13,034 research outputs found

    Reconstruction of the primordial power spectra with Planck and BICEP2

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    By using the cubic spline interpolation method, we reconstruct the shape of the primordial scalar and tensor power spectra from the recently released {\it Planck} temperature and BICEP2 polarization cosmic microwave background data. We find that the vanishing scalar index running (\dd n_s/\dd\ln k) model is strongly disfavored at more than 3Οƒ3\sigma confidence level on the k=0.0002k=0.0002 Mpcβˆ’1^{-1} scale. Furthermore, the power-law parameterization gives a blue-tilt tensor spectrum, no matter using only the first 5 bandpowers nt=1.20βˆ’0.64+0.56(95n_t = 1.20^{+0.56}_{-0.64} (95% {\rm CL}) or the full 9 bandpowers nt=1.24βˆ’0.58+0.51(95n_t = 1.24^{+0.51}_{-0.58} (95% {\rm CL}) of BICEP2 data sets. Unlike the large tensor-to-scalar ratio value (r∼0.20r\sim0.20) under the scale-invariant tensor spectrum assumption, our interpolation approach gives r0.002<0.060(95CL)r_{0.002} < 0.060 (95% {\rm CL}) by using the first 5 bandpowers of BICEP2 data. After comparing the results with/without BICEP2 data, we find that {\it Planck} temperature with small tensor amplitude signals and BICEP2 polarization data with large tensor amplitude signals dominate the tensor spectrum reconstruction on the large and small scales, respectively. Hence, the resulting blue tensor tilt actually reflects the tension between {\it Planck} and BICEP2 data.Comment: complementary results without BICEP2 added, references add, typos corrected, 10 figures, 5 tables, 11 page

    T-Shape Molecular Heat Pump

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    We report on the first molecular device of heat pump modeled by a T-shape Frenkel-Kontorova lattice. The system is a three-terminal device with the important feature that the heat can be pumped from the low-temperature region to the high-temperature region through the third terminal. The pumping action is achieved by applying a stochastic external force that periodically modulates the atomic temperature. The temperature, the frequency and the system size dependence of heat pump are briefly discussed.Comment: 6 figure
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