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Tau jet signals for supersymmetry at the Tevatron

Description: The authors present a more detailed account of the study (hep-ph/9903238) for the supersymmetry reach of the Tevatron in channels with isolated leptons and identified tau jets. They review the theoretical motivations for expecting such signatures, and describe the relevant parameter space in the minimal supergravity and the minimal gauge-mediated models. With explicit Monte Carlo simulations they then show that for certain parameter ranges, channels with two leptons and one tau jet offer a better reach in Run 2 than the clean trilepton signal. They emphasize that improving on tau ID is an important prerequisite for successful searches in multiple tau jet channels. Finally, they discuss some triggering issues.
Date: January 25, 2000
Creator: Lykken, J.D. & Matchev, K.T.
Partner: UNT Libraries Government Documents Department

A recipe for the construction of confidence limits

Description: In this note, the authors present the recipe recommended by the Search Limits Committee for the construction of confidence intervals for the use of D0 collaboration. In another note, currently in preparation, they present the rationale for this recipe, a critique of the current literature on this topic, and several examples of the use of the method. This note is intended to fill the need of the collaboration to have a reference available until the more complete note is finished. Section 2 introduces the notation used in this note, and Section 3 contains the suggested recipe.
Date: April 12, 2000
Creator: al., Iain A Bertram et
Partner: UNT Libraries Government Documents Department

CP violation and rare decays

Description: After a brief essay on the current state of particle physics and possible approaches to the opportunities that have presented themselves, the author summarizes the contributions to the Third Workshop on Physics and Detectors for DA{Phi}NE that deal with CP Violation and Rare Decays.
Date: January 24, 2000
Creator: Quigg, C.
Partner: UNT Libraries Government Documents Department

Measurement of sin2{beta} from J/{psi} K{sub s} decays

Description: The CP-violating parameter sin 2{beta} is directly measured using 110 pb{sup {minus}1} of data accumulated with the CDF detector at the Fermilab {anti p}p Tevatron collider operating at {radical}s = 1.8 TeV. The signal consists of 395 {+-} 31 B{sub d}{sup 0} {r{underscore}arrow} J/{psi} K{sub s} events. Three tagging methods are used to identify the type of B meson at production (B{sub d}{sup 0} or {anti B}{sub d}{sup 0}). From the CP asymmetry, sin 2{beta} is measured to be 0.79 {sub {minus}0.44}{sup +0.41}, consistent with Standard Model predictions. Sin 2{beta} is in the interval 0 {lt} sin2{beta} {lt} 1 at the 93% confidence level.
Date: January 24, 2000
Creator: Blocker, C.A.
Partner: UNT Libraries Government Documents Department

Run II jet physics: Proceedings of the Run II QCD and weak boson physics workshop

Description: The Run II jet physics group includes the Jet Algorithms, Jet Shape/Energy Flow, and Jet Measurements/Correlations subgroups. The main goal of the jet algorithm subgroup was to explore and define standard Run II jet finding procedures for CDF and D0. The focus of the jet shape/energy flow group was the study of jets as objects and the energy flows around these objects. The jet measurements/correlations subgroup discussed measurements at different beam energies; {alpha}{sub S} measurements; and LO, NLO, NNLO, and threshold jet calculations. As a practical matter the algorithm and shape/energy flow groups merged to concentrate on the development of Run II jet algorithms that are both free of theoretical and experimental difficulties and able to reproduce Run I measurements. Starting from a review of the experience gained during Run I, the group considered a variety of cone algorithms, and K{sub T} algorithms. The current understanding of both types of algorithms, including calibration issues, are discussed in this report along with some preliminary experimental results. The jet algorithms group recommends that CDF and D0 employ the same version of both a cone algorithm and a K{sub T} algorithm during Run II. Proposed versions of each type of algorithm are discussed. The group also recommends the use of full 4-vector kinematic variables whenever possible. The recommended algorithms attempt to minimize the impact of seeds in the case of the cone algorithm and preclustering in the case of the K{sub T} algorithm. Issues regarding precluster definitions and merge/split criteria require further study.
Date: May 11, 2000
Creator: al., Gerald C. Blazey et
Partner: UNT Libraries Government Documents Department

Neutrino oscillation appearance experiment using nuclear emulsion and magnetized iron

Description: This report describes an apparatus that could be used to measure both the identity and charge of an outgoing lepton in a charged current neutrino interaction. This capability in a massive detector would allow the most comprehensive set of neutrino oscillation physics measurements. By measuring the six observable transitions between initial and final state neutrinos, one would be able to measure all elements of the neutrino mixing matrix, as well as search for CP violation, and matter effects. If the measured matrix is not unitary, then one would also have an unambiguous determination of sterile neutrinos. Emulsion is considered as the tracking medium, and different techniques are discussed for the application of a magnetic field.
Date: January 24, 2000
Creator: Harris, D.A. & Para, A.
Partner: UNT Libraries Government Documents Department

Setting limits and making discoveries in CDF

Description: This paper presents the statistical methods used in setting limits and discovery significances in the search for new particles in the CDF experiment at the Fermilab Tevatron. For single-channel counting experiments the collaboration employs the classical Helene formula, with Bayesian integration over systematic uncertainties in the signal acceptance and background. For more complex cases such as spectral fits and combining channels, likelihood-based methods are used. In the discoveries of the top quark and B{sub c} meson, the significance was estimated from the probability of the null hypothesis, using toy Monte Carlo methods. Lastly, in the recent SUSY/Higgs Workshop the Higgs Working Group used a method of combining channels and experiments based on the calculation of the joint likelihood for a particular experimental outcome, and averaging over all possible outcomes.
Date: May 15, 2000
Creator: Conway, J.
Partner: UNT Libraries Government Documents Department