Disorder effects on the quantum coherence of a many-boson system

The effects of disorders on the quantum coherence for many-bosons are studied in a double well model. For the ground state, the disorder enhances the quantum coherence. In the deep Mott regime, dynamical evolution reveals periodical collapses and revivals of the quantum coherence which is robust against the disorder. The average over variations in both the on-site energy and the interaction reveals a beat phenomenon of the coherence-decoherence oscillation in the temporal evolution.Comment: 4 figure

Top quark decays with flavor violation in the B-LSSM

The decays of top quark $t\rightarrow c\gamma,\;t\rightarrow cg,\;t\rightarrow cZ,\;t\rightarrow ch$ are extremely rare processes in the standard model (SM). The predictions on the corresponding branching ratios in the SM are too small to be detected in the future, hence any measurable signal for the processes at the LHC is a smoking gun for new physics. In the extension of minimal supersymmetric standard model with an additional local $U(1)_{B-L}$ gauge symmetry (B-LSSM), new gauge interaction and new flavor changing interaction affect the theoretical evaluations on corresponding branching ratios of those processes. In this work, we analyze those processes in the B-LSSM, under a minimal flavor violating assumption for the soft breaking terms. Considering the constraints from updated experimental data, the numerical results imply $Br(t\rightarrow c\gamma)\sim5\times10^{-7}$, $Br(t\rightarrow cg)\sim2\times10^{-6}$, $Br(t\rightarrow cZ)\sim4\times10^{-7}$ and $Br(t\rightarrow ch)\sim3\times10^{-9}$ in our chosen parameter space. Simultaneously, new gauge coupling constants $g_{_B},\;g_{_{YB}}$ in the B-LSSM can also affect the numerical results of $Br(t\rightarrow c\gamma,\;cg,\;cZ,\;ch)$.Comment: 20 pages, 4 figures, published in EPJC. arXiv admin note: substantial text overlap with arXiv:1803.0990

Active backstepping control of combined projective synchronization among different nonlinear systems

In this article, the authors have studied combination projective synchronization using active backstepping method. The main contribution of this effort is realization of the projective synchronization between two drive systems and one response system. We relax some limitations of previous work, where only combination complete synchronization has been investigated. According to Lyapunov stability theory and active backstepping design method, the corresponding controllers are designed to observe combination projective synchronization among three different classical chaotic systems, i.e. the Lorenz system, Rossler system and € Chen system. The numerical simulation examples verify the effectiveness of the theoretical analysis. Combination projective synchronization has stronger anti-attack ability and antitranslated ability than the normal projective synchronization scheme realized by one drive and one response system in secure communication

Formation of episodic jets and associated flares from black hole accretion systems

Episodic ejections of blobs (episodic jets) are widely observed in black hole sources and usually associated with flares. In this paper, by performing and analyzing three dimensional general relativity magnetohydrodynamical numerical simulations of accretion flows, we investigate their physical mechanisms. We find that magnetic reconnection occurs in the accretion flow, likely due to the turbulent motion and differential rotation of the accretion flow, resulting in flares and formation of flux ropes. Flux ropes formed inside of 10-15 gravitational radii are found to mainly stay within the accretion flow, while flux ropes formed beyond this radius are ejected outward by magnetic forces and form the episodic jets. These results confirm the basic scenario proposed in Yuan et al.(2009). Moreover, our simulations find that the predicted velocity of the ejected blobs is in good consistency with observations of Sgr A*, M81, and M87. The whole processes are found to occur quasi-periodically, with the period being the orbital time at the radius where the flux rope is formed. The predicted period of flares and ejections is consistent with those found from the light curves or image of Sgr A*, M87, and PKS 1510-089. The possible applications to protostellar accretion systems are discussed.Comment: 16 pages, 13 figures; accepted for publication in Ap

The properties of wind and jet from a super-Eddington accretion flow around a supermassive black hole

Wind and jet are important medium of AGN feedback thus it is crucial to obtain their properties for the feedback study. In this paper we investigate the properties of wind and jet launched from a super-Eddington accretion flow around a supermassive black hole. For this aim, we have performed radiation magnetohydrodynamical simulation of a magnetically arrested super-Eddington accretion flows. We then have analyzed the simulation data by the ``virtual particle trajectory'' approach and obtained the mass flux, poloidal and toroidal velocities, and mass-flux-weighted momentum and energy fluxes of wind and jet. The mass flux is found to be 2-6 times higher than that obtained based on the time-averaged streamline method widely used in literature. Depending on the black hole spin, the momentum flux of wind is found to be at least 2 times larger than that of jet, while the total energy flux of jet is at most 3 times larger than that of wind. These results are similar to the case of hot accretion flows and imply that winds likely play a more important role than jet in AGN feedback. The acceleration mechanism of wind and jet is analyzed and found to be dominated by Lorentz force rather than radiation force.Comment: 13 pages, 13 figures; submitted to MNRA