9,881 research outputs found

    Discrete Temporal Models of Social Networks

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    We propose a family of statistical models for social network evolution over time, which represents an extension of Exponential Random Graph Models (ERGMs). Many of the methods for ERGMs are readily adapted for these models, including maximum likelihood estimation algorithms. We discuss models of this type and their properties, and give examples, as well as a demonstration of their use for hypothesis testing and classification. We believe our temporal ERG models represent a useful new framework for modeling time-evolving social networks, and rewiring networks from other domains such as gene regulation circuitry, and communication networks

    The naturalness in the BLMSSM and B-LSSM

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    In order to interpret the Higgs mass and its decays more naturally, we hope to intrude the BLMSSM and B-LSSM. In the both models, the right-handed neutrino superfields are introduced to better explain the neutrino mass problems. In addition, there are other superfields considered to make these models more natural than MSSM. In this paper, the method of χ2\chi^2 analyses will be adopted in the BLMSSM and B-LSSM to calculate the Higgs mass, Higgs decays and muon g−2g-2. With the fine-tuning in the region 0.67%−2.5%0.67\%-2.5\% and 0.67%−5%0.67\%-5\%, we can obtain the reasonable theoretical values that are in accordance with the experimental results respectively in the BLMSSM and B-LSSM. Meanwhile, the best-fitted benchmark points in the BLMSSM and B-LSSM will be acquired at minimal (χminBL)2=2.34736(\chi^{BL}_{min})^2 = 2.34736 and (χminB−L)2=2.47754(\chi^{B-L}_{min})^2 = 2.47754, respectively

    Weak Decays of Stable Open-bottom Tetraquark by SU(3) Symmetry Analysis

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    The exotic state X(5568)X(5568) which was observed by D0 Collaboration is very likely to be a tetraquark state with four different valence quark flavors, though the existence was not confirmed by other collaborations. The possibility of such state still generate lots of interests in theory. In the paper, we will study the properties of the state under the SU(3) flavor symmetry. This four quark state with a heavy bottom quark and three light quarks(anti-quark) can form a 66 or 15‾\overline {15} representation. The weak decays can be dominant and should be discussed carefully while such state is stable against the strong interaction. Therefor we will study the multi-body semileptonic and nonleptonic weak decays systematically. With the help of SU(3) flavor symmetry, we can give the Hamiltonian in the hadronic level, then obtain the parameterized irreducible amplitudes and the relations of different channels. At the end of the article, we collect some Cabibbo allowed two-body and three-body weak decay channels which can be used to reconstruct Xb6X_{b6} states at the branching fraction up to be 10−510^{-5}.Comment: 53 pages, 2 figure
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