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1.
In this paper, we make a deep analysis for the five typical interacting holographic dark energy models with the interaction terms \(Q=3\beta H_{0}\rho _\mathrm{{de}}\), \(Q=3\beta H_{0}\rho _\mathrm{{c}}\), \(Q=3\beta H_{0}(\rho _\mathrm{{de}}+\rho _\mathrm{c})\), \(Q=3\beta H_{0}\sqrt{\rho _\mathrm{{de}}\rho _\mathrm{c}}\), and \(Q=3\beta H_{0}\frac{\rho _\mathrm{{de}}\rho _{c}}{\rho _\mathrm{{de}}+\rho _\mathrm{c}}\), respectively. We obtain observational constraints on these models by using the type Ia supernova data (the Joint Light-Curve Analysis sample), the cosmic microwave background data (Planck 2015 distance priors), the baryon acoustic oscillations data, and the direct measurement of the Hubble constant. We find that the values of \(\chi _\mathrm{min}^2\) for all the five models are almost equal (around 699), indicating that the current observational data equally favor these IHDE models. In addition, a comparison with the cases of an interaction term involving the Hubble parameter H is also made.  相似文献   

2.
We compute the mid-rapidity densities of pions, kaons, baryons and antibaryons in Au-Au collisions at GeV in the dual parton model supplemented with final state interaction (comovers interaction). The ratios ( ) increase between peripheral ( ) and central ( collisions by a factor 2.4 (2.0) for the , 4.8 (4.1) for the and 16.5 (13.5) for the . The ratio increases by a factor 1.3 in the same centrality range. A comparison with the available data is presented.Received: 28 April 2003, Published online: 11 July 2003  相似文献   

3.
A very economic model of generating small neutrino masses is the Zee model. This model has been studied extensively in the literature with most of the studies concentrated on the simplest version of the model, where all diagonal entries in the mass matrix are zero. SNO, and KamLAND data disfavor this simple version, but only when one also combines information from atmospheric and K2K data can one rule out this model with a high confidence level. We show that the simplest version of the Zee model is ruled out at level. The original Zee model, however, contains more than enough freedom to satisfy constraints from the data. We propose a new form of mass matrix by a naturalness consideration. This new form of the mass matrix is consistent with all experimental data. It predicts that , and increases and decreases with |Ve3|. For and to be in their allowed regions, |Ve3| is sizeable but can be set below the 90% C.L. upper bound.Received: 8 December 2003, Published online: 19 March 2004  相似文献   

4.
Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries from a longitudinally polarized target. The single spin asymmetries A UT from the transversely polarized proton target are found to be about for positive and neutral pions both at HERMES and COMPASS. For a longitudinally polarized target we obtain for COMPASS and .Received: 18 September 2003, Published online: 26 November 2003  相似文献   

5.
OL-1-type material (birnessite) is synthesized by an oxidoreduction process. Different physicochemical techniques were used to characterize the obtained material. AC impedance spectroscopy results show processes associated to the electrical conduction in bulk and grain boundary at high frequency, and an ionic conduction at low frequency. Here σ′(ω) shows a universal Jonscher’s law behavior associated to the electron hopping and charge polarization, and the value of 8.39?×?10?6 Ω?1?cm?1 found in the high frequency region at room temperature suggests its semiconductor nature. The combined results of AOS, TGA, and AA suggest the following chemical formula $ {\text{N}}{{\text{a}}^{ + }}_{{0.28}}\left( {{\text{M}}{{\text{g}}^{{2 + }}}_{{0.16}}{\text{M}}{{\text{n}}^{{4 + }}}_{{0.46}}{\text{M}}{{\text{n}}^{{3 + }}}_{{0.54}}} \right){{\text{O}}_{{2.03}}} \cdot 0.6{{\text{H}}_2}{\text{O}} $ . Finally, the XRD pattern is characteristic of OL-1-type materials, the BET area was 56,25 m2 g?1, and the behavior of N2 isotherms suggests the presence of microporous and mesoporous structures. With the purpose of obtaining a better understanding of the ionic conductivity in these types of materials, magnesium exchange material was prepared and electrical properties at room temperature were analyzed. These results indicate that there is interplay among the structural, morphological, and textural properties with the electrical performance of these materials.  相似文献   

6.
We herein investigate theoretically both 2D and 3D Hybrid Organic/inorganic perovskite crystal structures based on density functional theory (DFT) calculations and symmetry analyses. Our findings reveal the universal features of the electronic band structure for the class of lead-halide hybrids (R-NH \(_{3})_{n}\hbox {PbX}_{m}\) , where \((\mathrm{{n}}, \mathrm{{m}})=(2,4)\) and (1,3) respectively for 2D and 3D structures. Among those, the large spin-orbit coupling acting on the conduction band is shown to play a major role on the band gap of these materials. Moreover, this approach can easily be generalized to related layered and 3D hybrids, thus providing a clear-sighted inside in their electronic and optical properties.  相似文献   

7.
Equilibrium between the ion exchange membrane and solutions of anions at various valences has been the subject of this investigation. Competitive ion exchange reactions were studied on a strong base anion exchange membrane AMX manufactured by Tokuyama, commercialized by Eurodia, involving Cl?, $ {\text NO}_3^{ - } $ and $ {\text SO}_4^{{2 - }} $ ions. Solution concentrations studied were 0.05 and 0.1 M for all the systems reported. Experiments were performed with sodium as the counter ion, and the temperature was kept constant (T?=?298 K). Ionic exchange isotherms for the binary systems— $ {{\text Cl}^{ - }}/{\text NO}_3^{ - } $ , $ {{\text Cl}^{ - }}/{\text SO}_4^{{2 - }} $ , and $ {\text NO}_3^{ - }/{\text SO}_4^{{2 - }} $ —were established. The obtained results show that the sulfate was the most strongly sorbed, and the selectivity order is $ {\text SO}_4^{{2 - }} > {\text NO}_3^{ - } > {{\text Cl}^{ - }} $ at 0.05 M and $ {\text NO}_3^{ - } > {\text SO}_4^{{2 - }} > {{\text Cl}^{ - }} $ at 0.1 M under the experimental conditions. Selectivity coefficients $ K_{{{{{\text Cl} }^{ - }}}}^{{{\text NO}_3^{ - }}} $ , $ K_{{2{{{\text Cl} }^{ - }}}}^{{{\text SO}_4^{{2 - }}}} $ , and $ K_{{2{\text NO}_3^{ - }}}^{{{\text SO}_4^{{2 - }}}} $ for the three binary systems were determined. All the results given by this membrane were compared with those obtained, in the same conditions, with the RPA membrane (produced by RHONE POULENC). Ternary equilibrium data were taken for $ {{\text Cl}^{ - }}/{\text NO}_3^{ - }/{\text SO}_4^{{2 - }} $ . The prediction of the ternary system based only on the binary data was consistent with the experimental data obtained for this system. The good agreement between the experimental and the predicted data showed that the proposed framework can be considered as an effective method to predict many ternary systems from binary systems.  相似文献   

8.
The activities of bacterial consortia enable organisms to maximize their metabolic capabilities. This article assesses the synergetic relationship between iron reducing bacteria (IRB), Shewanella putrefaciens and sulphate reducing bacteria (SRB) Desulfovibrio alaskensis. Thus, the aim of this study was first to form a biogenic hydroxy-sulpahte green rust GR2( $ {\text{SO}}_{{\text{4}}} ^{{2 - }} The activities of bacterial consortia enable organisms to maximize their metabolic capabilities. This article assesses the synergetic relationship between iron reducing bacteria (IRB), Shewanella putrefaciens and sulphate reducing bacteria (SRB) Desulfovibrio alaskensis. Thus, the aim of this study was first to form a biogenic hydroxy-sulpahte green rust GR2() through the bioreduction of lepidocrocite by S. putrefaciens and secondly to investigate if sulfate anions intercalated in the biogenic GR2() could serve as final electron acceptor for a sulfate reducing bacterium, D. alaskensis. The results indicate that the IRB lead to the formation of GR2() and this mineral serve as an electron acceptor for SRB. GR2() precipitation and its transformation was demonstrated by using X-ray diffraction (DRX), M?ssbauer spectroscopy (TMS) and transmission electron spectroscopy (TEM). These observations point out the possible acceleration of steel corrosion in marine environment in presence of IRB/SRB consortia.  相似文献   

9.
Under the assumption that at high energies total absorption prevails so that the imaginary part of the scattering amplitude dominates, we present a sum rule for all hadronic elastic differential cross-sections. We find that the dimensionless quantity , at asymptotic energies. A comparison with experimental data from ISR and Tevatron confirms a trend towards its saturation and some estimates are presented for LHC. Its universality and further consequences for the nature of absorption in QCD based models for elastic and total cross-sections are explored.Received: 15 August 2004, Revised: 27 April 2005, Published online: 8 July 2005  相似文献   

10.
We describe a model for the scalar sector where all interactions occur either at an ultra-high scale, ΛU~1016-1019 GeV, or at an intermediate scale, ΛI = 109-1011 GeV. The interaction of physics on these two scales results in an SU(2) Higgs condensate at the electroweak (EW) scale, ΛEW, through a seesaw-like Higgs mechanism, , while the breaking of the SM SU(2) x U(1) gauge symmetry occurs at the intermediate scale ΛI . The EW scale is, therefore, not fundamental but is naturally generated in terms of ultra-high energy phenomena and so the hierarchy problem is alleviated. We show that the class of such "seesaw Higgs" models predict the existence of sub-eV neutrino masses which are generated through a "two-step" seesaw mechanism in terms of the same two ultra-high scales: . The neutrinos can be either Dirac or Majorana, depending on the structure of the scalar potential. We also show that our seesaw Higgs model can be naturally embedded in theories with tiny extra dimensions of size fm, where the seesaw induced EW scale arises from a violation of a symmetry at a distant brane; in particular, in the scenario presented there are seven tiny extra dimensions. Received: 19 August 2004, Revised: 27 July 2005, Published online: 14 October 2005  相似文献   

11.
A novel high precision method measures the b-quark forward-backward asymmetry at the Z pole on a sample of 3,560,890 hadronic events collected with the DELPHI detector in 1992 to 2000. An enhanced impact parameter tag provides a high purity b sample. For event hemispheres with a reconstructed secondary vertex the charge of the corresponding quark or anti-quark is determined using a neural network which combines in an optimal way the full available charge information from the vertex charge, the jet charge and from identified leptons and hadrons. The probability of correctly identifying b-quarks and anti-quarks is measured on the data themselves comparing the rates of double hemisphere tagged like-sign and unlike-sign events. The b-quark forward-backward asymmetry is determined from the differential asymmetry, taking small corrections due to hemisphere correlations and background contributions into account. The results for different centre-of-mass energies are: .Combining these results yields the b-quark pole asymmetry Received: 22 July 2004, Revised: 9 December 2004, Published online: 4 February 2005  相似文献   

12.
Nano-structured $\mathrm{TiO }_{2}$ planar waveguides were prepared by sol–gel route: titanium tetraisopropoxide was dissolved in isopropanol, and then hydrolyzed by adding a water/isopropanol mixture with a controlled hydrolysis ratio. The resulting sol was deposited by “dip-coating” on a glass substrate with a controlled withdrawal speed. The obtained films were annealed for 2 h at 350 and $500\,^{\circ }\mathrm C $ , respectively. The structural and morphological properties of the synthesized films were analyzed by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. Optical properties such as refractive index, thickness, number of propagating modes, and attenuation coefficient were measured at 632.8 nm by m-lines spectroscopy as a function of the elaboration parameters. The films exhibit diffraction pattern consistent with an anatase phase and the $\mathrm{TiO }_{2}$ planar waveguides are multimodes and demonstrate propagation losses as low as 0.3 dB/cm.  相似文献   

13.
Finite temperature Euclidean SU(2) lattice gauge fields close to the deconfinement phase transition are subjected to cooling. We find relatively stable or absolutely stable configurations with an action below the one-instanton action both in the deconfinement and the confinement phases. In this paper we attempt to interpret these lowest action configurations. Their action is purely magnetic and amounts to , where Nt (Ns) is the timelike (spacelike) lattice size, while the topological charge vanishes. In the confined phase part of the corresponding lattice configurations turns out to be absolutely stable with respect to the cooling process in which case Abelian projection reveals a homogeneous, purely Abelian magnetic field closed over the boundary in one of the spatial directions. Referring to the dyonic structure established for the confinement phase near Tc and based on the observation made for this phase that such events below the instanton action Sinst emerge from dyon-antidyon annihilation, the question of the stability (metastability) is discussed for both phases. The hypothetically different dyonic structure of the deconfinement phase, inaccessible by cooling, could explain the metastability.Received: 14 October 2003, Revised: 27 January 2004, Published online: 8 April 2004  相似文献   

14.
Mehner  H.  Menzel  M.  Nofz  M. 《Hyperfine Interactions》2004,158(1-4):347-351
A Perturbed Angular Correlation (PAC) study was performed on the system that presents a rich variety of structural and magnetic phase transitions as a function of the oxygen content (δ) or as a function of temperature (T). The PAC signal at room temperature allowed the determination of the Electrical Field Gradient (EFG) parameters and to correlate them with the lattice average symmetry namely the orthorhombic (O′ or O*) Pbnm and rhombohedral (R) phases measured by X-ray diffraction.  相似文献   

15.
We demonstrate a Doppler cooling and detection scheme for ions with low-lying D levels which almost entirely suppresses scattered laser light background, while retaining a high fluorescence signal and efficient cooling. We cool a single ion with a laser on the $^{2}\mathrm{S}_{\mbox{\tiny$1/2$}}\leftrightarrow {^{2}\mathrm{P}}_{\mbox{\tiny$1/2$}}$ transition as usual, but repump via the $^{2}\mathrm{P}_{\mbox{\tiny$3/2$}}$ level. By filtering out light on the cooling transition and detecting only the fluorescence from the $^{2}\mathrm{P}_{\mbox{\tiny$3/2$}}\rightarrow {^{2}\mathrm{S}}_{\mbox{\tiny$1/2$}}$ decays, we suppress the scattered laser light background count rate to 1 s?1 while maintaining a signal of 29000 s?1 with moderate saturation of the cooling transition. This scheme will be particularly useful for experiments where ions are trapped in close proximity to surfaces, such as the trap electrodes in microfabricated ion traps, which leads to high background scatter from the cooling beam.  相似文献   

16.
Moments of the hadronic invariant mass and of the lepton energy spectra in semileptonic B decays have been determined with the data recorded by the DELPHI detector at LEP. From measurements of the inclusive b-hadron semileptonic decays, and imposing constraints from other measurements on b- and c-quark masses, the first three moments of the lepton energy distribution and of the hadronic mass distribution, have been used to determine parameters which enter into the extraction of |Vcb| from the measurement of the inclusive b-hadron semileptonic decay width. The values obtained in the kinetic scheme are: and include corrections at order 1/mb3. Using these results, and present measurements of the inclusive semileptonic decay partial width of b-hadrons at LEP, an accurate determination of |Vcb| is obtained: Received: 26 April 2005, Revised: 16 September 2005, Published online: 16 November 2005  相似文献   

17.
The Schrödinger  equation for a particle of rest mass $m$ and electrical charge $ne$ interacting with a four-vector potential $A_i$ can be derived as the non-relativistic limit of the Klein–Gordon  equation $\left( \Box '+m^2\right) \varPsi =0$ for the wave function $\varPsi $ , where $\Box '=\eta ^{jk}\partial '_j\partial '_k$ and $\partial '_j=\partial _j -\mathrm {i}n e A_j$ , or equivalently from the one-dimensional  action $S_1=-\int m ds +\int neA_i dx^i$ for the corresponding point particle in the semi-classical approximation $\varPsi \sim \exp {(\mathrm {i}S_1)}$ , both methods yielding the equation $\mathrm {i}\partial _0\varPsi \approx \left( \frac{1}{2m}\eta ^{\alpha \beta }\partial '_{\alpha }\partial '_{\beta } + m + n e\phi \right) \varPsi $ in Minkowski  space–time  , where $\alpha ,\beta =1,2,3$ and $\phi =-A_0$ . We show that these two methods generally yield equations  that differ in a curved background  space–time   $g_{ij}$ , although they coincide when $g_{0\alpha }=0$ if $m$ is replaced by the effective mass $\mathcal{M}\equiv \sqrt{m^2-\xi R}$ in both the Klein–Gordon  action $S$ and $S_1$ , allowing for non-minimal coupling to the gravitational  field, where $R$ is the Ricci scalar and $\xi $ is a constant. In this case $\mathrm {i}\partial _0\varPsi \approx \left( \frac{1}{2\mathcal{M}'} g^{\alpha \beta }\partial '_{\alpha }\partial '_{\beta } + \mathcal{M}\phi ^{(\mathrm g)} + n e\phi \right) \varPsi $ , where $\phi ^{(\mathrm g)} =\sqrt{g_{00}}$ and $\mathcal{M}'=\mathcal{M}/\phi ^{(\mathrm g)} $ , the correctness of the gravitational  contribution to the potential having been verified to linear order $m\phi ^{(\mathrm g)} $ in the thermal-neutron beam interferometry experiment due to Colella et al. Setting $n=2$ and regarding $\varPsi $ as the quasi-particle wave function, or order parameter, we obtain the generalization of the fundamental macroscopic Ginzburg-Landau equation of superconductivity to curved space–time. Conservation of probability and electrical current requires both electromagnetic gauge and space–time  coordinate conditions to be imposed, which exemplifies the gravito-electromagnetic analogy, particularly in the stationary case, when div ${{\varvec{A}}}=\hbox {div}{{\varvec{A}}}^{(\mathrm g)}=0$ , where ${{\varvec{A}}}^{\alpha }=-A^{\alpha }$ and ${{\varvec{A}}}^{(\mathrm g)\alpha }=-\phi ^{(\mathrm g)}g^{0\alpha }$ . The quantum-cosmological Schrödinger  (Wheeler–DeWitt) equation is also discussed in the $\mathcal{D}$ -dimensional  mini-superspace idealization, with particular regard to the vacuum potential $\mathcal V$ and the characteristics of the ground state, assuming a gravitational  Lagrangian   $L_\mathcal{D}$ which contains higher-derivative  terms up to order $\mathcal{R}^4$ . For the heterotic superstring theory  , $L_\mathcal{D}$ consists of an infinite series in $\alpha '\mathcal{R}$ , where $\alpha '$ is the Regge slope parameter, and in the perturbative approximation $\alpha '|\mathcal{R}| \ll 1$ , $\mathcal V$ is positive semi-definite for $\mathcal{D} \ge 4$ . The maximally symmetric ground state satisfying the field equations is Minkowski  space for $3\le {\mathcal {D}}\le 7$ and anti-de Sitter  space for $8 \le \mathcal {D} \le 10$ .  相似文献   

18.
Previous works have been made on the improvement of selectivity of ion exchange membranes using adsorption of polyelectrolyte on the surface of the materials. The modification of the surface material in the case of an anion exchange membrane concerns the hydrophilic/hydrophobic balance properties and its relationship with the hydration state. Starting from this goal, the AMX membrane has been modified, in this work, by adsorption of polyethyleneimine on its surface. Many conditions of modification of the AMX membrane surface were studied. A factorial experimental design was used for determining the influent parameters on the AMX membrane modification. The results obtained have shown that the initial concentration of polyethyleneimine and the pH of solution were the main influent parameters on the adsorption of polyethyleneimine on the membrane surface. Competitive ion exchange reactions were studied for the modified and the unmodified membrane involving $ {\text{C}}{{\text{l}}^{ - }} $ , $ {\text{NO}}_3^{ - } $ and $ {\text{SO}}_4^{{2 - }} $ ions. All experiments were carried out at constant concentration of 0.3?mol?L?1 and at 25?°C. Ion exchange isotherms for the binary systems $ \left( {{\text{C}}{{\text{l}}^{ - }}/{\text{NO}}_3^{ - }} \right) $ , $ \left( {{\text{C}}{{\text{l}}^{ - }}/{\text{SO}}_4^{{2 - }}} \right) $ and $ \left( {{\text{NO}}_3^{ - }/{\text{SO}}_4^{{2 - }}} \right) $ were studied. The obtained results show that chloride was the most sorbed and the selectivity order both for the modified membrane and the unmodified one is: $ {\text{Cl}} > {\text{NO}}_3^{ - } > {\text{SO}}_4^{{2 - }} $ , under the experimental conditions. Selectivity coefficients $ {\text{K}}_{{{\text{C}}{{\text{l}}^{ - }}}}^{{{\text{NO}}_3^{ - }}} $ , $ {\text{K}}_{{2{\text{C}}{{\text{l}}^{ - }}}}^{{{\text{SO}}_4^{{2 - }}}} $ and $ {\text{K}}_{{2{\text{NO}}_3^{ - }}}^{{{\text{SO}}_4^{{2 - }}}} $ for the three binary systems and for the two membranes were determined. It was also observed that for the modified membrane the selectivity towards sulfate ion decrease and the modified membrane became more selective towards monovalent anions.  相似文献   

19.
A search for double electron capture of 106Cd was performed at the Modane Underground Laboratory (4800 m w.e.) using a low-background and high-sensitivity multidetector spectrometer TGV-2 (Telescope Germanium Vertical). New limits on β +/EC, EC/EC decays of 106Cd were obtained from preliminary calculations of experimental data accumulated for 4800 h of measurement of 10 g of 106Cd with enrichment of 75%. They are > 9.1 × 1018 yr, > 1.9 × 1019 yr for transitions to the first 2+, 511.9 keV excited state of 106Pd, and > 1.3 × 1019 yr, > 6.2 × 1019 yr for transitions to the ground 0+ state of 106Pd. All limits are given at 90% C.L. The text was submitted by the authors in English.  相似文献   

20.
We employ the two independent Casimir operators of the Poincaré group, the squared four-momentum, p2, and the squared Pauli-Lubanski vector, W2, in the construction of a covariant mass m, and spin- projector in the four-vector spinor, ψμ. This projector provides the basis for the construction of an interacting Lagrangian that describes a causally propagating spin- particle coupled to the electromagnetic field by a gyromagnetic ratio of .  相似文献   

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