arXiv subjects
Publications and source records attributed to Raimund Ströhmer.
In order to stimulate new engagement and trigger some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an $e^+e^-$ Higgs / Top / Electroweak factory, we propose to define a set of focus topics. The general reasoning and the proposed topics are described in this document.
The Micro-Pattern Gaseous Detectors (MPGD) have been widely adopted in nuclear and particle physics experiments, for their fast response and other excellent characteristics. To achieve the required signal strength and detection efficiency, sometimes they are operated at a high voltage range. This often challenges the limit of high voltage stability of the detector. Discharge in gaseous detectors is a complex process and involves several responsible factors. The microscopic geometrical structures of the MPGDs may itself sometimes induce discharges. In this study, we are numerically investigating the discharge phenomena in non-resistive Micromegas. Within the COMSOL framework, a 3-dimensional model is developed to observe the occurrence and the development of discharge in Micromegas. The effect of space charge has been taken into account in the calculation. The model allows to vary the geometrical parameters of the detector as well as to study the effects of gas impurities and a different number of primary charges.
We report on studies of Bose-Einstein correlations and color reconnection in hadronic W pair production at LEP. Bose-Einstein correlations between identical particles from the decay of different W's are studied by comparing the particle correlation in hadronic W pair decays to those in events which are constructed from the combination of the hadronic parts of two events where one of the Ws decays leptonicaly. The LEP combined result of the strength of the effect is consistent with zero and can be used to limit the systematic uncertainty due to Bose-Einstein correlations on the W mass measurements. Color reconnection is expected to affect the production of particles in hadronic decays of W pairs. Measurements of inclusive charged particle multiplicities, and of their angular distribution with respect to the four jet axes of the events, are used to test models of color reconnection. The results are both consistent with models without color reconnection and models with moderate color reconnection. They can be used to exclude more extreme models of color reconnection and thereby limit the uncertainty due to color reconnection on the W mass measurement.
We present a preliminary measurement of the inclusive jet cross-sections based on an integrated luminosity of 378 pb^{-1} acquired with the D0 detector between 2002 and 2004 at a center of mass energy of \sqrt{s}=1.96 TeV and a measurement of azimuthal dijet decorrelations based on an integrated luminosity of 150 pb^{-1}. The cross section measurements are based on an iterative cone algorithm with a cone size of R=0.7. They are performed in two rapidity bins between 0.0 and 0.8. The measurements are in good agreement with next to leading order calculations. The azimuthal angle between the two leading jets is sensitive to higher order QCD effects. The measurement of dijet azimuthal decorrelations therefore probes these effects without explicitly reconstructing more than two jets. Except for large azimuthal angles where soft effects are important the measurements are well described by the next to leading order perturbation theory.
This article summarizes the status of the Tevatron Run II searches for leptoquarks in $p\bar{p}$ collisions at $\sqrt{s}=1.96 $ TeV. The analyses discussed use datasets with integrated luminosities ranging from 72 pb$^{-1}$ to 200 pb$^{-1}$.}
We review the precision measurement of the mass of the W-boson at LEP. We discuss the techniques used by the four LEP experiments to determine the mass of the W-boson as well as the major sources of systematic uncertainty. The measurement of the WW and ZZ cross-sections are presented.
We review the precision measurement of the mass and couplings of the W Boson at LEP. The total and differential W+W- cross section is used to extract the WWZ and WWgamma couplings. We discuss the techniques used by the four LEP experiments to determine the W mass in different decay channels, and present the details of methods used to evaluate the sources of systematic uncertainty.