486 research outputs found

    Interplay between perturbative and non-perturbative effects in the stealthy Higgs model

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    We study corrections to electroweak precision variables in a model with strongly interacting singlet Higgs particles.Comment: 31 pages, Latex, 11 figure

    Resonance in Strong WW Rescattering in Massive SU(2) Gauge Theory

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    We investigate the effects of WW rescattering through strong anomalous four-vector boson couplings. In the I=1, J=1 channel, we find a resonance with a mass of approximately 200 GeV and a width of less than 12 GeV. In an application to pion physics we find a small correction to the KSRF relation.Comment: 21 pages, extended discussion, some minor change

    Density-metric unimodular gravity:vacuum spherical symmetry

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    We analyze an alternative theory of gravity characterized by metrics that are tensor density of rank(0,2)and weight-1/2.The metric compatibility condition is supposed to hold. The simplest expression for the action of gravitational field is used.Taking the metric and trace of connections as dynamical variables,the field equations in the absence of matter and other kinds of sources are derived.The solutions of these equations are obtained for the case of vacuum static spherical symmetric spacetime.The null geodesics and advance of perihelion of ellipes are discussed.We confirm a subclass of solutions is regular for r>0 and there is no event horizon while it is singular at r=0.Comment: 15 pages,no,figures,typos corrected,new section added,published versio

    Gravitational anomaly and fundamental forces

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    I present an argument, based on the topology of the universe, why there are three generations of fermions. The argument implies a preferred gauge group of SU(5), but with SO(10) representations of the fermions. The breaking pattern SU(5) to SU(3)xSU(2)xU(1) is preferred over the pattern SU(5) to SU(4)xU(1). On the basis of the argument one expects an asymmetry in the early universe microwave data, which might have been detected already.Comment: Contribution to the 2nd School and Workshop on Quantum Gravity and Quantum Geometry. Corfu, september 13-20 2009. 10 page

    Heavy Fermion Screening Effects and Gauge Invariance

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    We show that the naively expected large virtual heavy fermion effects in low energy processes may be screened if the process under consideration contains external gauge bosons constrained by gauge invariance. We illustrate this by a typical example of the process γγ→bbˉ\gamma\gamma\to b \bar{b}. Phenomenological implications are also briefly indicated.Comment: a miss-print fixed, 7 pages, LaTex, no figure

    Prognosis and prognostic factors of patients with mesothelioma:A population-based study

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    BACKGROUND: It is important to regularly update survival estimates of patients with malignant mesothelioma as prognosis may vary according to epidemiologic factors and diagnostic and therapeutic management. METHODS: We assessed overall (baseline) survival as well as related prognostic variables in a large cohort of 1353 patients with a confirmed diagnosis of malignant mesothelioma between 2005 and 2008. RESULTS: About 50% of the patients were 70 years or older at diagnosis and the median latency time since start of asbestos exposure was 49 years. One year after diagnosis, 47% of the patients were alive, 20% after 2 years and 15% after 3 years. Prognostic variables independently associated with worse survival were: older age (HR=1.04 per year 95% CI (1.03–1.06)), sarcomatoid subtype (HR=2.45 95% CI (2.06–2.90)) and non-pleural localisation (HR=1.67 95% CI (1.26–2.22)). CONCLUSION: Survival of patients with malignant mesothelioma is still limited and depends highly on patient age, mesothelioma subtype and localisation. In addition, a substantial part of the patients had a long latency time between asbestos exposure and diagnosis

    Mini-Proceedings of the 15th meeting of the Working Group on Rad. Corrections and MC Generators for Low Energies

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    The mini-proceedings of the 15th Meeting of the "Working Group on Rad. Corrections and MC Generators for Low Energies" held in Mainz on April 11, 2014, are presented. These meetings, started in 2006, have as aim to bring together experimentalists and theorists working in the fields of meson transition form factors, hadronic contributions to (g−2)μ(g-2)_\mu and the effective fine structure constant, and development of Monte Carlo generators and Radiative Corrections for precision e+e- and tau physics.Comment: 21 pages, 7 contributions. Editors: S. E. Mueller and G. Venanzon

    Incomplete quality of life data in lung transplant research: comparing cross sectional, repeated measures ANOVA, and multi-level analysis

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    BACKGROUND: In longitudinal studies on Health Related Quality of Life (HRQL) it frequently occurs that patients have one or more missing forms, which may cause bias, and reduce the sample size. Aims of the present study were to address the problem of missing data in the field of lung transplantation (LgTX) and HRQL, to compare results obtained with different methods of analysis, and to show the value of each type of statistical method used to summarize data. METHODS: Results from cross-sectional analysis, repeated measures on complete cases (ANOVA), and a multi-level analysis were compared. The scores on the dimension 'energy' of the Nottingham Health Profile (NHP) after transplantation were used to illustrate the differences between methods. RESULTS: Compared to repeated measures ANOVA, the cross-sectional and multi-level analysis included more patients, and allowed for a longer period of follow-up. In contrast to the cross sectional analyses, in the complete case analysis, and the multi-level analysis, the correlation between different time points was taken into account. Patterns over time of the three methods were comparable. In general, results from repeated measures ANOVA showed the most favorable energy scores, and results from the multi-level analysis the least favorable. Due to the separate subgroups per time point in the cross-sectional analysis, and the relatively small number of patients in the repeated measures ANOVA, inclusion of predictors was only possible in the multi-level analysis. CONCLUSION: Results obtained with the various methods of analysis differed, indicating some reduction of bias took place. Multi-level analysis is a useful approach to study changes over time in a data set where missing data, to reduce bias, make efficient use of available data, and to include predictors, in studies concerning the effects of LgTX on HRQL

    Corrections to oblique parameters induced by anomalous vector boson couplings

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    We study quadratically divergent radiative corrections to the oblique parameters at LEP1 induced by non-standard vector boson self-couplings. We work in the Stueckelberg formalism and regulate the divergences through a gauge-invariant higher derivative scheme. Using consistency arguments together with the data we find a limit on the anomalous magnetic moment Delta kappa of the W-boson, |Delta kappa| <= 0.26.Comment: 32 pages, LaTeX; cross reference corrected, minor beautifications, version to be published in Phys.Rev.
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