8,578 research outputs found

    Probing neutral top-pion via a flavor-changing process γγ→tcˉΠt0\gamma\gamma\to t\bar{c}\Pi_{t}^{0}

    Full text link
    In the framework of topcolor-assisted-technicolor model(TC2), we study a flavor-changing neutral top-pion production process γγ→tcˉΠt0\gamma\gamma\to t\bar{c}\Pi_{t}^{0}. The study shows that there exists a resonance effect which can enhance the cross section up to a few fb even tens fb. For a yearly luminosity 100 fb−1fb^{-1} at future linear colliders, there might be hundreds even thousands events to be produced. On the other hand, the background of such flavor-changing process is very clean due to the GIM mechanism in SM . With such sufficient events and clean background, neutral toppion could be detected at future linear colliders with high center of energy and luminosity. Our study provides a possible way to test TC2 model.Comment: 10 pages, 4 figures,has been accepted by Phys.Rev.

    Topological quantum phase transition in an extended Kitaev spin model

    Full text link
    We study the quantum phase transition between Abelian and non-Abelian phases in an extended Kitaev spin model on the honeycomb lattice, where the periodic boundary condition is applied by placing the lattice on a torus. Our analytical results show that this spin model exhibits a continuous quantum phase transition. Also, we reveal the relationship between bipartite entanglement and the ground-state energy. Our approach directly shows that both the entanglement and the ground-state energy can be used to characterize the topological quantum phase transition in the extended Kitaev spin model.Comment: 9 Pages, 4 figure

    High-resolution (375 m) cloud microstructure as seen from the NPP/VIIRS satellite imager

    Get PDF
    VIIRS (Visible Infrared Imaging Radiometer Suite), onboard the Suomi NPP (National Polar-orbiting Partnership) satellite, has an improved resolution of 750 m with respect to the 1000 m of the Moderate Resolution Imaging Spectroradiometer for the channels that allow retrieving cloud microphysical parameters such as cloud drop effective radius (<i>r</i><sub>e</sub>). VIIRS also has an imager with five channels of double resolution of 375 m, which was not designed for retrieving cloud products. A methodology for a high-resolution retrieval of <i>r</i><sub>e</sub> and microphysical presentation of the cloud field based on the VIIRS imager was developed and evaluated with respect to MODIS in this study. The tripled microphysical resolution with respect to MODIS allows obtaining new insights for cloud–aerosol interactions, especially at the smallest cloud scales, because the VIIRS imager can resolve the small convective elements that are sub-pixel for MODIS cloud products. Examples are given for new insights into ship tracks in marine stratocumulus, pollution tracks from point and diffused sources in stratocumulus and cumulus clouds over land, deep tropical convection in pristine air mass over ocean and land, tropical clouds that develop in smoke from forest fires and in heavy pollution haze over densely populated regions in southeastern Asia, and for pyro-cumulonimbus clouds. <br> It is found that the VIIRS imager provides more robust physical interpretation and refined information for cloud and aerosol microphysics as compared to MODIS, especially in the initial stage of cloud formation. VIIRS is found to identify significantly more fully cloudy pixels when small boundary layer convective elements are present. This, in turn, allows for a better quantification of cloud–aerosol interactions and impacts on precipitation-forming processes

    A Feasibility Study of SSVEP-Based Passive Training on an Ankle Rehabilitation Robot

    Get PDF
    Objective: This study aims to establish a steady-state visual evoked potential- (SSVEP-) based passive training protocol on an ankle rehabilitation robot and validate its feasibility. Method: This paper combines SSVEP signals and the virtual reality circumstance through constructing information transmission loops between brains and ankle robots. The robot can judge motion intentions of subjects and trigger the training when subjects pay their attention on one of the four flickering circles. The virtual reality training circumstance provides real-time visual feedback of ankle rotation. Result: All five subjects succeeded in conducting ankle training based on the SSVEP-triggered training strategy following their motion intentions. The lowest success rate is 80%, and the highest one is 100%. The lowest information transfer rate (ITR) is 11.5 bits/min when the biggest one of the robots for this proposed training is set as 24 bits/min. Conclusion: The proposed training strategy is feasible and promising to be combined with a robot for ankle rehabilitation. Future work will focus on adopting more advanced data process techniques to improve the reliability of intention detection and investigating how patients respond to such a training strategy

    Poling effect on distribution of quenched random fields in a uniaxial relaxor ferroelectric

    Full text link
    The frequency dependence of the dielectric permitivity's maximum has been studied for poled and unpoled doped relaxor strontium barium niobate Sr0.61Ba0.39Nb2O6:Cr3+Sr_{0.61}Ba_{0.39}Nb_{2}O_{6}:Cr^{3+} (SBN-61:Cr). In both cases the maximum found is broad and the frequency dispersion is strong. The present view of random fields compensation in the unpoled sample is not suitable for explaining this experimental result. We propose a new mechanism where the dispersion of quenched random electric fields, affecting the nanodomains, is minimized after poling. We test our proposal by numerical simulations on a random field Ising model. Results obtained are in agreement with the polarization's measurements presented by Granzow et al. [Phys. Rev. Lett {\bf 92}, 065701 (2004)].Comment: 7 pages, 4 figure

    Production of the neutral top-pion πt0\pi_{t}^{0} in association with a high-pTp_{T} jet at the LHCLHC

    Full text link
    In the framework of the topcolor-assisted technicolor (TC2)(TC2) model, we study production of the neutral top-pion πt0\pi_{t}^{0} in association with a high-pTp_{T} jet at the LHCLHC, which proceeds via the partonic processes gg⟶πt0ggg\longrightarrow \pi_{t}^{0}g, gq⟶πt0qgq\longrightarrow \pi_{t}^{0}q, qqˉ⟶πt0gq\bar{q}\longrightarrow \pi_{t}^{0}g, gb(bˉ)⟶πt0b(bˉ)gb(\bar{b})\longrightarrow \pi_{t}^{0}b(\bar{b}), and bbˉ⟶πt0gb\bar{b}\longrightarrow \pi_{t}^{0}g. We find that it is very challenging to detect the neutral top-pion πt0\pi_{t}^{0} via the process pp⟶πt0+jet+X→ttˉ+jet+Xpp\longrightarrow \pi_{t}^{0}+jet+X\to t\bar{t}+jet+X, while the possible signatures of πt0\pi_{t}^{0} might be detected via the process pp⟶πt0+jet+X→(tˉc+tcˉ)+jet+Xpp\longrightarrow \pi_{t}^{0}+jet+X\to(\bar{t}c+t\bar{c})+jet+X at the LHCLHC.Comment: 13 pages, 4 figures; typos correcte
    • …
    corecore