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A model has been proposed to calculate the and dependences in the Y 1?b(Ca)bBa2Cu3O6+x high- cuprate family and applied to , , and cases, for which experimental data exist in the literature. The results obtained imply that the Ca efficiency to provide holes is independent of the basal plane oxygen concentration, which is consistent with a view that electrons from CuO2 layers would go primarily to Ca since it is twice closer than oxygen (in addition, the chain oxygen is screened by a layer made up of Ba and O(4) ions). It is shown that, in fully oxygenized compounds () the average efficiency, , of a chain oxygen to attract an electron from the two nearby layers is reduced by the Ca insertion, though not because the charge transfer mechanism is in itself weakened by Ca, but because a part of electrons that are otherwise available in CuO layers has already been removed by the substitution of Y 3+ with Ca2+. It has been found that the -dependence of the average oxygen doping efficiency can be fairly accurately described by the following relation: . The calculated and dependences are in very good agreement with the available experimental data. 相似文献
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Stephan Narison 《Physics letters. [Part B]》2013,718(4-5):1321-1333
Using recent values of the QCD (non-)perturbative parameters given in Table 1 and an estimate of the N3LO QCD perturbative contributions based on the geometric growth of the PT series, we re-use QCD spectral sum rules (QSSR) known to N2LO PT series and including all dimension-six NP condensate contributions in the full QCD theory, for improving the existing estimates of and from the open charm and beauty systems. We especially study the effects of the subtraction point on “different QSSR data” and use (for the first time) the Renormalization Group Invariant (RGI) scale-independent quark masses in the analysis. The estimates [rigourous model-independent upper bounds within the SVZ framework] reported in Table 8: , and , , which improve previous QSSR estimates, are in perfect agreement (in values and precisions) with some of the experimental data on and on recent lattice simulations within dynamical quarks. These remarkable agreements confirm both the success of the QSSR semi-approximate approach based on the OPE in terms of the quark and gluon condensates and of the Minimal Duality Ansatz (MDA) for parametrizing the hadronic spectral function which we have tested from the complete data of the and ? systems. The values of the running quark masses and from are in good agreement though less accurate than the ones from recent and ? sum rules. 相似文献
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《Journal of Geometry and Physics》2007,57(1):89-100
In this paper we study a generalized Darboux Halphen system given by where , , are real variables, are real constants and We prove that, for any , this system does not admit any non-constant global first integral that can be described by a formal power series. Furthermore, restricting the values of to a full Lebesgue measure set, we prove that this system does not admit any non-constant rational or Darbouxian global first integral. This is a first step toward proving that this system is chaotic. 相似文献
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The pentagram map is now known to be a discrete integrable system. We show that the integrals for the pentagram map are constant along Poncelet families. That is, if and are two polygons in the same Poncelet family, and is a monodromy invariant for the pentagram map, then . Our proof combines complex analysis with an analysis of the geometry of a degenerating sequence of Poncelet polygons. 相似文献
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Jussi Kalkkinen 《Nuclear Physics B》2006,740(3):328-347