Simulation of radial expansion of an electron beam injected into a background plasma

A 2-D electrostatic particle code was used to study the beam radial expansion of a nonrelativistic electron beam injected from an isolated equipotential conductor into a background plasma. The simulations indicate that the beam radius is generally proportional to the beam electron gyroradius when the conductor is charged to a large potential. The simulations also suggest that the charge buildup at the beam stagnation point causes the beam radial expansion. From a survey of the simulation results, it is found that the ratio of the beam radius to the beam electron gyroradius increases with the square root of beam density and decreases inversely with beam injection velocity. This dependence is explained in terms of the ratio of the beam electron Debye length to the ambient electron Debye length. These results are most applicable to the SEPAC electron beam injection experiments from Spacelab 1, where high charging potential was observed

Superfluid gap formation in a fermionic optical lattice with spin imbalanced populations

We investigate the attractive Hubbard model in infinite spatial dimensions at quarter filling. By combining dynamical mean-field theory with continuous-time quantum Monte Carlo simulations in the Nambu formalism, we directly deal with the superfluid phase in the population imbalanced system. We discuss the low energy properties in the polarized superfluid state and the pseudogap behavior in the vicinity of the critical temperature.Comment: 4 pages, 1 figure, To appear in J. Phys.: Conf. Ser. for SCES201

Use of IC information in Japanese financial firms

Purpose – The purpose of this paper is to explore the perceptions of: how Japanese financial firms (JFF) acquire and use company intellectual capital (IC) information in their common routine equity investment decisions, how this activity contributes to knowledge creation in the JFFs, and how investee company knowledge creation is affected by the JFFs.<p></p> Design/methodology/approach – The research employed a multi-case design, using four JFF cases. The investigation was performed in terms of Nonaka and Toyama's “theory of the knowledge creating firm”.<p></p> Findings – IC information contributed to earnings estimates and company valuation. Emotional information contributed to JFF feelings and confidence in their information use and valuation. JFF knowledge was an important component of the key interacting and informed contexts used by JFFs. This generated opportunities to improve disclosure and accountability between JFFs and their investee companies. Common patterns of behaviour across the JFFs were counterbalanced by variety and differences noted in JFF behaviour.<p></p> Practical implications – The findings provide important insights into how JFF knowledge creating patterns could limit or progress a common language of communication between companies and markets on the subject of IC. This could impact on the quality of corporate disclosure and accountability processes.<p></p> Originality/value – The paper demonstrates that there is a need for further use of qualitative studies of financial market behavior. Especially in the area of understanding the communication of IC between firms and financial markets, the potential of using sociology of finance approaches appears to be considerable

Low temperature properties of the infinite-dimensional attractive Hubbard model

We investigate the attractive Hubbard model in infinite spatial dimensions by combining dynamical mean-field theory with a strong-coupling continuous-time quantum Monte Carlo method. By calculating the superfluid order parameter and the density of states, we discuss the stability of the superfluid state. In the intermediate coupling region above the critical temperature, the density of states exhibits a heavy fermion behavior with a quasi-particle peak in the dense system, while a dip structure appears in the dilute system. The formation of the superfluid gap is also addressed.Comment: 8 pages, 9 figure

The final fate of instability of Reissner-Nordstr\"om-anti-de Sitter black holes by charged complex scalar fields

We investigate instability of 4-dimensional Reissner-Nordstr\"om-anti-de Sitter (RN-AdS$_4$) black holes with various topologies by charged scalar field perturbations. We numerically find that the RN-AdS$_4$ black holes become unstable against the linear perturbations below a critical temperature. It is analytically shown that charge extraction from the black holes occurs during the unstable evolution. To explore the end state of the instability, we perturbatively construct static black hole solutions with the scalar hair near the critical temperature. It is numerically found that the entropy of the hairly black hole is always larger than the one of the unstable RN-AdS$_4$ black hole in the microcanonical ensemble. Our results support the speculation that the black hole with charged scalar hair always appears as the final fate of the instability of the RN-AdS$_4$ black hole.Comment: 9 pages, 4 figures. To appear in PR

Dissipation-induced pure Gaussian state

This paper provides some necessary and sufficient conditions for a generalMarkovian Gaussian master equation to have a unique pure steady state. The conditions are described by simple matrix equations; thus the so-called environment engineering problem for pure-Gaussian-state preparation can be straightforwardly dealt with in the linear algebraic framework. In fact, based on one of those conditions, for an arbitrary given pure Gaussian state,we obtain a complete parametrization of the Gaussian master equation having that state as a unique steady state; this leads to a systematic procedure for engineering a desired dissipative system.We demonstrate some examples including Gaussian cluster states.Comment: 8 page