Search

Along with the development of the interferometric gravitational wave detector, we enter into an epoch of the gravitational wave astronomy, which will open a brand new window for astrophysics to observe our universe. However, the gravitational wave detection is a typical weak signal detection, and this weak signal is buried in a strong instrument noise. To our knowledge, almost all of the data analysis methods in gravitational wave detection at present are based on a matched filtering. So it is desirable to take advantage of stochastic resonance methods. However, the all of the stochastic resonance methods are general based on a Fourier transformation and fall short of the matched filtering as a usable technique. In this paper we relate the stochastic resonance to the matched filtering. Our results show that the stochastic resonance can indeed be combined with the matched filtering for both the periodic and the non-periodic input signal. This encouraging result will be the first step to apply the stochastic resonance to the matched filtering in gravitational wave detection. Moreover, based on the matched filtering, we firstly propose a novel measurement method for the stochastic resonance which is valid for both the periodic and the non-periodic driven signal.

We study a holographic p-wave superconductor model in a four dimensional Einstein-Maxwell-complex vector field theory with a negative cosmological constant. The complex vector field is charged under the Maxwell field. We solve the full coupled equations of motion of the system and find black hole solutions with the vector hair. The vector hairy black hole solutions are dual to a thermal state with the U(1) symmetry as well as the spatial rotational symmetry breaking spontaneously. Depending on two parameters, the mass and charge of the vector field, we find a rich phase structure: zeroth order, first order and second order phase transitions can happen in this model. We also find "retrograde condensation" in which the hairy black hole solution exists only for the temperatures above a critical value with the free energy much larger than the black hole without hair. We construct the phase diagram for this system in terms of the temperature and charge of the vector field., v3: 26 pages, 15 figures, references added, extra arguments added, to appear in JHEP

We continue to study the holographic p-wave superconductor model in the Einstein-Maxwell-complex vector field theory with a non-minimal coupling between the complex vector field and the Maxwell field. In this paper we work in the AdS soliton background which describes a conformal field theory in the confined phase and focus on the probe approximation. We find that an applied magnetic field can lead to the condensate of the vector field and the AdS soliton instability. As a result, a vortex lattice structure forms in the spatial directions perpendicular to the applied magnetic field. As a comparison, we also discuss the vector condensate in the Einstein-SU(2) Yang-Mills theory and find that in the setup of the present paper, the Einstein-Maxwell-complex vector field model is a generalization of the SU(2) model in the sense that the vector field has a general mass and gyromagnetic ratio., v2: minor changes, to appear in JHEP. arXiv admin note: text overlap with arXiv:1309.2098

We study a holographic model with vector condensate by coupling the anti-de Sitter gravity to an Abelian gauge field and a charged vector field in $(3+1)$ dimensional spacetime. In this model there exists a non-minimal coupling of the vector filed to the gauge field. We find that there is a critical temperature below which the charged vector condenses via a second order phase transition. The DC conductivity becomes infinite and the AC conductivity develops a gap in the condensed phase. We study the effect of a background magnetic field on the system. It is found that the background magnetic field can induce the condensate of the vector field even in the case without chemical potential/charge density. In the case with non-vanishing charge density, the transition temperature raises with the applied magnetic field, and the condensate of the charged vector operator forms a vortex lattice structure in the spatial directions perpendicular to the magnetic field., v3: minor changes, references added, to appear in JHEP

We study the behaviors of entanglement entropy and vacuum expectation value of Wilson loop in the St\"{u}ckelberg holographic insulator/superconductor model. This model has rich phase structures depending on model parameters. Both the entanglement entropy for a strip geometry and the heavy quark potential from the Wilson loop show that there exists a "confinement/deconfinement" phase transition. In addition, we find that the non-monotonic behavior of the entanglement entropy with respect to chemical potential is universal in this model. The pseudo potential from the spatial Wilson loop also has a similar non-monotonic behavior. It turns out that the entanglement entropy and Wilson loop are good probes to study the properties of the holographic superconductor phase transition., Comment: 23 pages,12 figures. v2: typos corrected, accepted in JHEP