2,302 research outputs found

    TeV SUSY dark matter confronted with the current direct and indirect detection data

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    In the minimal supersymmetric standard model (MSSM) the lightest superparticle (LSP) can be a TeV neutralino (mainly dominated by higgsino or wino) which serves as a dark matter candidate with correct thermal relic density. In this work we confront the 1-2 TeV neutralino dark matter with the latest direct and indirect detections from PandaX and AMS-02/DAMPE. Considering various scenarios with decoupled sfermions, with \textit{A}-mediated annihilation, with squark or stop coannihilation, we find that the parameter space is stringently constrained by the direct detection limits. In the allowed parameter space, the TeV neutralino dark matter annihilation contribution to the anti-proton flux is found to agree with the AMS-02 data while its contribution to eletron/positron flux is too small to cause any visible excess. The current survived parameter space can be mostly covered by the future direct detection experiment LZ7.2T.Comment: 12pages, 5figure

    The origin of p-type conduction in (P, N) co-doped ZnO

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    P mono-doped and (P, N) co-doped ZnO are investigated by the first-principles calculations. It is found that substitutive P defect forms a deep acceptor level at O site (PO) and it behaves as a donor at Zn site (PZn), while interstitial P (Pi) is amphoteric. Under equilibrium conditions, these defects contribute little to the p-type conductivity of ZnO samples since the formation energy of PZn is much lower than that of Pi or PO when EF is below mid-gap (a prerequisite p-type condition). Zinc vacancies (VZn) and PZn-2VZn complex are demonstrated to be shallow acceptors with ionization energies around 100 meV, but they are easily compensated by PZn defect. Fortunately, PZn-4NO complexes may have lower formation energy than that of PZn under Zn rich condition by proper choices of P and N sources. In addition, the neutral PZn-3NO passive defects may form an impurity band right above the valence band maximum of ZnO as in earlier reported (Ga,N) or (Zr,N) doped ZnO. This significantly reduces the acceptor level of PZn-4NO complexes, and helps improving the p-type conductivity in ZnO.Comment: 25 pages, 7 figure

    Unified Universal Quantum Cloning Machine and Fidelities

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    We present a unified universal quantum cloning machine, which combines several different existing universal cloning machines together including the asymmetric case. In this unified framework, the identical pure states are projected equally into each copy initially constituted by input and one half of the maximally entangled states. We show explicitly that the output states of those universal cloning machines are the same. One importance of this unified cloning machine is that the cloning procession is always the symmetric projection which reduces dramatically the difficulties for implementation. Also it is found that this unified cloning machine can be directly modified to the general asymmetric case. Besides the global fidelity and the single-copy fidelity, we also present all possible arbitrary-copy fidelities.Comment: 4 pages, 2 figure
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