444 research outputs found

    Analytic structure of meson propagators in the proper-time regularized Nambu--Jona-Lasinio model

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    We analyze the analytic structure of meson propagators in the Nambu--Jona-Lasinio model with a proper-time regulator. We show that the regulator produces unphysical complex singularities. As a result the naive use of the Wick rotation is no longer allowed. Formulas involving integration over mesonic momenta, such as meson-loop contributions or dispersion relations for meson Green's functions, cannot be written in usual forms.Comment: revised versio

    Automated Retrieval of Non-Engineering Domain Solutions to Engineering Problems

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    Organised by: Cranfield UniversityBiological inspiration for engineering design has occurred through a variety of techniques such as creation and use of databases, keyword searches of biological information in natural-language format, prior knowledge of biology, and chance observations of nature. This research focuses on utilizing the reconciled Functional Basis function and flow terms to identify suitable biological inspiration for function based design. The organized search provides two levels of results: (1) associated with verb function only and (2) narrowed results associated with verb-noun (function-flow). A set of heuristics has been complied to promote efficient searching using this technique. An example for creating smart flooring is also presented and discussed.Mori Seiki – The Machine Tool Compan

    Emotional Insecurity about the Community: A Dynamic, Within-Person Mediator of Child Adjustment in Contexts of Political Violence

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    AbstractOver 1 billion children worldwide are exposed to political violence and armed conflict. The current conclusions are qualified by limited longitudinal research testing sophisticated process-oriented explanatory models for child adjustment outcomes. In this study, consistent with a developmental psychopathology perspective emphasizing the value of process-oriented longitudinal study of child adjustment in developmental and social–ecological contexts, we tested emotional insecurity about the community as a dynamic, within-person mediating process for relations between sectarian community violence and child adjustment. Specifically, this study explored children's emotional insecurity at a person-oriented level of analysis assessed over 5 consecutive years, with child gender examined as a moderator of indirect effects between sectarian community violence and child adjustment. In the context of a five-wave longitudinal research design, participants included 928 mother–child dyads in Belfast (453 boys, 475 girls) drawn from socially deprived, ethnically homogenous areas that had experienced political violence. Youth ranged in age from 10 to 20 years and were 13.24 (SD= 1.83) years old on average at the initial time point. Greater insecurity about the community measured over multiple time points mediated relations between sectarian community violence and youth's total adjustment problems. The pathway from sectarian community violence to emotional insecurity about the community was moderated by child gender, with relations to emotional insecurity about the community stronger for girls than for boys. The results suggest that ameliorating children's insecurity about community in contexts of political violence is an important goal toward improving adolescents' well-being and adjustment. These results are discussed in terms of their translational research implications, consistent with a developmental psychopathology model for the interface between basic and intervention research.</jats:p

    Nucleon Generalized Parton Distributions and Holographic Models

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    Using ideas from Light Front Holography, we discuss the calculation of the nucleon helicity-independent generalized parton distributions of quarks in the zero skewness case.Comment: Prepared for LIGHTCONE 2011, 23 - 27 May, 2011, Dalla

    Exotic and nonexotic magnetic transitions in the context of the SELEX and GRAAL experiments

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    We calculate magnetic transition moments in the chiral quark-soliton model, with explicit SU(3)-symmetry breaking taken into account. The dynamical model parameters are fixed by experimental data for the magnetic moments of the baryon octet and from the recent measurements of Θ+\Theta^{+} mass. Known magnetic transition moments μΛΣ\mu_{\Lambda\Sigma}, μNΔ\mu_{N\Delta} are reproduced and predictions for other octet-decuplet and octet-antidecuplet transitions are given. In particular μΣΣ\mu_{\Sigma\Sigma^{\ast}} recently constrained by SELEX is shown to be below 0.82μN0.82 \mu_N. The recent GRAAL data on η\eta photoproduction off the nucleon are explained in terms of a new narrow antidecuplet neutron-like resonance.Comment: 14 pages, 9 figures. Final version accepted for publication in Phys.Rev.

    Gamow-Teller transitions and deformation in the proton-neutron random phase approximation

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    We investigate reliability of Gamow-Teller transition strengths computed in the proton-neutron random phase approximation, comparing with exact results from diagonalization in full 0ω0\hbar\omega shell-model spaces. By allowing the Hartree-Fock state to be deformed, we obtain good results for a wide variety of nuclides, even though we do not project onto good angular momentum. We suggest that deformation is as important or more so than pairing for Gamow-Teller transitions.Comment: 8 pages, 5 figures; added references, clarified discussion with regards to stabilit
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