10,994 research outputs found

    Towards an Understanding of the New Charm and Charm-Strange Mesons

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    The observation of the D_{sJ}^*(2317), D_{sJ}(2460), and SELEX D^*_{sJ}(2632) states with properties differing considerably from what was expected has led to a renewed interest in hadron spectroscopy. In addition to these states, non-strange partners of the D_{sJ} states have also been observed. Understanding the D_0^* and D_1' states can provide important insights into the D_{sJ} states. In this contribution I examine quark model predictions for the D_0^* and D_1' states and discuss experimental measurements that can shed light on them. I find that these states are well described as the broad, j=1/2 non-strange charmed P-wave mesons. In the latter part of this writeup I discuss the c bar{s} possibilities for the SELEX D^*_{sJ}(2632) and measurements that can shed light on it.Comment: Talk presented at the 1st Meeting of the APS Topical Group on Hadronic Physics (Fermilab, Oct 24-26, 2004). 4 pages uses jpcon

    Some Limited-Interest Problems

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    Some Limited-Interest Problems

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    The asymptotic probability distribution of identified black-box transfer function models is studied. The main contribution is that we derive variance expressions for the real and imaginary parts of the identified models that are asymptotic in both the number of measurements and the model order. These expressions are considerably simpler than the corresponding ones that hold for fixed model orders, and yet they frequently approximate the true covariance well already with quite modest model orders. We illustrate the relevance of the asymptotic expressions by using them to compute uncertainty regions for the frequency response of an identified model

    Comment on ZZ''s and the H1 and ZEUS High Q2Q^2 Anomalies

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    We investigate the effects of extra neutral gauge bosons on the high Q2Q^2 region of the e+pe+Xe^+p \to e^+ X cross section at s=300\sqrt{s}=300 GeV. We found that the only models with electroweak strength coupling, typical of extended gauge theories, that give a better fit to the H1 and ZEUS high Q2Q^2 data than the standard model, are ruled out by existing data from the Tevatron. From general scaling arguments, using the allowed contact interactions, the only allowed models with ZZ''s would be those with strong couplings although even in this case the statistical evidence is not compelling.Comment: Latex file uses revtex version 3, epsfig, 1 postscript figure is attache

    Probing Contact Interactions at High Energy Lepton Colliders

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    Fermion compositeness and other new physics can be signalled by the presence of a strong four-fermion contact interaction. Here we present a study of qq\ell\ell qq and \ell\ell\ell'\ell' contact interactions using the reactions: ++,bbˉ,ccˉ\ell^+ \ell^- \to \ell'^+\ell'^-,b\bar b, c\bar c at future e+ee^+e^- linear colliders with s=0.55\sqrt s=0.5-5 TeV and μ+μ\mu^+\mu^- colliders with s=0.5,4\sqrt s=0.5,4 TeV. We find that very large compositeness scales can be probed at these machines and that the use of polarized beams can unravel their underlying helicity structure.Comment: 12 pg, to appear in the {\it Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics - Snowmass96}, Snowmass, CO, 25 June - 12 July, 199
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