2,302 research outputs found
TeV SUSY dark matter confronted with the current direct and indirect detection data
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
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
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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