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1.
In this paper, we have improved the calculation of the relic
gravitational waves (RGW) in two aspects. First, we investigate the
transfer function by taking into consideration the
redshift-suppression effect, the accelerating expansion effect, the
damping effect of free-streaming relativistic particles, and the
damping effect of cosmic phase transition, and give a simple
approximate analytic expression, which clearly illustrates the
dependence on the cosmological parameters. Second, we develop a
numerical method to calculate the primordial power spectrum of RGW in
a very wide frequency range, where the observed constraints on
$n_{\rm s}$ (the scalar spectral index) and $P_{\rm S}(k_0)$ (the
amplitude of primordial scalar spectrum) and the Hamilton--Jacobi
equation are used. This method is applied to two kinds of
inflationary models, which satisfy the current constraints on $n_{\rm
s}$, $\alpha$ (the running of $n_{\rm s}$) and $r$ (the
tensor--scalar ratio). We plot them in the $r-{\it\Omega}_{\rm g}$
diagram, where ${\it\Omega}_{\rm g}$ is the strength of RGW, and
study their measurements from the cosmic microwave background (CMB)
experiments and laser interferometers. 相似文献
2.
Takamichi Terao 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(10):209
The hopping electron model on the Kagome lattice was investigated by kinetic Monte Carlo simulations, and the non-equilibrium nature of the system was studied. We have numerically confirmed that aging phenomena are present in the autocorrelation function \hbox{$C \, \left({t,t_{W} } \right)$}C?t,tW)( of the electron system on the Kagome lattice, which is a geometrically frustrated lattice without any disorder. The waiting-time distributions \hbox{$p\left(\tau \right)$}pτ)( of hopping electrons of the system on Kagome lattice has been also studied. It is confirmed that the profile of \hbox{$p\, \left(\tau \right)$}p?τ)( obtained at lower temperatures obeys the power-law behavior, which is a characteristic feature of continuous time random walk of electrons. These features were also compared with the characteristics of the Coulomb glass model, used as a model of disordered thin films and doped semiconductors. This work represents an advance in the understanding of the dynamics of geometrically frustrated systems and will serve as a basis for further studies of these physical systems. 相似文献
3.
Using a single-mode approximation, we carry out the entanglement measures, e.g., the negativity and von Neumann entropy when a tetrapartite generalized GHZ state is treated in a noninertial frame, but only uniform acceleration is considered for simplicity. In terms of explicit negativity calculated, we notice that the difference between the algebraic average $\pi_{4}$ and geometric average $\varPi_{4}$ is very small with the increasing accelerated observers and they are totally equal when all four qubits are accelerated simultaneously. The entanglement properties are discussed from one accelerated observer to all four accelerated observers. It is shown that the entanglement still exists even if the acceleration parameter $r$ goes to infinity. It is interesting to discover that all 1-1 tangles are equal to zero, but 1-3 and 2-2 tangles always decrease when the acceleration parameter $r$ increases. We also study the von Neumann entropy and find that it increases with the number of the accelerated observers. In addition, we find that the von Neumann entropy $S_{\text{ABCDI}}$, $S_{\text{ABCIDI}}$, $S_{\text{ABICIDI}}$ and $S_{\text{AIBICIDI}}$ always decrease with the controllable angle $\theta$, while the entropies $S_{3-3~\rm non}$, $S_{3-2~\rm non}$, $S_{3-1~\rm non}$ and $S_{3-0~\rm non}$ first increase with the angle $\theta$ and then decrease with it. 相似文献
4.
A. Kobakhidze L. Mersini-Houghton 《The European Physical Journal C - Particles and Fields》2007,49(3):869-873
We show that a unique, most probable and stable solution for the wavefunction of the universe, with a very small cosmological
constant , can be predicted from the supersymmetric minisuperspace with N vacua of the landscape of string theory without referring
to the anthropic principle. Due to the nearest neighbor tunneling in moduli space lattice, the N-fold degeneracy of the vacua
is lifted and a discrete spectrum of bound state levels over the whole minisuperspace emerges. Supersymmetry is spontaneously
broken by these bound states, with discrete non-zero energy levels , s=1,2,...
PACS 98.80.Qc; 11.25.Wx 相似文献
5.
A straightforward method for calculating the quantum-field functions in terms of the Yang–Mills gauge theory is proposed. The Green functions of a free gluon in the n μ $n_\mu \dot A_\mu = 0{\text{ }}and{\text{ }}\partial _\mu \dot A_\mu = 0$ gauges are calculated using the method. New formulas are derived that have no analogy in the literature. 相似文献
6.
This paper presents a model to describe alternating current (AC) conductivity of DNA sequences, in which DNA is considered as a one-dimensional (1D) disordered system, and electrons transport via hopping between localized states. It finds that AC conductivity in DNA sequences increases as the frequency of the external electric field rises, and it takes the form of σac (ω)~ω 2\ln 2(1/ω). Also AC conductivity of DNA sequences increases with the increase of temperature, this phenomenon presents characteristics of weak temperature-dependence. Meanwhile, the AC conductivity in an off-diagonally correlated case is much larger than that in the uncorrelated case of the Anderson limit in
low temperatures, which indicates that the off-diagonal correlations in DNA sequences have a great effect on the AC conductivity, while at high temperature the off-diagonal correlations no longer play a vital role in electric transport. In addition, the proportion of nucleotide pairs p also plays an important role in AC electron
transport of DNA sequences. For p < 0.5, the conductivity of DNA sequence decreases with the increase of p, while for p ≥ 0.5, the conductivity increases with the increase of p. 相似文献
7.
We prove that AB site percolation occurs on the line graph of the square lattice when $p \in (1 - \sqrt {1 - p_c } ,\sqrt {1 - p_c } )$ , where p c is the critical probability for site percolation in $\mathbb{Z}^2$ . Also, we prove that AB bond percolation does not occur on $\mathbb{Z}^2$ for p = $\frac{1}{2}$ . 相似文献
8.
9.
SUPERCONDUCTING TRANSITION TEMPERATURES AND NORMAL-STATE ELECTRICAL RESISTIVITIES OF Tm1-xPrxBa2Cu3O7-δ 下载免费PDF全文
曹效文 《物理学报(海外版)》1994,3(8):583-588
Superconducting transition temperature Tc and normal-state electrical resistivities ρ of the Tm1-xPrxBa2Cu3O7-δ system have been measured. The results indicate that Tc remains constant for x = 0 to 0.08 before it drops steadily with higher x. Following the Abrikosov-Gor'kov model, a total suppression of superconductivity occurs at a critical Pr concentration xcr≈0.56. It is found for the first time, as far as we know, that the logarithmic resistivity at 270 K increases linearly with increasing x, yielding ρ= ρ0eax. Judging from the relation between dρ/dT and x, a metal to insulator transition occurs just beyond xcr. 相似文献
10.
Theoretical calculation of the quadratic Zeeman shift coefficient of the 3P0o clock state for strontium optical lattice clock 下载免费PDF全文
Benquan Lu 《中国物理 B》2022,31(4):43101-043101
In the weak-magnetic-field approximation, we derived an expression of quadratic Zeeman shift coefficient of $^3P^{\rm o}_0$ clock state for $^{88}$Sr and $^{87}$Sr atoms. By using this formula and the multi-configuration Dirac-Hartree-Fock theory, the quadratic Zeeman shift coefficients were calculated. The calculated values $C_2$ = $-23.38(5)$ MHz/T$^2$ for $^{88}$Sr and the $^3P^{\rm o}_0$, $F = 9/2$, $M_F = \pm9/2$ clock states for $^{87}$Sr agree well with the other available theoretical and experimental values, especially the most accurate measurement recently. In addition, the calculated values of the $^3P^{\rm o}_0$, $F = 9/2$, $M_F = \pm9/2$ clock states were also determined in our $^{87}$Sr optical lattice clock. The consistency with measurements verifies the validation of our calculation model. Our theory is also useful to evaluate the second-order Zeeman shift of the clock transition, for example, the new proposed $^1S_0$, $F = 9/2$, $M_F = \pm5/2$-${}^3P^{\rm o}_0$, $F = 9/2$, $M_F = \pm3/2$ transitions. 相似文献
11.
The observed rotation curves of low surface brightness (LSB) galaxies play an essential role in studying dark matter, and indicate the existence of a central constant density dark matter core. However, the cosmological N-body simulations of cold dark matter predict an inner cusped halo with a power-law mass density distribution, and cannot reproduce a central constant-density core. This phenomenon is called cusp-core problem. When dark matter is quiescent and satisfies the condition for hydrostatic equilibrium, the equation of state can be adopted to obtain the density profile in the static and spherically symmetric space-time. To address the cusp-core problem, we assume that the equation of state is independent of the scaling transformation. Its lower order approximation for this type of equation of state can naturally lead to a special case, i.e., \begin{document}$p=\zeta\rho+2\epsilon V_{\rm rot}^{2}\,\rho$\end{document} ![]()
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, where p and \begin{document}$\rho$\end{document} ![]()
![]()
represent the pressure and density, respectively, \begin{document}$V_{\rm rot}$\end{document} ![]()
![]()
depicts the rotation velocity of galaxy, and \begin{document}$\zeta$\end{document} ![]()
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and \begin{document}$ \epsilon$\end{document} ![]()
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are positive constants. It can obtain a density profile that is similar to the pseudo-isothermal halo model when \begin{document}$\epsilon$\end{document} ![]()
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is approximately 0.15. To obtain a more universally used model, let the equation of state include the polytropic model, i.e. \begin{document}$p= \frac{\zeta}{\rho_{0}^{s}}\rho^{1+s}+ 2\epsilon V_{\rm rot}^{2}\,\rho$\end{document} ![]()
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, from which we can obtain other types of density profiles, such as the profile that is nearly same as the Burkert profile, where s and \begin{document}$\rho_{0}$\end{document} ![]()
![]()
are positive constants. 相似文献
12.
Diffusion in narrow curved channels with dead-ends as in extracellular space in the biological tissues, e.g., brain, tumors, muscles, etc. is a geometrically induced complex diffusion and is relevant to different kinds of biological, physical, and chemical systems. In this paper, we study the effects of geometry and confinement on the diffusion process in an elliptical comb-like structure and analyze its statistical properties. The ellipse domain whose boundary has the polar equation $\rho \left( \theta \right)=\frac{b}{\sqrt {1-e^{2}\cos^{2}\theta } }$ with $0相似文献
13.
Connectivity correlations in three topological spaces of urban bus-transport networks in China 下载免费PDF全文
In this paper, an empirical investigation is presented, which focuses on unveiling the universality of connectivity correlations in three spaces (the route space, the stop geographical space and bus-transferring space) of urban bustransport networks (BTNs) in four major cities of China. The underlying features of the connectivity correlations are shown in two statistical ways. One is the correlation between the (weighted) average degree of all the nearest neighbouring vertices with degree k, (Knn^w,(k)) Knn(k), and k, and the other is the correlations between the assortativity coefficient r and, respectively, the network size N, the network diameter D, the averaged clustering coefficient C, and the averaged distance (l). The obtained results show qualitatively the same connectivity correlations of all the considered cities under all the three spaces. 相似文献
14.
H. Chamati S. Romano 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(2):249-254
Generalized xy lattice spin models consist of
three-component unit vectors, associated with a D-dimensional
lattice (say
), parameterized by usual spherical
angles (θk,φk), and interacting via a ferromagnetic
potential restricted to nearest neighbours, of the form
here epsilon is a positive quantity setting energy and
temperature scales. The models were recently introduced,
and proven to support an ordering transition taking place
at finite temperature when D=3; in turn, this transition had been
investigated by different techniques for p=2,3,4, and found to
belong to the same universality class as the xy model (i.e. p=1).
More recently, it was rigorously proven that for
sufficiently large p the transition becomes first order. Here we present
a detailed analysis of the transitional properties of this
class of models for selected values of p.
For p=8 simulation results showed a second order phase
transition belonging to the xy class of universality;
they suggested tricritical behaviour for p=12,
and gave evidence of first-order transitions for both p=16 and p=20. 相似文献
15.
V. R. Brown B. F. Gibson J. A. Carlson R. Schiavilla 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):289-291
The parity-non-conserving longitudinal asymmetry in proton-proton (p
p) elastic scattering is calculated in the lab energy range 0-350 MeV using contemporary, realistic strong-interaction potentials combined with a weak-interaction potential comprised of
- and
-meson exchanges as exemplified by the DDH model. Values for the
- and
-meson coupling constants,
and
, are determined from comparison with the measured asymmetries at 13.6 MeV, 45 MeV, and 221 MeV.Received: 30 September 2002, Published online: 22 October 2003PACS:
21.30.-x Nuclear forces - 24.80. + y Nuclear tests of fundamental interactions and symmetries - 25.40.Cm Elastic proton scattering 相似文献
16.
The transfer of the quantum correlation from two-mode nonclassical state field to the supercurrents in two distant SQUID rings 下载免费PDF全文
We have considered two distant mesoscopic superconducting quantum
interference device (SQUID) rings A and B in the presence of two-mode
nonclassical state fields and investigated the correlation of the
supercurrents in the two rings using the normalized correlation
function $C_{\rm AB}$. We show that when the parameter $\alpha$ is
very small for the separable state with the density matrix $\hat
{\rho } = (\left| {\alpha , - \alpha } \right\rangle \left\langle
{\alpha , - \alpha } \right| + \left| { - \alpha ,\alpha }
\right\rangle \left\langle { - \alpha ,\alpha } \right|) / 2$ and
entangled coherent state (ECS) $\left| u \right\rangle = N_1 (\left|
{\alpha , - \alpha } \right\rangle + \left| { - \alpha ,\alpha }
\right\rangle )$ fields, the dynamic behaviours of the normalized
correlation function $C_{\rm AB}$ are similar, but it is quite
different for the entangled coherent state $\left| {u}'
\right\rangle = N_2 (\left| {\alpha , - \alpha } \right\rangle -
\left| { - \alpha ,\alpha } \right\rangle )$ field. When the
parameter $\alpha $ is very large, the dynamic behaviours of $C_{\rm
AB}$ are almost the same for the separable state, entangled coherent
state $\left| u \right\rangle $ and $\left| {u}' \right\rangle $
fields. For the two-mode squeezed vacuum state field the maximum of
$C_{\rm AB}$ increases monotonically with the squeezing parameter
$r$, and as $r \to \infty $, $C_{\rm AB} \to 1$. This means that the
supercurrents in the two rings A and B are quantum mechanically
correlated perfectly. It is concluded that not all the quantum
correlations in the two-mode nonclassical state field can be
transferred to the supercurrents; and the transfer depends on the
state of the two-mode nonclassical state field prepared. 相似文献
17.
The analytical transfer matrix method (ATMM) is applied to
calculating the critical radius $r_{\rm c}$ and the dipole
polarizability $\alpha_{\rm d}$ in two confined systems: the hydrogen
atom and the Hulth\'{e}n potential. We find that there exists a
linear relation between $r_{\rm c}^{1/2}$ and the quantum number $n_{r}$
for a fixed angular quantum number $l$, moreover, the three bounds
of $\alpha_{\rm d}$ ($\alpha_{\rm d}^{K}$, $\alpha_{\rm d}^{B}$,
$\alpha_{\rm d}^{U}$) satisfy an inequality:
$\alpha_{\rm d}^{K}\leq\alpha_{\rm d}^{B}\leq\alpha_{\rm d}^{U}$. A comparison
between the ATMM, the exact numerical analysis, and the variational
wavefunctions shows that our method works very well in the systems. 相似文献
18.
19.
A. Capella C.A. Salgado D. Sousa 《The European Physical Journal C - Particles and Fields》2003,30(1):111-116
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
20.
Effect of R substitution on magnetic properties and magnetocaloric effects of La1-xRxFe11.5Si1.5 compounds with R=Ce, Pr and Nd 下载免费PDF全文
<正>Magnetic properties and magnetocaloric effects of La1-xRxFe1105 Si9105)(R=Pr,(0≤x≤0.5);R = Ce and Nd, (0≤x≤0.3)) compounds are investigated.Partially replacing La with R = Ce,Pr and Nd in La1-xRxFe11.5Si1.5 leads to a reduction in Curie temperature due to the lattice contraction.The substitution of R for La causes an enhancement in field-induced itinerant electron metamagnetic transition,which leads to a remarkable increase in magnetic entropy change△Sm and also in hysteresis loss.However,a high effective refrigerant capacity RCeff is still maintained in La1-xRxFe11.5Si1.5.In the present samples,a large△Sm and a high RCeff have been achieved simultaneously. 相似文献