9,021 research outputs found

    Dynamics of social contagions with local trend imitation

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    Research on social contagion dynamics has not yet including a theoretical analysis of the ubiquitous local trend imitation (LTI) characteristic. We propose a social contagion model with a tent-like adoption probability distribution to investigate the effect of this LTI characteristic on behavior spreading. We also propose a generalized edge-based compartmental theory to describe the proposed model. Through extensive numerical simulations and theoretical analyses, we find a crossover in the phase transition: when the LTI capacity is strong, the growth of the final behavior adoption size exhibits a second-order phase transition. When the LTI capacity is weak, we see a first-order phase transition. For a given behavioral information transmission probability, there is an optimal LTI capacity that maximizes the final behavior adoption size. Finally we find that the above phenomena are not qualitatively affected by the heterogeneous degree distribution. Our suggested theory agrees with the simulation results.Comment: 14 pages, 5 figure

    Branching Ratios, Forward-backward Asymmetry and Angular Distributions of BK1l+lB\to K_1l^+l^- Decays

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    Using the BK1B\to K_1 form factors evaluated in the perturbative QCD approach, we study semileptonic BK1(1270)l+lB\to K_1(1270)l^+l^- and BK1(1400)l+lB\to K_1(1400)l^+l^- decays, where K1(1270)K_1(1270) and K1(1400)K_1(1400) are mixtures of K1AK_{1A} and K1BK_{1B} which are 3P1^3P_1 and 1P1^1P_1 states, respectively. Using the technique of helicity amplitudes, we express the decay amplitudes in terms of several independent and Lorentz invariant pieces. We study the dilepton invariant mass distributions, branching ratios, polarizations and forward-backward asymmetries of BK1l+l B\to K_1l^+l^- decays. The ambiguity in the sign of the mixing angle will induce much large differences to branching ratios of semileptonic B decays: branching ratios without resonant contributions either have the order of 10610^{-6} or 10810^{-8}. But the polarizations and the forward-backward asymmetries are not sensitive to the mixing angles. We find that the resonant contributions will dramatically change the dilepton invariant mass distributions in the resonant region. We also provide the angular distributions of BK1l+l(Kππ)l+l B\to K_1l^+l^-\to (K\pi\pi)l^+l^- decays.Comment: 14 pages, 6 figures, version appears in PR

    Transition from quintessence to phantom phase in quintom model

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    Assuming the Hubble parameter is a continuous and differentiable function of comoving time, we investigate necessary conditions for quintessence to phantom phase transition in quintom model. For power-law and exponential potential examples, we study the behavior of dynamical dark energy fields and Hubble parameter near the transition time, and show that the phantom-divide-line w=-1 is crossed in these models.Comment: LaTeX, 19 pages, four figures, some minor changes in Introduction, two figures added and the references updated, accepted for publication in Phys. Rev.

    Suppressing disease spreading by using information diffusion on multiplex networks

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    Although there is always an interplay between the dynamics of information diffusion and disease spreading, the empirical research on the systemic coevolution mechanisms connecting these two spreading dynamics is still lacking. Here we investigate the coevolution mechanisms and dynamics between information and disease spreading by utilizing real data and a proposed spreading model on multiplex network. Our empirical analysis finds asymmetrical interactions between the information and disease spreading dynamics. Our results obtained from both the theoretical framework and extensive stochastic numerical simulations suggest that an information outbreak can be triggered in a communication network by its own spreading dynamics or by a disease outbreak on a contact network, but that the disease threshold is not affected by information spreading. Our key finding is that there is an optimal information transmission rate that markedly suppresses the disease spreading. We find that the time evolution of the dynamics in the proposed model qualitatively agrees with the real-world spreading processes at the optimal information transmission rate.Comment: 11 pages, 8 figure

    What can we learn from Ba1(1260)(b1(1235))π(K)B\to a_1(1260)(b_1(1235))\pi(K) decays?

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    We investigate the Ba1(1260)(b1(1235))π(K)B\to a_1(1260)(b_1(1235))\pi(K) decays under the factorization scheme and find many discrepancies between theoretical predictions and the experimental data. In the tree dominated processes, large contributions from color-suppressed tree diagrams are required in order to accommodate with the large decay rates of Ba10πB^-\to a_1^0\pi^- and Ba1π0B^-\to a_1^-\pi^0. For Bˉ0(a1+,b1+)K\bar B^0\to (a_1^+, b_1^+)K^- decays which are both induced by bsb\to s transition, theoretical predictions on their decay rates are larger than the data by a factor of 2.8 and 5.5, respectively. Large electro-weak penguins or some new mechanism are expected to explain the branching ratios of Bb10KB^-\to b_1^0K^- and Ba1Kˉ0B^-\to a_1^-\bar K^0. The soft-collinear-effective-theory has the potential to explain large decay rates of Ba10πB^-\to a_1^0\pi^- and Ba1π0B^-\to a_1^-\pi^0 via a large hard-scattering form factor ζJBa1\zeta_J^{B\to a_1}. We will also show that, with proper charming penguins, predictions on the branching ratios of Bˉ0(a1+,b1+)K\bar B^0\to (a_1^+, b_1^+)K^- can also be consistent with the data.Comment: 16 pages, no figur

    Charmless Two-body B(Bs)VPB(B_s)\to VP decays In Soft-Collinear-Effective-Theory

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    We provide the analysis of charmless two-body BVPB\to VP decays under the framework of the soft-collinear-effective-theory (SCET), where V(P)V(P) denotes a light vector (pseudoscalar) meson. Besides the leading power contributions, some power corrections (chiraly enhanced penguins) are also taken into account. Using the current available BPPB\to PP and BVPB\to VP experimental data on branching fractions and CP asymmetry variables, we find two kinds of solutions in χ2\chi^2 fit for the 16 non-perturbative inputs which are essential in the 87 BPPB\to PP and BVPB\to VP decay channels. Chiraly enhanced penguins can change several charming penguins sizably, since they share the same topology. However, most of the other non-perturbative inputs and predictions on branching ratios and CP asymmetries are not changed too much. With the two sets of inputs, we predict the branching fractions and CP asymmetries of other modes especially BsVPB_s\to VP decays. The agreements and differences with results in QCD factorization and perturbative QCD approach are analyzed. We also study the time-dependent CP asymmetries in channels with CP eigenstates in the final states and some other channels such as Bˉ0/B0π±ρ\bar B^0/B^0\to\pi^\pm\rho^\mp and Bˉs0/Bs0K±K\bar B_s^0/B_s^0\to K^\pm K^{*\mp}. In the perturbative QCD approach, the (SP)(S+P)(S-P)(S+P) penguins in annihilation diagrams play an important role. Although they have the same topology with charming penguins in SCET, there are many differences between the two objects in weak phases, magnitudes, strong phases and factorization properties.Comment: 34 pages, revtex, 2 figures, published at PR

    Interacting Agegraphic Dark Energy

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    A new dark energy model, named "agegraphic dark energy", has been proposed recently, based on the so-called K\'{a}rolyh\'{a}zy uncertainty relation, which arises from quantum mechanics together with general relativity. In this note, we extend the original agegraphic dark energy model by including the interaction between agegraphic dark energy and pressureless (dark) matter. In the interacting agegraphic dark energy model, there are many interesting features different from the original agegraphic dark energy model and holographic dark energy model. The similarity and difference between agegraphic dark energy and holographic dark energy are also discussed.Comment: 10 pages, 5 figures, revtex4; v2: references added; v3: accepted by Eur. Phys. J. C; v4: published versio
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