64 research outputs found

    Exact ground-state correlation functions of the one-dimensional strongly correlated electron models with the resonating-valence-bond ground state

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    We investigate the one-dimensional strongly correlated electron models which have the resonating-valence-bond state as the exact ground state. The correlation functions are evaluated exactly using the transfer matrix method for the geometric representations of the valence-bond states. In this method, we only treat matrices with small dimensions. This enables us to give analytical results. It is shown that the correlation functions decay exponentially with distance. The result suggests that there is a finite excitation gap, and that the ground state is insulating. Since the corresponding non-interacting systems may be insulating or metallic, we can say that the gap originates from strong correlation. The persistent currents of the present models are also investigated and found to be exactly vanishing.Comment: 59 pages, REVTeX 3.0, Figures are available on reques

    How do trypanosomes change gene expression in response to the environment?

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    The so-called tobacco wireworm in Virginia /

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    no.78 (1914
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