890 research outputs found

    Effect on the electron EDM due to abelian gauginos in SUSY extra U(1) models

    Full text link
    The electric dipole moment of an electron (EDME) is investigated in the supersymmetric extra U(1) models. Neutralino sector is generally extended in these models and then the neutralino contribution will be important for the analysis of the EDME. Kinetic term mixings of abelian gauginos are taken into account in our analysis. Numerical results for the extra U(1) models show that the EDME can be affected by the extra U(1) in a certain range of soft supersymmetry breaking parameters even if the extra U(1) gauge boson is heavy. The EDME may be a clue to find an extended gauge structure in the supersymmetric models.Comment: 16 pages, latex, 3 figure

    Spin Physics at e^+e^- Colliders

    Get PDF
    A large number of measurements with polarized beams and/or spin analysis of final state particles has been performed at the e^+e^- colliders LEP and SLC, providing important information on the dynamics of high energy interactions. In this paper three subjects, for which the role of spin studies was particularly relevant, will be covered: the measurements of the electroweak couplings, the study of fragmentation dynamics and the search for physics beyond the Standard Model.Comment: 11 pages, Invited talk given at the International Workshop on Symmetry and Spin - Prague, Czech Republic, August 30 - September 5, 199

    Year in review 2008: Critical Care - sepsis

    Get PDF
    The present report highlights the most important papers appearing in Critical Care and other major journals about severe sepsis, the systemic inflammatory response and multiorgan dysfunction over the past year. A number of these clinical and laboratory studies will have a considerable impact on the sepsis research agenda for years to come. The steroid controversy, the debate over tight glycemic control, the colloid versus crystalloid issue, the value of selective decontamination of the digestive tract, the enlarging role of biomarkers, the value of genomics and rapid diagnostic techniques have all been prominently featured in recent publications. Basic research into novel predictive assays, genetic polymorphisms, and new molecular methods to risk-stratify and to determine treatment options for sepsis have occupied much of the Critical Care publications relating to sepsis pathophysiology in 2008. We will attempt to briefly summarize what we consider to be the most significant contributions to the sepsis literature over the last year, and their likely ramifications in the future, for critical care clinicians, clinical investigators and basic researchers alike

    Forward-backward multiplicity correlations and leakage parameter behaviour in asymmetric high energy collisions

    Full text link
    Continuing previous work, forward-backward multiplicity correlations are studied in asymmetric collisions in the framework of the weighted superposition mechanism of different classes of events. New parameters for the asymmetric clan distribution and for the particle leakage from clans in one hemisphere to the opposite one are introduced to effectively classify different classes of collisions. This tool should be used to explore forward-backward multiplicity correlations in AB and pA collisions in present and future experiments at RHIC and LHC.Comment: 14 pages, 2 figures, latex 2e with amsmat

    Unanswered Questions in the Electroweak Theory

    Full text link
    This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider. A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction of the electroweak theory is the existence of the Higgs boson, a weakly interacting spin-zero particle that is the agent of electroweak symmetry breaking, the giver of mass to the weak gauge bosons, the quarks, and the leptons. General arguments imply that the Higgs boson or other new physics is required on the TeV energy scale. Indirect constraints from global analyses of electroweak measurements suggest that the mass of the standard-model Higgs boson is less than 200 GeV. Once its mass is assumed, the properties of the Higgs boson follow from the electroweak theory, and these inform the search for the Higgs boson. Alternative mechanisms for electroweak symmetry breaking are reviewed, and the importance of electroweak symmetry breaking is illuminated by considering a world without a specific mechanism to hide the electroweak symmetry. For all its triumphs, the electroweak theory has many shortcomings. . . .Comment: 31 pages, 20 figures; prepared for Annual Review of Nuclear and Particle Science (minor changes

    Production of Triply Charmed Ωccc\Omega_{ccc} Baryons in e+e−e^+e^- Annihilation

    Full text link
    The total and differential cross sections for the production of triply charmed Ωccc\Omega_{ccc} baryons in e+e−e^{+}e^{-} annihilation are calculated at the ZZ-boson pole.Comment: 13 pages, 2 figure

    Uncertainties of the CJK 5 Flavour LO Parton Distributions in the Real Photon

    Full text link
    Radiatively generated, LO quark (u,d,s,c,b) and gluon densities in the real, unpolarized photon, calculated in the CJK model being an improved realization of the CJKL approach, have been recently presented. The results were obtained through a global fit to the experimental F2^gamma data. In this paper we present, obtained for the very first time in the photon case, an estimate of the uncertainties of the CJK parton distributions due to the experimental errors. The analysis is based on the Hessian method which was recently applied in the proton parton structure analysis. Sets of test parametrizations are given for the CJK model. They allow for calculation of its best fit parton distributions along with F2^gamma and for computation of uncertainties of any physical value depending on the real photon parton densities. We test the applicability of the approach by comparing uncertainties of example cross-sections calculated in the Hessian and Lagrange methods. Moreover, we present a detailed analysis of the chi^2 of the CJK fit and its relation to the data. We show that large chi^2/DOF of the fit is due to only a few of the experimental measurements. By excluding them chi^2/DOF approx 1 can be obtained.Comment: 28 pages, 8 eps figures, 2 Latex figures; FORTRAN programs available at http://www.fuw.edu.pl/~pjank/param.html; table 10, figure 10 and section 6 correcte

    The MSSM fine tuning problem: a way out

    Full text link
    As is well known, electroweak breaking in the MSSM requires substantial fine-tuning, mainly due to the smallness of the tree-level Higgs quartic coupling, lambda_tree. Hence the fine tuning is efficiently reduced in supersymmetric models with larger lambda_tree, as happens naturally when the breaking of SUSY occurs at a low scale (not far from the TeV). We show, in general and with specific examples, that a dramatic improvement of the fine tuning (so that there is virtually no fine-tuning) is indeed a very common feature of these scenarios for wide ranges of tan(beta) and the Higgs mass (which can be as large as several hundred GeV if desired, but this is not necessary). The supersymmetric flavour problems are also drastically improved due to the absence of RG cross-talk between soft mass parameters.Comment: 28 pages, 9 PS figures, LaTeX Published versio

    Copy Number Variants Are Ovarian Cancer Risk Alleles at Known and Novel Risk Loci

    Get PDF
    Background Known risk alleles for epithelial ovarian cancer (EOC) account for approximately 40% of the heritability for EOC. Copy number variants (CNVs) have not been investigated as EOC risk alleles in a large population cohort. Methods Single nucleotide polymorphism array data from 13 071 EOC cases and 17 306 controls of White European ancestry were used to identify CNVs associated with EOC risk using a rare admixture maximum likelihood test for gene burden and a by-probe ratio test. We performed enrichment analysis of CNVs at known EOC risk loci and functional biofeatures in ovarian cancer-related cell types. Results We identified statistically significant risk associations with CNVs at known EOC risk genes; BRCA1 (P-EOC = 1.60E-21; OREOC = 8.24), RAD51C (Phigh-grade serous ovarian cancer [HGSOC] = 5.5E-4; odds ratio [OR](HGSOC) = 5.74 del), and BRCA2 (P-HGSOC = 7.0E-4; ORHGSOC = 3.31 deletion). Four suggestive associations (P < .001) were identified for rare CNVs. Risk-associated CNVs were enriched (P < .05) at known EOC risk loci identified by genome-wide association study. Noncoding CNVs were enriched in active promoters and insulators in EOC-related cell types. Conclusions CNVs in BRCA1 have been previously reported in smaller studies, but their observed frequency in this large population-based cohort, along with the CNVs observed at BRCA2 and RAD51C gene loci in EOC cases, suggests that these CNVs are potentially pathogenic and may contribute to the spectrum of disease-causing mutations in these genes. CNVs are likely to occur in a wider set of susceptibility regions, with potential implications for clinical genetic testing and disease prevention.Peer reviewe

    Questions and Remarks About Clans in Multiparticle Dynamics

    Get PDF
    The fact that several important effects in multiparticle dynamics, on which QCD has not yet satisfactory predictions, have been interpreted in terms of the validity of negative binomial (Pascal) regularity and related clan properties at the level of simpler substructures, raises intriguing questions on clan properties in all classes of collisions, the main one being whether clans are observable objects or merely a mathematical concept. We approach this problem by studying clan masses and rapidity distributions in each substructure for e+e- annihilation and hh collisions, and find that such properties can indeed characterise the different components. These results support the idea that clans could be observable, a challenging problem for future experiments.Comment: 11 pages; 3 figures; latex 2e and amsmat
    • 

    corecore