22,104 research outputs found

    Next-to-Leading Order Corrections to Single Top Quark Production and Decay at the Tevatron: 1. s-channel Process

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    We present a study of s-channel single top quark production at the upgraded Tevatron ppˉp\bar{p} collider, including the next-to-leading order (NLO) QCD corrections to the production and the decay of the top quark. The "modified" narrow width approximation was adopted to preserve the spin of the top quark in its production and decay. We discuss the effect of the different O(αs)O(\alpha_s) contributions on the inclusive cross section as well as various kinematic distributions after imposing the relevant cuts to select s-channel single top signal events. In particular the O(αs)O(\alpha_s) decay contribution, while small in size, has a significant impact on several distributions. With the help of the best-jet algorithm to reconstruct the top quark we demonstrate that it is possible to study kinematical and spin correlations in s-channel single top events. We furthermore compare top quark spin measurements in two different basis and show how NLO corrections have to be taken into consideration in searches for the Higgs boson through W±HW^{\pm}H associated production at the Tevatron.Comment: 39 pages, 37 figure

    Broadband RCS Reduction of Microstrip Patch Antenna Using Bandstop Frequency Selective Surface

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    In this article, a simple and effective approach is presented to reduce the Radar Cross Section (RCS) of microstrip patch antenna in ultra broad frequency band. This approach substitutes a metallic ground plane of a conventional patch antenna with a hybrid ground consisting of bandstop Frequency Selective Surface (FSS) cells with partial metallic plane. To demonstrate the validity of the proposed approach, the influence of different ground planes on antenna’s performance is investigated. Thus, a patch antenna with miniaturized FSS cells is proposed. The results suggest that this antenna shows 3dB RCS reduction almost in the whole out-of operating band within 1-20GHz for wide incident angles when compared to conventional antenna, while its radiation characteristics are sustained simultaneously. The reasonable agreement between the measured and the simulated results verifies the efficiency of the proposed approach. Moreover, this approach doesn’t alter the lightweight, low-profile, easy conformal and easy manufacturing nature of the original antenna and can be extended to obtain low-RCS antennas with metallic planes in broadband that are quite suitable for the applications which are sensitive to the variation of frequencies

    Single Top Quark Production and Decay at Next-to-leading Order in Hadron Collision

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    We present a calculation of the next-to-leading order QCD corrections, with one-scale phase space slicing method, to single top quark production and decay process ppˉ,pptbˉ+Xbνbˉ+Xp\bar{p},pp\to t\bar{b}+X\to b\ell\nu\bar{b}+X at hadron colliders. Using the helicity amplitude method, the angular correlation of the final state partons and the spin correlation of the top quark are preserved. The effect of the top quark width is also examined.Comment: 47 pages, 9 figure

    Multiband effects on the conductivity for a multiband Hubbard model

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    The newly discovered iron-based superconductors have attracted lots of interests, and the corresponding theoretical studies suggest that the system should have six bands. In this paper, we study the multiband effects on the conductivity based on the exact solutions of one-dimensional two-band Hubbard model. We find that the orbital degree of freedom might enhance the critical value UcU_c of on-site interaction of the transition from a metal to an insulator. This observation is helpful to understand why undoped High-TcT_c superconductors are usually insulators, while recently discovered iron-based superconductors are metal. Our results imply that the orbital degree of freedom in the latter cases might play an essential role.Comment: 4 pages, 5 figure

    Nanofiller-tuned microporous polymer molecular sieves for energy and environmental processes

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    10.1039/c5ta09060aJournal of Materials Chemistry A41270-27

    Anti-Stokes scattering and Stokes scattering of stimulated Brillouin scattering cascade in high-intensity laser-plasmas interaction

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    The anti-Stokes scattering and Stokes scattering in stimulated Brillouin scattering (SBS) cascade have been researched by the Vlasov-Maxwell simulation. In the high-intensity laser-plasmas interaction, the stimulated anti-Stokes Brillouin scattering (SABS) will occur after the second stage SBS rescattering. The mechanism of SABS has been put forward to explain this phenomenon. And the SABS will compete with the SBS rescattering to determine the total SBS reflectivity. Thus, the SBS rescattering including the SABS is an important saturation mechanism of SBS, and should be taken into account in the high-intensity laser-plasmas interaction.Comment: 6 pages, 5 figure
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