57,925 research outputs found

    Formation of \eta'(958)-mesic nuclei and axial U_A(1) anomaly at finite density

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    We discuss the possibility to produce the bound states of the η(958)\eta'(958) meson in nuclei theoretically. We calculate the formation cross sections of the η\eta' bound states with the Green function method for (γ\gamma,p) reaction and discuss the experimental feasibility at photon facilities like SPring-8. We conclude that we can expect to observe resonance peaks in (γ\gamma,p) spectra for the formation of η\eta' bound states and we can deduce new information on η\eta' properties at finite density. These observations are believed to be essential to know the possible mass shift of η\eta' and deduce new information of the effective restoration of the chiral UA(1)U_A(1) anomaly in the nuclear medium.Comment: 4 pages, 3 figure

    Differential symmetry breaking operators I : General theory and F-method

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    Determination of polarized parton distribution functions

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    We study parametrization of polarized parton distribution functions in the \alpha_s leading order (LO) and in the next-to-leading order (NLO). From \chi^2 fitting to the experimental data on A_1, optimum polarized distribution functions are determined. The quark spin content \Delta\Sigma is very sensitive to the small-x behavior of antiquark distributions which suggests that small-x data are needed for precise determination of \Delta\Sigma. We propose three sets of distributions and also provide FORTRAN library for our distributions.Comment: 1+5 pages, LATEX, aipproc.sty, 4 eps figures. Talk given at the 14th International Spin Physics Symposium, Osaka, Japan, October 16-21, 200

    Quantum network coding for quantum repeaters

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    This paper considers quantum network coding, which is a recent technique that enables quantum information to be sent on complex networks at higher rates than by using straightforward routing strategies. Kobayashi et al. have recently showed the potential of this technique by demonstrating how any classical network coding protocol gives rise to a quantum network coding protocol. They nevertheless primarily focused on an abstract model, in which quantum resource such as quantum registers can be freely introduced at each node. In this work, we present a protocol for quantum network coding under weaker (and more practical) assumptions: our new protocol works even for quantum networks where adjacent nodes initially share one EPR-pair but cannot add any quantum registers or send any quantum information. A typically example of networks satisfying this assumption is {\emph{quantum repeater networks}}, which are promising candidates for the implementation of large scale quantum networks. Our results thus show, for the first time, that quantum network coding techniques can increase the transmission rate in such quantum networks as well.Comment: 9 pages, 11figure

    A tight analysis of Kierstead-Trotter algorithm for online unit interval coloring

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    Kierstead and Trotter (Congressus Numerantium 33, 1981) proved that their algorithm is an optimal online algorithm for the online interval coloring problem. In this paper, for online unit interval coloring, we show that the number of colors used by the Kierstead-Trotter algorithm is at most 3ω(G)33 \omega(G) - 3, where ω(G)\omega(G) is the size of the maximum clique in a given graph GG, and it is the best possible.Comment: 4 page

    The Nature of Support from Adult Sansei (Third Generation) Children to Older Nisei (Second Generation) Parents in Japanese Canadian Families

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    Given the growing ethnocultural diversity of Canada's aging population and the increased research focus on the role of the family in the social support of older persons, it is important to explore the ways in which adult ethnic minority children provide assistance to older parents within the context of the family. The current study contributes to research on intergenerational support systems in later life in Japanese Canadian families by examining the factors, particularly the cultural value of oya koh koh (filial obligation), affecting the nature of support from adult children to older parents. Using data gathered from interviews with 100 older nisei (second generation) parents and 100 adult sansei (third generation) children in British Columbia, the study focuses on the frequency, quality and provision of three types of support: emotional, service, and financial. Results of logistic regression analyses indicate that oya koh koh has a significant effect on children's provision of emotional support, but no effect on financial or service support. Parent's health and socioeconomic status are found to have significant effects on children's provision of financial and service support. Child's availability is also a major determinant of financial support. Further, ordinary least squares (OLS) regression analyses results suggest that oya koh koh has a significant effect on the quality of emotional support provided by children to their parents. Findings are discussed in terms of the North American Asian "ideal" family myth and directions for future research.family support; filial obligation, intergenerational relations; Japanese Canadian; model minority myth

    Global analysis by hidden symmetry

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    Hidden symmetry of a G'-space X is defined by an extension of the G'-action on X to that of a group G containing G' as a subgroup. In this setting, we study the relationship between the three objects: (A) global analysis on X by using representations of G (hidden symmetry); (B) global analysis on X by using representations of G'; (C) branching laws of representations of G when restricted to the subgroup G'. We explain a trick which transfers results for finite-dimensional representations in the compact setting to those for infinite-dimensional representations in the noncompact setting when XCX_C is GCG_C-spherical. Applications to branching problems of unitary representations, and to spectral analysis on pseudo-Riemannian locally symmetric spaces are also discussed.Comment: Special volume in honor of Roger Howe on the occasion of his 70th birthda

    Quantum States from Tangent Vectors

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    We argue that tangent vectors to classical phase space give rise to quantum states of the corresponding quantum mechanics. This is established for the case of complex, finite-dimensional, compact, classical phase spaces C, by explicitly constructing Hilbert-space vector bundles over C. We find that these vector bundles split as the direct sum of two holomorphic vector bundles: the holomorphic tangent bundle T(C), plus a complex line bundle N(C). Quantum states (except the vacuum) appear as tangent vectors to C. The vacuum state appears as the fibrewise generator of N(C). Holomorphic line bundles N(C) are classified by the elements of Pic(C), the Picard group of C. In this way Pic(C) appears as the parameter space for nonequivalent vacua. Our analysis is modelled on, but not limited to, the case when C is complex projective space.Comment: Refs. update