10,493 research outputs found

    Optimal Distributed Beamforming for MISO Interference Channels

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    We consider the problem of quantifying the Pareto optimal boundary in the achievable rate region over multiple-input single-output (MISO) interference channels, where the problem boils down to solving a sequence of convex feasibility problems after certain transformations. The feasibility problem is solved by two new distributed optimal beamforming algorithms, where the first one is to parallelize the computation based on the method of alternating projections, and the second one is to localize the computation based on the method of cyclic projections. Convergence proofs are established for both algorithms.Comment: 7 Pages, 6 figures, extended version for the one in Proceeding of Asilomar, CA, 201

    Could Zc(4025)Z_{c}(4025) be a JP=1+J^{P}=1^{+} DDˉD^{*}\bar{D^{*}} molecular state?

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    We investigate whether the newly observed narrow resonance Zc(4025)Z_{c}(4025) can be described as a DDˉD^{*}\bar{D^{*}} molecular state with quantum numbers JP=1+J^{P}=1^{+}. Using QCD sum rules, we consider contributions up to dimension six in the operator product expansion and work at leading order of αs\alpha_{s}. The mass obtained for this state is (4.05\pm 0.28) \mbox{GeV}. It is concluded that DDˉD^{*}\bar{D^{*}} molecular state is a possible candidate for Zc(4025)Z_{c}(4025).Comment: 7 pages, 4 figures.Published in Eur.Phys.J. C73 (2013) 2661. arXiv admin note: text overlap with arXiv:1304.185

    Higher order light-cone distribution amplitudes of the Lambda baryon

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    The improved light-cone distribution amplitudes (LCDAs) of the Λ\Lambda baryon are examined on the basis of the QCD conformal partial wave expansion approach. The calculations are carried out to the next-to-leading order of conformal spin accuracy with consideration of twist 6. The next leading order conformal expansion coefficients are related to the nonperturbative parameters defined by the local three quark operator matrix elements with different Lorentz structures with a covariant derivative. The nonperturbative parameters are determined with the QCD sum rule method. The explicit expressions of the LCDAs are provided as the main results.Comment: 17pages,10figures. arXiv admin note: text overlap with arXiv:1311.596
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