26 research outputs found

    Electro-Magnetic Nucleon Form Factors and their Spectral Functions in Soliton Models

    Full text link
    It is demonstrated that in simple soliton models essential features of the electro-magnetic nucleon form factors observed over three orders of magnitude in momentum transfer tt are naturally reproduced. The analysis shows that three basic ingredients are required: an extended object, partial coupling to vector mesons, and relativistic recoil corrections. We use for the extended object the standard skyrmion, one vector meson propagator for both isospin channels, and the relativistic boost to the Breit frame. Continuation to timelike tt leads to quite stable results for the spectral functions in the regime from the 2- or 3-pion threshold to about two rho masses. Especially the onset of the continuous part of the spectral functions at threshold can be reliably determined and there are strong analogies to the results imposed on dispersion theoretic approaches by the unitarity constraint.Comment: 24 pages, (RevTeX), 5 PS-figures; Data points in fig.2 and corresponding references added. Final version, to be published in Z.Physik

    Classical skyrmions in SU(N)/SO(N) cosets

    Full text link
    We construct the skyrmion solutions appearing in the coset spaces SU(N)/SO(N) for N > 2 and compute their classical mass. For N = 3, the third homotopy group pi_3(SU(3)/SO(3)) = Z_4 implies the existence of two distinct solutions: the skyrmion of winding number two has spherical symmetry and is found to be the lightest non-trivial field configuration; the skyrmion and antiskyrmion of winding number plus and minus one are slightly heavier and of toroidal shape. For N >= 4, there is only one skyrmion since the third homotopy group is Z_2. It is found to have spherical symmetry and is significantly lighter than the N = 3 solutions.Comment: 14 pages, 3 figures; v2: discussion improve

    Maternal depressive symptoms, and not anxiety symptoms, are associated with positive mother–child reporting discrepancies of internalizing problems in children: a report on the TRAILS Study

    Get PDF
    Maternal internalizing problems affect reporting of child’s problem behavior. This study addresses the relative effects of maternal depressive symptoms versus anxiety symptoms and the association with differential reporting of mother and child on child’s internalizing problems. The study sample comprised a cohort of 1,986 10- to 12-year-old children and their mothers from the Dutch general population in a cross sectional setup. Children’s internalizing problems were assessed with the DSM-IV anxiety and affective problem scales of the Child Behavior Checklist (CBCL) and the Youth Self-Report (YSR). Current maternal internalizing problems were assessed with the depressive and anxiety symptom scales of the Depression Anxiety Stress Scale (DASS), while the TRAILS Family History Interview (FHI) measured lifetime maternal depression and anxiety. Results show that current and lifetime maternal depressive symptoms were associated with positive mother–child reporting discrepancies (i.e. mothers reporting more problems than their child). Considering the small amount of variance explained, we conclude that maternal depressive symptoms do not bias maternal reporting on child’s internalizing problems to a serious degree. Studies concerning long term consequences of mother–child reporting discrepancies on child’s internalizing problems are few, but show a risk for adverse outcome. More prognostic research is needed

    QCD and strongly coupled gauge theories : challenges and perspectives

    Get PDF
    We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.Peer reviewe

    General attitudes towards marriage scale: psychometric properties in Malaysian adolescents of divorced families

    Get PDF
    Attitudes towards marriage in adolescence may influence the relationship quality in later years. There exist many measures of attitudes towards marriage which were validated among adolescents from two-parent family in the Western context. There is a need to validate measure of attitudes towards marriage in different countries. This study examined the psychometric properties of the Malay version of general attitudes towards marriage scale in a sample of 480 adolescents from divorced families in Malaysia. Exploratory factor analysis yielded a two-factor structure of general attitudes towards marriage scale, which explained for 60% of the variance. Additionally, the two-factor structure of general attitudes towards marriage scale demonstrated good fit to data in the confirmatory factor analysis (non-normed fit index = .941, comparative fit index = .958, root mean square error of estimation = .087, and χ 2/df = 4.615). Overall, the general attitudes towards marriage scale exhibited good internal consistency (α = .901), which supports the reliability of the instrument. The significant relationships between general attitudes towards marriage scale and other constructs also provided evidences to the convergent validity (r = .761, p < .001 with intent to marry, r = −.170, p < .001 with overt inter-parental conflict, and r = .523, p < .001 with mother–adolescent relationship). Significant gender difference was found in the report of general attitudes towards marriage scale (t = −2.265, p < .05). Thus, the translated general attitudes towards marriage scale is a reliable, valid, and practical instrument to measure attitudes towards marriage among Malaysian adolescents in divorced family setting

    Phenotypic and measurement influences on heritability estimates in childhood ADHD

    Full text link
    corecore