27,394 research outputs found

    Self-interacting dark matter and Higgs bosons in the SU(3)_C x SU(3)_L x U(1)_N model with right-handed neutrinos

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    We investigate the possibility that dark matter could be made from CP-even and CP- odd Higgs bosons in the SU(3)_C X SU(3)_L X U(1)_N (3-3-1) model with right-handed neutrinos. This self-interacting dark matters are stable without imposing of new symmetry and should be weak-interacting.Comment: 7 pages, Latex, To appear in Europhys. Let

    X-ray Emission of Baryonic Gas in the Universe: Luminosity-Temperature Relationship and Soft-Band Background

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    We study the X-ray emission of baryon fluid in the universe using the WIGEON cosmological hydrodynamic simulations. It has been revealed that cosmic baryon fluid in the nonlinear regime behaves like Burgers turbulence, i.e. the fluid field consists of shocks. Like turbulence in incompressible fluid, the Burgers turbulence plays an important role in converting the kinetic energy of the fluid to thermal energy and heats the gas. We show that the simulation sample of the Λ\LambdaCDM model without adding extra heating sources can fit well the observed distributions of X-ray luminosity versus temperature (LxL_{\rm x} vs. TT) of galaxy groups and is also consistent with the distributions of X-ray luminosity versus velocity dispersion (LxL_{\rm x} vs. σ\sigma). Because the baryonic gas is multiphase, the LxTL_{\rm x}-T and LxσL_{\rm x}-\sigma distributions are significantly scattered. If we describe the relationships by power laws LxTαLTL_{\rm x}\propto T^{\alpha_{LT}} and LxσαLVL_{\rm x}\propto \sigma^{\alpha_{LV}}, we find αLT>2.5\alpha_{LT}>2.5 and αLV>2.1\alpha_{LV}>2.1. The X-ray background in the soft 0.520.5-2 keV band emitted by the baryonic gas in the temperature range 105<T<10710^5<T<10^7 K has also been calculated. We show that of the total background, (1) no more than 2% comes from the region with temperature less than 106.510^{6.5} K, and (2) no more than 7% is from the region of dark matter with mass density ρdm<50ρˉdm\rho_{\rm dm}<50 \bar{\rho}_{\rm dm}. The region of ρdm>50ρˉdm\rho_{\rm dm}>50\bar{\rho}_{\rm dm} is generally clustered and discretely distributed. Therefore, almost all of the soft X-ray background comes from clustered sources, and the contribution from truly diffuse gas is probably negligible. This point agrees with current X-ray observations.Comment: 32 pages including 14 figures and 2 tables. Final version for publication in Ap

    A quantitative evaluation of metallic conduction in conjugated polymers

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    As the periodicity in crystalline materials creates the optimal condition for electronic delocalization, one might expect that in partially crystalline conjugated polymers delocalization is impeded by intergrain transport. However, for the best conducting polymers this presumption fails. Delocalization is obstructed by interchain rather than intergrain charge transfer and we propose a model of weakly coupled disordered chains to describe the physics near the metal-insulator transition. Our quantitative calculations match the outcome of recent broad-band optical experiments and provide a consistent explanation of metallic conduction in polymers.Comment: 4 pages incl. 3 figure
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