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1.
The branching ratios and differential distributions for the four-leptonic decays \({B^ - } \to {\mu ^ + }{\mu ^ - }{\bar v_e}{e^ - }\), \({B^ - } \to {e^ + }{e^ - }{\bar v_\mu }{\mu ^ - }\), and \({B^ - } \to {\mu ^ + }{\bar v_\mu }{\mu ^ - }{\mu ^ - }\) are calculated within the Standard Model. The branching ratios for the rare decays Bd,se+e?μ+μ? and Bd,sμ+μ?μ+μ? are estimated. Methods for testing the lepton universality in rare multileptonic decays of charged and neutral B mesons are proposed.  相似文献   

2.
The optical gain of He-Ne discharges for the laser wave-length of 6328 AE is investigated experimentally. The measurements are performed in two independent methods, which both give the same results. The gain of the He-Ne discharge is measured for a number of discharge tubes with different tube-lengthsl and tube-diametersD. The experiments show that the maximum gain? 0 is a function of tube-length and-diameter:?G 0(l,D) ?
$$\hat G_0 (l,D) \cong \left[ {1 + 0,5\left( {\frac{{D_0 }}{D}} \right)^{1,4} } \right]^{{l \mathord{\left/ {\vphantom {l {l_0 }}} \right. \kern-\nulldelimiterspace} {l_0 }}} $$  相似文献   

3.
Using the helicity formalism, we calculate the combined angular distribution function of the two gamma photons and the electron in the cascade process \({\bar{p}p}\to{}^{3}{D}_{2}\to\chi_{J}+\gamma_{1}\to(\psi +\gamma_{2})+\gamma_{1}\to({e}^{+}+{e}^{-})+\gamma_{1}+\gamma_{2}\) (J=0,1,2), when \({\bar{p}}\) and p are arbitrarily polarized. We also present the partially integrated angular distribution functions in six different cases. Our results show that by measuring the two-particle angular distribution of γ 1 and γ 2 and that of γ 1 and e ?, one can determine the relative magnitudes as well as the relative phases of all the helicity amplitudes in the two radiative decay processes 3 D 2χ J +γ 1 and χ J ψ+γ 2.  相似文献   

4.
Using the helicity formalism, we calculate the combined angular distribution function of the neutral pion (π 0) and the polarized electron (e ?) and photon (γ) produced in the triple cascade process \(\bar{p}+p\rightarrow{}^{1}D_{2}\rightarrow{}^{1}P_{1}+\gamma\rightarrow(\psi +\pi^{0})+\gamma \rightarrow(e^{-}+e^{+})+\pi^{0}+\gamma\), when \(\bar{p}\) and p are unpolarized. We also present the partially integrated angular distribution functions in three different cases where the combined angular distribution function of the three particles is integrated over the direction of one of the particles. Our results show that by measuring the two-particle angular distribution of the electron and the photon with the polarization of either particle, one can determine the relative magnitudes as well as the relative phases of all the angular-momentum helicity amplitudes in the two decay processes 1 D 21 P 1+γ and 1 P 1ψ+π 0.  相似文献   

5.
Rather than sticking to the full U(3)3 approximate symmetry normally invoked in Minimal Flavour Violation, we analyze the consequences on the current flavour data of a suitably broken U(2)3 symmetry acting on the first two generations of quarks and squarks. A definite correlation emerges between the ΔF=2 amplitudes \(\mathcal{M}( K^{0} \to \bar{K}^{0} )\), \(\mathcal{M}( B_{d} \to \bar{B}_{d} )\) and \(\mathcal{M}( B_{s} \to \bar{B}_{s} )\), which can resolve the current tension between \(\mathcal{M}( K^{0} \to \bar{K}^{0} )\) and \(\mathcal{M}( B_{d} \to \bar{B}_{d} )\), while predicting \(\mathcal{M}( B_{s}\to \bar{B}_{s} )\). In particular, the CP violating asymmetry in B s ψφ is predicted to be positive S ψφ =0.12±0.05 and above its Standard Model value (S ψφ =0.041±0.002). The preferred region for the gluino and the left-handed sbottom masses is below about 1÷1.5 TeV. An existence proof of a dynamical model realizing the U(2)3 picture is outlined.  相似文献   

6.
In this paper, we discuss the coherence of the reduced state in system H A ?H B under taking different quantum operations acting on subsystem H B . Firstly, we show that for a pure bipartite state, the coherence of the final subsystem H A under the sum of two orthonormal rank 1 projections acting on H B is less than or equal to the sum of the coherence of the state after two orthonormal projections acting on H B , respectively. Secondly, we obtain that the coherence of reduced state in subsystem H A under random unitary channel \({\Phi }(\rho )={\sum }_{s}\lambda _{s}U_{s}\rho U_{s}^{\ast }\) acting on H B , is equal to the coherence of the state after each operation \({\Phi }_{s}(\rho )=\lambda _{s}U_{s}\rho U_{s}^{\ast }\) acting on H B for every s. In addition, for general quantum operation \({\Phi }(\rho )={\sum }_{s}F_{s}\rho F_{s}^{\ast }\) on H B , we get the relation
$$ C\left (\left ((I\otimes {\Phi })\rho ^{AB}\right )^{A}\right )\leq \sum \limits _{s}C\left (\left ((I\otimes {\Phi }_{s})\rho ^{AB}\right )^{A}\right ). $$
  相似文献   

7.
The quantum-statistical properties of states of an electromagnetic field of general superpositions of coherent states of the form of N α,β(α?+e iξ β? are investigated. Formulas for the fluctuations (variances) of Hermitian trigonometric phase field operators ? ≡ côs φ, ? ≡ sîn φ (the so-called “Susskind–Glogower operators”) are found. Expressions for the rigorous uncertainty relations (Cauchy inequalities) for operators of the number of photons and trigonometric phase operators, as well as for operators ? and ?, are found and analyzed. The states of amplitude \({N_{\alpha ,\beta }}\left( {\left| {{{\sqrt {ne} }^{i\varphi }}\rangle + {e^{i\xi }}\left| {{{\sqrt {{n_\beta }e} }^{i\varphi }}\rangle } \right.} \right.} \right)\), φ = φα = φβ, and phase \({N_{\alpha ,\beta }}\left( {\left| {{{\sqrt {ne} }^{i{\varphi _\alpha }}}\rangle + {e^{i\xi }}\left| {{{\sqrt {ne} }^{i{\varphi _\beta }}}\rangle } \right.} \right.} \right)\), n = n α = n β, superpositions of coherent states are considered separately. The types of quantum superpositions of meso- and macroscales (n α, n β » 1) are found for which the sines and/or cosines of the phase of the field can be measured accurately, since, under certain conditions, the quantum fluctuations of these quantities are close to zero. A simultaneous accurate measurement of cosφ and sinφ is possible for amplitude superpositions, while an accurate measurement of one of these trigonometric phase functions is possible in the case of certain phase superpositions. Amplitude superpositions of coherent states with a vacuum state are quantum states of the field with a “maximum” level of the quantum uncertainty both in the case of a mesoscopic scale and in the case of a macroscopic scale of the field with an average number of photons n α/β ≈ 0, n β/α » 1.  相似文献   

8.
The emergence of transverse polarization of the lepton in the decay processes B0D?l+νl and \(B^ + \to \bar D^0 l + \nu _l \) for l = τ, μ is studied on the basis of the Standard Model in the leading approximation of heavy-quark effective theory. It is shown that a nonzero transverse polarization appears owing to electromagnetic final-state interactions at the one-loop level. Diagrams involving D and D* mesons in the intermediate state and making a nonzero contribution to the transverse polarization of the outgoing lepton are considered. If only these mesons are taken into account in evaluating the mean values of the τ-lepton polarization in the decays B0D?τ+ντ and \(B^ + \to \bar D^0 \tau ^ + \nu _\tau \), the results are 2.60×10-3 and ?1.59×10?3, respectively. The corresponding values of the transverse muon polarization averaged over the Dalitz plot are 2.97×10?4 and-6.79×10?4.  相似文献   

9.
The Neumann Schrödinger operator \(\mathcal{L}\) is considered on a thin 2D star-shaped junction, composed of a vertex domain Ωint and a few semi-infinite straight leads ω m , m = 1, 2, ..., M, of width δ, δ ? diam Ωint, attached to Ωint at Γ ? ?Ωint. The potential of the Schrödinger operator l ω on the leads vanishes, hence there are only a finite number of eigenvalues of the Neumann Schrödinger operator L int on Ωint embedded into the open spectral branches of l ω with oscillating solutions χ ±(x, p) = \(e^{ \pm iK_ + x} e_m \) of l ω χ ± = p 2 χ ±. The exponent of the open channels in the wires is
$K_ + (\lambda ) = p\sum\limits_{m = 1}^M {e^m } \rangle \langle e^m = \sqrt \lambda P_ + $
, with constant e m , on a relatively small essential spectral interval Δ ? [0, π 2 δ ?2). The scattering matrix of the junction is represented on Δ in terms of the ND mapping
$\mathcal{N} = \frac{{\partial P_ + \Psi }}{{\partial x}}(0,\lambda )\left| {_\Gamma \to P_ + \Psi _ + (0,\lambda )} \right|_\Gamma $
as
$S(\lambda ) = (ip\mathcal{N} + I_ + )^{ - 1} (ip\mathcal{N} - I_ + ), I_ + = \sum\limits_{m = 1}^M {e^m } \rangle \langle e^m = P_ + $
. We derive an approximate formula for \(\mathcal{N}\) in terms of the Neumann-to-Dirichlet mapping \(\mathcal{N}_{\operatorname{int} } \) of L int and the exponent K ? of the closed channels of l ω . If there is only one simple eigenvalue λ 0 ∈ Δ, L intφ0 = λ 0φ0 then, for a thin junction, \(\mathcal{N} \approx |\vec \phi _0 |^2 P_0 (\lambda _0 - \lambda )^{ - 1} \) with
$\vec \phi _0 = P_ + \phi _0 = (\delta ^{ - 1} \int_{\Gamma _1 } {\phi _0 (\gamma )} d\gamma ,\delta ^{ - 1} \int_{\Gamma _2 } {\phi _0 (\gamma )} d\gamma , \ldots \delta ^{ - 1} \int_{\Gamma _M } {\phi _0 (\gamma )} d\gamma )$
and \(P_0 = \vec \phi _0 \rangle |\vec \phi _0 |^{ - 2} \langle \vec \phi _0 \),
$S(\lambda ) \approx \frac{{ip|\vec \phi _0 |^2 P_0 (\lambda _0 - \lambda )^{ - 1} - I_ + }}{{ip|\vec \phi _0 |^2 P_0 (\lambda _0 - \lambda )^{ - 1} + I_ + }} = :S_{appr} (\lambda )$
. The related boundary condition for the components P +Ψ(0) and P +Ψ′(0) of the scattering Ansatz in the open channel \(P_ + \Psi (0) = (\bar \Psi _1 ,\bar \Psi _2 , \ldots ,\bar \Psi _M ), P_ + \Psi '(0) = (\bar \Psi '_1 , \bar \Psi '_2 , \ldots , \bar \Psi '_M )\) includes the weighted continuity (1) of the scattering Ansatz Ψ at the vertex and the weighted balance of the currents (2), where
$\frac{{\bar \Psi _m }}{{\bar \phi _0^m }} = \frac{{\delta \sum\nolimits_{t = 1}^M { \bar \Psi _t \bar \phi _0^t } }}{{|\vec \phi _0 |^2 }} = \frac{{\bar \Psi _r }}{{\bar \phi _0^r }} = :\bar \Psi (0)/\bar \phi (0), 1 \leqslant m,r \leqslant M$
(1)
,
$\sum\limits_{m = 1}^M {\bar \Psi '_m } \bar \phi _0^m + \delta ^{ - 1} (\lambda - \lambda _0 )\bar \Psi /\bar \phi (0) = 0$
(1)
. Conditions (1) and (2) constitute the generalized Kirchhoff boundary condition at the vertex for the Schrödinger operator on a thin junction and remain valid for the corresponding 1D model. We compare this with the previous result by Kuchment and Zeng obtained by the variational technique for the Neumann Laplacian on a shrinking quantum network.
  相似文献   

10.
We study the prospects to measure the CP-sensitive triple-product asymmetries in neutralino production \(e^{+} e^{-} \to\tilde{\chi}^{0}_{i}\tilde{\chi}^{0}_{1}\) and subsequent leptonic two-body decays \(\tilde{\chi}^{0}_{i} \to \tilde{\ell}_{R} \ell\), \(\tilde{\ell}_{R} \to \tilde{\chi}^{0}_{1} \ell\), for ?=e,μ, within the Minimal Supersymmetric Standard Model. We include a full detector simulation of the International Large Detector for the International Linear Collider. The simulation was performed at a center-of-mass energy of \(\sqrt{s}=500\) GeV, including the relevant Standard Model background processes, a realistic beam energy spectrum, beam backgrounds and a beam polarization of 80% and ?60% for the electron and positron beams, respectively. In order to effectively disentangle different signal samples and reduce SM and SUSY backgrounds we apply a method of kinematic reconstruction. Assuming an integrated luminosity of 500 fb?1 collected by the experiment and the performance of the current ILD detector, we arrive at a relative measurement accuracy of 10% for the CP-sensitive asymmetry in our scenario. We demonstrate that our method of signal selection using kinematic reconstruction can be applied to a broad class of scenarios and it allows disentangling processes with similar kinematic properties.  相似文献   

11.
We interest to investigate of the quasi-three-body decays of B0 meson to \({f_0}(980){K^ + }{\pi ^ - }({f_0}(980) \to \pi \pi )\) and \({\bar D_1}{(2420)^0}{\pi ^ + }{\pi ^ - }(\bar D_1^0) \to D{^{*-} }{\pi ^ + }\). The analysis of mentioned four-body decays is such as to factorize into the three-body decay and several channels observed. Hadronic three-body decays include both non-resonant and resonant contributions, on the basis of the factorization approach. In the case of B0 to vector pseudoscalar states appeared in factorized terms, the B* pole contribution is considered. Hence the matrix element of the B* → D1 weak transition and strong vertex is computed. Therefore the theoretical values are (1.418 ± 0.21) × 10?6 and (1.44 ± 0.2) × 10?4, while the experimental results of them are \((1.4_{-0.6}^{+0.5})\times10^{-6}\), respectively. Comparing computational analysis values with experimental values show that our results are in agreement with them.  相似文献   

12.
The decay of an excited state by the emission of twoγ-quanta (γ γ-transitions) or two conversion electrons (e e-transitions) or oneγ-quantum and one conversion electron (γ e-transitions) is expected as a second order radiation process. The decay of Ag109m was examined for such events using a special arrangement of two NaJ-scintillation counters in coincidence. The energies of coincident quanta were displayed on the two axes of an “X-Y”-Oscilloscope respectively. For the ratio ofγ γ-transitions to one-quantum transitions an upper limit of\(\frac{{W_{\gamma \gamma } }}{{W_\gamma }} \leqq 1,9 \cdot 10^{ - 5} \) was obtained. Furthermore theγ-spectrum in coincidence withK X-rays was studied. From these measurementse e- andγ e-transition rates can be calculated for the case ofK shell conversion. The results obtained are:
$$\frac{{W_{^e K^e K} }}{{W_\gamma }} = \left( {8,1_{ - 1,7}^{ + 0,6} } \right) \cdot 10^{ - 3} and\frac{{W_{\gamma ^e K} }}{{W_\gamma }}< 1,5 \cdot 10^{ - 3} .$$  相似文献   

13.
The NA48/2 experiment reports the first observation of the rare decay K±π±π0e+e?, based on about 2000 candidates from 2003 data. The preliminary branching ratio in the full kinematic region is \(\mathcal {B}(K^{\pm } \to \pi ^{\pm }\pi ^{0}e^{+}e^{-})=(4.06\pm 0.17)\cdot 10^{-6}\). A sample of 4.687 × 106\(K^{\pm }\to \pi ^{\pm }{\pi ^{0}_{D}}\) events collected in 2003/4 is analyzed to search for the dark photon (\(A^{\prime }\)) via the decay chain K±π±π0, \(\pi ^{0}\to \gamma A^{\prime }\), \(A^{\prime }\to e^{+}e^{-}\). No signal is observed, limits in the plane mixing parameter ε2 versus its mass \(m_{A^{\prime }}\) are reported.  相似文献   

14.
The thermal conductivity of a trapped dipolar Bose condensed gas is calculated as a function of temperature in the framework of linear response theory. The contributions of the interactions between condensed and noncondensed atoms and between noncondensed atoms in the presence of both contact and dipole-dipole interactions are taken into account to the thermal relaxation time, by evaluating the self-energies of the system in the Beliaev approximation. We will show that above the Bose-Einstein condensation temperature (T?>?T BEC ) in the absence of dipole-dipole interaction, the temperature dependence of the thermal conductivity reduces to that of an ideal Bose gas. In a trapped Bose-condensed gas for temperature interval k B T?<<?n 0 g B E p ?<<?k B T (n 0 is the condensed density and g B is the strength of the contact interaction), the relaxation rates due to dipolar and contact interactions between condensed and noncondensed atoms change as \( {\tau}_{dd12}^{-1}\propto {e}^{-E/{k}_BT} \) and τ c12?∝?T ?5, respectively, and the contact interaction plays the dominant role in the temperature dependence of the thermal conductivity, which leads to the T ?3 behavior of the thermal conductivity. In the low-temperature limit, k B T?<<?n 0 g B , E p ?>>?k B T, since the relaxation rate \( {\tau}_{c12}^{-1} \) is independent of temperature and the relaxation rate due to dipolar interaction goes to zero exponentially, the T 2 temperature behavior for the thermal conductivity comes from the thermal mean velocity of the particles. We will also show that in the high-temperature limit (k B T?>?n 0 g B ) and low momenta, the relaxation rates \( {\tau}_{c12}^{-1} \) and \( {\tau}_{dd12}^{-1} \) change linearly with temperature for both dipolar and contact interactions and the thermal conductivity scales linearly with temperature.  相似文献   

15.
The amplitudes obtained from the effective chiral Lagrangian with anomalous terms based on hidden local symmetry are applied to the evaluation of the partial widths of the decays ω → 2π+2π?π0 and ωπ+π?3π0. Combining the Okubo-Zweig-Iizuka rule, applied to the five-pion final state, with the Adler condition of vanishing of the amplitude at the vanishing of four-momentum of any final pion in the chiral limit, the ? → 2π+2π?π0 and ?π+π?3π0 decay amplitudes are also calculated. The partial widths of the above decays are evaluated, and the resonance excitation curves in e+e? annihilation are obtained, assuming reasonable particular relations among the free parameters characterizing the anomalous terms of the Lagrangian. The evaluated branching ratios \(Br_{\phi \to \pi + \pi - 3\pi ^0 } \approx 2 \times 10^{ - 7} \) and \(Br_{\phi \to 2\pi + 2\pi - \pi ^0 } \approx 5 \times 10^{ - 7} \) are such that with the luminosity L = 500 pb?1, attained at the DAΦNE ? factory, one may already possess about 1340 events of the decays ? → 5π.  相似文献   

16.
An electric Molecular-Beam-Resonance-Spectrometer has been used to measure simultanously the Zeeman- and Stark-effect splitting of the hyperfine structure of39K19 F. Electric four pole lenses served as focusing and refocusing fields of the spectrometer. A homogenous magnetic field (Zeeman field) was superimposed to the electric field (Stark field) in the transition region of the apparatus. The observed (Δm J =±1)-transitions were induced electrically. Completely resolved spectra of KF in theJ=1 rotational state have been measured. The obtained quantities are: The electric dipolmomentμ e l of the molecul forv=0,1 and 2; the rotational magnetic dipolmomentμ J forv=0,1; the difference of the magnetic shielding (σ ? σ) by the electrons of both nuclei as well as the difference of the molecular susceptibility (ξ ? ξ). The numerical values are
$$\begin{array}{*{20}c} {\mu _{e1} = 8,585(4)deb,} \\ {\frac{{(\mu _{e1} )_{\upsilon = 1} }}{{(\mu _{e1} )_{\upsilon = 0} }} = 1,0080,} \\ {{{\mu _J } \mathord{\left/ {\vphantom {{\mu _J } J}} \right. \kern-\nulldelimiterspace} J} = ( - )2352(10) \cdot 10^{ - 6} \mu _B ,} \\ {(\sigma _ \bot - \sigma _\parallel )F = ( - )2,19(9) \cdot 10^{ - 4} ,} \\ {(\sigma _ \bot - \sigma _\parallel )K = ( - )12(9) \cdot 10^{ - 4} ,} \\ {(\xi _ \bot - \xi _\parallel ) = 3 (1) \cdot 10^{ - 30} {{erg} \mathord{\left/ {\vphantom {{erg} {Gau\beta ^2 }}} \right. \kern-\nulldelimiterspace} {Gau\beta ^2 }}} \\ \end{array} $$  相似文献   

17.
In the diffraction dissociation of π? into μ+μ?π? on a Cu nucleus at 50 GeV/c, the cross section \(\sigma _{\mu ^ + \mu ^ - \pi ^ - } \) for the 1+S(ρ0π) wave was measured. The branching ratio of ρ0→μ+μ? could be calculated from the ratio of this and the corresponding cross sections in the diffraction dissociation of π? into π+π?π?. The obtained value \(BR_{\rho ^0 \to \mu ^ + \mu ^ - } = (4.6 \pm 0.2_{stat^ \pm } \pm 0.2_{syst} )10^{ - 5} \) is in good agreement with the branching ratio \(BR_{\rho ^0 \to e^ + e^ - } \) , as expected ifeμ universality holds.  相似文献   

18.
19.
We report on two sensitive tests of lepton universality carried out by the 4 LEP experiments at the Z0 pole. From measurements of the τ polarization in e+ e?τ + τ ?, the ratios of the vector and axial vector coupling constants of the electron and the tau lepton to the weak neutral current are obtained to beg v e /g a e =0.066±0.015 andg V τ /g A τ =0.070±0.009 respectively. From measurement of the τ lifetime and the τ leptonic branching ratios, the ratio of the coupling constants describing weak leptonic decays of the τ and the μ is measured to beG τ /G μ =0.996±0.008.  相似文献   

20.
An electric molecular beam resonance spectrometer has been used to measure simultaneously the Zeeman- and Stark-effect splitting of the hyperfine structure of133Cs19F. Electric four pole lenses served as focusing and refocusing fields of the spectrometer. A homogenous magnetic field (Zeeman field) was superimposed to the electric field (Stark field) in the transition region of the apparatus. Electrically induced (Δ m J =±1)-transitions have been measured in theJ=1 rotational state, υ=0, 1 vibrational state. The obtained quantities are: The electric dipolmomentμ el of the molecule for υ=0, 1; the rotational magnetic dipolmomentμ J for υ=0, 1; the anisotropy of the magnetic shielding (σ -σ‖) by the electrons of both nuclei as well as the anisotropy of the molecular susceptibility (ξ -ξ‖), the spin rotational interaction constantsc Cs andc F, the scalar and the tensor part of the nuclear dipol-dipol interaction, the quadrupol interactioneqQ for υ=0, 1. The numerical values are:
$$\begin{gathered} \mu _{el} \left( {\upsilon = 0} \right) = 73878\left( 3 \right)deb \hfill \\ \mu _{el} \left( {\upsilon = 1} \right) - \mu _{el} \left( {\upsilon = 0} \right) = 0.07229\left( {12} \right)deb \hfill \\ \mu _J /J\left( {\upsilon = 0} \right) = - 34.966\left( {13} \right) \cdot 10^{ - 6} \mu _B \hfill \\ \mu _J /J\left( {\upsilon = 1} \right) = - 34.823\left( {26} \right) \cdot 10^{ - 6} \mu _B \hfill \\ \left( {\sigma _ \bot - \sigma _\parallel } \right)_{Cs} = - 1.71\left( {21} \right) \cdot 10^{ - 4} \hfill \\ \left( {\sigma _ \bot - \sigma _\parallel } \right)_F = - 5.016\left( {15} \right) \cdot 10^{ - 4} \hfill \\ \left( {\xi _ \bot - \xi _\parallel } \right) = 14.7\left( {60} \right) \cdot 10^{ - 30} erg/Gau\beta ^2 \hfill \\ c_{cs} /h = 0.638\left( {20} \right)kHz \hfill \\ c_F /h = 14.94\left( 6 \right)kHz \hfill \\ d_T /h = 0.94\left( 4 \right)kHz \hfill \\ \left| {d_s /h} \right|< 5kHz \hfill \\ eqQ/h\left( {\upsilon = 0} \right) = 1238.3\left( 6 \right) kHz \hfill \\ eqQ/h\left( {\upsilon = 1} \right) = 1224\left( 5 \right) kHz \hfill \\ \end{gathered} $$  相似文献   

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