共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
A Fokker–Planck equation describing the statistical properties of Brownian particles acted upon by long-range stochastic forces with power-law correlations is derived. In contrast with previous approaches (Wang, Phys. Rev. A 45 (1992) 2), it is shown that the distribution of Brownian particles after release from a point source is broader than Gaussian and described by a Fox function. Transport is shown to be ballistic at short times and either sub-diffusive or super-diffusive at large times. The imposition of occasional trapping events onto the Brownian dynamics can result in confined diffusion (d/dtx2→0) at long times when the mean trapping time is divergent. It is suggested that such dynamics describe protein motions in cell membranes. 相似文献
3.
Nan Zhang Ya-Bo Wu Jun-Wang Lu Chu-Wen Sun Li-Jie Shou Hai-Zhou Xu 《中国物理C(英文版)》2020,44(9):095107-095107-8
Based on the dynamics of single scalar field slow-roll inflation and the theory of reheating, we investigate the generalized natural inflationary (GNI) model. We introduce constraints on the scalar spectral index \begin{document}$n_{s}$\end{document} ![]()
![]()
and the tensor-to scalar ratio r for the \begin{document}$\Lambda$\end{document} ![]()
![]()
CDM \begin{document}$+r$\end{document} ![]()
![]()
model, according to the latest data from Planck 2018 TT, TE, EE+low E+lensing (P18) and BICEP2/Keck 2015 season (BK15), i.e., with \begin{document}$n_{s}=0.9659\pm0.0044$\end{document} ![]()
![]()
at 68% confidence level (CL), and \begin{document}$r<0.0623$\end{document} ![]()
![]()
at 95% CL. We find that the GNI model is favored by P18 and BK15 in the ranges \begin{document}$\log_{10}(f/M_{p})= 0.62^{+0.17}_{-0.18}$\end{document} ![]()
![]()
and \begin{document}$m=0.35^{+0.13}_{-0.23}$\end{document} ![]()
![]()
at 68% CL. In addition, the corresponding predictions of generalized and two-phase reheating are discussed. It follows that the parameter m has significant effect on the model behavior. 相似文献
4.
《Physics letters. [Part B]》1986,166(1):49-53
We calculate the dipole and quadropole moments, (ΔT/T)l l=1, 2, of the cosmic background radiation anisotropy due to scalar and tensor waves with power-law spectra, produced by quantum processes during a “generalized” inflationary era of the early universe. The observational bounds on (ΔT/T)l are used to give constraints on the parameters of the cosmological models. 相似文献
5.
6.
7.
8.
9.
10.
Español P Serrano M 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,59(6):6340-6347
We discuss theoretically the behavior of the velocity autocorrelation function in the dissipative particle dynamics (DPD) model. Two dynamical regimes are identified depending on the dimensionless model parameters. For low values of the dimensional friction, a mean field behavior is observed in which the kinetic theory for the DPD model provides good predictions. For high values of the friction, collective hydrodynamic effects are dominant. We have performed numerical simulations that validate the theory presented. 相似文献
11.
We investigate the observational constraints on three typical brane inflation models by considering the latest local measurement of the Hubble constant in the global fit. We also employ other observational data, including the Planck 2015 CMB data, the BICEP2/Keck Array B-mode data, and the baryon acoustic oscillations data, in our analysis. Previous studies have shown that the addition of the latest local H_0 measurement favors a larger spectral index, and can exert a significant influence on the model selection of inflation. In this work, we investigate its impacts on the status of brane inflation models. We find that, when the direct H_0 measurement is considered, the prototype model of brane inflation is still in good agreement with the current observational data within the 2σ level range. For the KKLMMT model, the consideration of the H_0 measurement allows the range of the parameter β to be amplified to O(10~(-2)), which slightly alleviates the fine-tuning problem. For the IR DBI model, the addition of the H_0 measurement does not provide a better fit. These results show that the consideration of the new H_0 prior can exert a considerable influence on the brane inflation models. At last, we show that, when β≤1.1, the equilateral non-Gaussianity in the IR DBI inflation model is compatible with the current CMB data at the 1σ level. 相似文献
12.
K. Hida 《Zeitschrift für Physik B Condensed Matter》1985,61(2):223-229
The quantum-thermal crossover in the decay rate of metastable states of the quantum sine-Gordon model in dc field is discussed at low temperatures including dissipation in arbitrary dimension. In the low field limit, the thermal effect is always dominant, whereas in the higher field the quantum effect becomes important. The crossover field becomes larger by the dissipative effect. The crossover is sharp except the one dimensional underdamped case at low temperatures. 相似文献
13.
《Physics letters. A》2020,384(28):126744
We study the influence of higher-order effects such as third order dispersion (TOD), fourth order dispersion (FOD), quintic nonlinearity (QN), self steepening (SS) and second order nonlinear dispersion (SOND) on the dynamics of dissipative soliton (DS) in metamaterials. Considering each higher-order effect as a perturbation to the system and following Lagrangian variational method, we demonstrate stable dynamics of DS as a result of the interplay between different higher-order effects. We also perform numerical analysis to confirm the analytical results. 相似文献
14.
Kinematical models are constrained by the latest observational data from geometry-distance measurements, which include 557 type Ia supernovae (SNIa) Union2 data and 15 observational Hubble data. Considering two parameterized deceleration parameter, the values of current deceleration parameter q0, jerk parameter j0 and transition redshift zT, are obtained. Furthermore, we show the departures for two parameterized kinematical models from ΛCDM model according to the evolutions of jerk parameter j(z). Also, it is shown that the constraint on jerk parameter j(z) is weak by the current geometrical observed data. 相似文献
15.
The statistical and fluctuational properties of an electromagnetic field in a nonideal cavity are studied with the help of the collective two-atom Jaynes-Cummings model taking into account losses of photons and spontaneous radiation of atoms into bath modes. For the coherent state of the field and excited initial state of atoms, the general analytical expressions for the second-order field correlation function, the second-order squeezing parameters, and the squared field amplitude are obtained by solving the master equation for the density matrix. The statistics and the degree of squeezing of the cavity field mode are studied as functions of the initial field intensity and of the coefficients of the energy dissipation of the system. It is shown that, for the two-atom dissipative model, compared to the single-atom model, the type of field statistics can be changed and the maximal degree of short-term squeezing can be increased. 相似文献
16.
We study the drag force on uniformly moving inclusions which interact linearly with dynamical free field theories commonly
used to study soft condensed matter systems. Drag forces are shown to be nonlinear functions of the inclusion velocity and
depend strongly on the field dynamics. The general results obtained can be used to explain drag forces in Ising systems and
also predict the existence of drag forces on proteins in membranes due to couplings to various physical parameters of the
membrane such as composition, phase and height fluctuations. 相似文献
17.
The process of the simultaneous absorption of three photons in a medium possessing weak one-photon absorption is analyzed.
The mode experiencing absorption is perturbed externally via a three-photon parametric process. It is shown that a steady-state,
three-component superposition state of light can exist in this system in the range where the amplitude of the state is small
(small perturbations of the system). The latter condition is due to the fact that, in this range of interactions, the field
spends significantly more time in one of three types of superposition states of light that form an ensemble of quantum trajectories
of the system than in the other two. 相似文献
18.
M. Bina G. Romero J. Casanova J. J. García-Ripoll A. Lulli E. Solano 《The European physical journal. Special topics》2012,203(1):207-216
We describe the dynamics of a qubit interacting with a bosonic mode coupled to a zero-temperature bath in the deep strong
coupling (DSC) regime. We provide an analytical solution for this open system dynamics in the off-resonance case of the qubit-mode
interaction. Collapses and revivals of parity chain populations and the oscillatory behavior of the mean photon number are
predicted. At the same time, photon number wave packets, propagating back and forth along parity chains, become incoherently
mixed. Finally, we investigate numerically the effect of detuning on the validity of the analytical solution. 相似文献
19.
20.
Xin Zhang 《中国科学:物理学 力学 天文学(英文版)》2017,60(6):060421
<正>Recently,Riess et al.[1]reported the new result of local measurement of the Hubble constant,H_0=(73.00±1.75)km s~(-1) Mpc~(-1),which is 3.3σhigher than the fit result of ocal measurement of the Hubble constant, H_0 = (73.00 ± 1.75) km s~(-1) Mpc~(-1), which is 3.3σ higher than the fit result of (66.93±0.62) km s~(-1) Mpc~(-1) derived by the Planck collaboration based on theΛCDM model withmν=0.06 e V using the latest Planck CMB data.The tension between the latest H0measurement and the Planck data has inspired numerous discussions.On one hand,it might be caused by some systematic uncertainties in the measurements.On the other hand,perhaps one has omitted some unknown physical factors in the cosmological model,which leads to some inconsistencies among different data sets.For example,replacing the cosmological constant with a dynamical dark energy[2]and considering the extra relativistic degrees of freedom(i.e.,an additional parameter Neff)[1,3,4]both can help relieve this tension to some extent.It was also shown in ref.[4]that the involvement of light sterile neutrinos in the cosmological model can simultaneously relieve almost all the tensions among the current astrophysical observations,which leads to a new cosmic concordance. 相似文献