum with that observed both in minimum bias events and with that predicted by two Monte Carlo models. Two cones in [Formula Presented] space are defined, at the same pseudorapidity, [Formula Presented], as the jet with the highest transverse energy ([Formula Presented]), and at [Formula Presented] in the azimuthal direction, [Formula Presented]. The total charged track momentum inside each of the two cones is measured. The minimum momentum in the two cones is almost independent of [Formula Presented] and is similar to the momentum observed in minimum bias events, whereas the maximum momentum increases roughly linearly with the jet [Formula Presented] over most of the measured range. This study was carried out using data from the CDF detector taken during Run 1 (1994-1995). The study will help improve the precision of comparisons of jet cross section data and NLO perturbative QCD predictions. The distribution of the sum of the track momenta in the two cones is also examined for five different [Formula Presented] bins. The HERWIG and PYTHIA Monte Carlo generators are reasonably successful in describing the data, but neither can describe completely all of the event properties. © 2004 The American Physical Society.