198,257 research outputs found

    B Decay Studies at Cleo

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    Weak decays of heavy flavored hadrons are sensitive probes of several facets of the Standard Model. In particular the experimental study of B meson semileptonic decaysis starting to pin down the quark mixing parameters in the Cabibbo Kobayashi Maskawa matrix. In addition, some features of the non--perturbative regime of the strong interaction are probed by these decays. New results from the CLEO experiment at the CESR electron-positron collider, based on a data sample of up to 3.5 inverse femtobarn, provide crucial information on both of these aspects of heavy flavor phenomenology.Comment: 25 pages, 11 figures, Late

    The theory and phenomenology of perturbative QCD based jet quenching

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    The study of the structure of strongly interacting dense matter via hard jets is reviewed. High momentum partons produced in hard collisions produce a shower of gluons prior to undergoing the non-perturbative process of hadronization. In the presence of a dense medium this shower is modified due to scattering of the various partons off the constituents in the medium. The modified pattern of the final detected hadrons is then a probe of the structure of the medium as perceived by the jet. Starting from the factorization paradigm developed for the case of particle collisions, we review the basic underlying theory of medium induced gluon radiation based on perturbative Quantum Chromo Dynamics (pQCD) and current experimental results from Deep Inelastic Scattering on large nuclei and high energy heavy-ion collisions, emphasizing how these results constrain our understanding of energy loss. This review contains introductions to the theory of radiative energy loss, elastic energy loss, and the corresponding experimental observables and issues. We close with a discussion of important calculations and measurements that need to be carried out to complete the description of jet modification at high energies at future high energy colliders.Comment: 78 pages, 24 figures, submitted to prog. part. nucl. phy

    Low x particle spectra in the Modified Leading Logarithm Approximation

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    We show that the higher moments of the evolution obtained from the Modified Leading Logarithm Approximation may be regarded as spurious higher order terms in perturbation theory, and that neglecting them leads to a good description of the data around and above the peak in ξ=ln(1/x)\xi=\ln (1/x). Furthermore, we use this study of the moments to show that at high energy the Limiting Spectrum with Local Parton-Hadron Duality may also be derived from the Modified Leading Logarithm Approximation without any non-perturbative assumptions.Comment: Submitted to Eur. Phys. J.,

    Complete LEP Data: Status of Higgs Boson Searches

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    The LEP experiments completed data-taking in November 2000. New preliminary combined results of the four LEP experiments ALEPH, DELPHI, L3 and OPAL are presented for various Higgs boson searches.Comment: 9 pages, 12 figures. Proc. Third Int.Conference on Non-Accelerator New Physics, NANP-01, Moscow, 200

    The Delphi: An Underutilized Method of Scholarly and Practical Research for a Public Relations Field in Transition

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    This paper introduces, analyzes, and explains the Delphi method of research, particularly as it applies to certain aspects of the public relations industry. The Delphi technique became known some fifty years ago when the Rand Corporation used it extensively for forecasting. Since then, scholars and forecasters have used it periodically for early, qualitative explorations into complex issues or domains. The overall purpose of the Delphi is to facilitate formal discussion among selected experts in a given domain around a particular topic; it is particularly useful when those experts cannot easily come together in one place. The method encourages the sharing of diverging worldviews over a few “rounds” or iterations in the hope that the views may converge into some direction around the given topic. For this reason, the Delphi has often been used in situations or environments that tend to be somewhat ambiguous and where interviews and surveys are neither timely nor appropriate. Public relations scholars started incorporating the Delphi method into their research in the late 1980s, and the technique has since been employed to explore broad-ranging issues among experts on at least seven or eight occasions. It has also been used to explore ethical norms. However, public relations literature contains little discussion about the technique and its possible applications or implications for developing knowledge in the field. This paper, then, is intended to dissect the Delphi method so as to offer guidance to public relations scholars who may wish to use it in future studies. The authors, both of whom have conducted Delphi studies, believe that the method is valuable in examining topics that are emerging or underdeveloped in the field; however, certain precautions are necessary in order to ensure that the research achieves the desired effects. The paper is created through a literature review of similar articles on Delphi studies in other domains, notably health communications, followed by an examination of some studies conducted to advance issues in public relations. The authors explore the most appropriate situations for using a Delphi and list the benefits and disbenefits of different aspects or applications of the method. They trace the evolution of Delphi research from its early roots into the era of the Internet and social media, which offer new tools for increasing the number of respondents and moving through the Delphi process more quickly than could previously be done. In advancing such an examination of the Delphi, this paper should be a useful addition to emerging public relations literature
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