Shunichiro Kinoshita

Non-equilibrium Condensation Process in a Holographic Superconductor

We study the non-equilibrium condensation process in a holographic superconductor. When the temperature T is smaller than a critical temperature Tc, there are two black hole solutions, the Reissner-Nordström-AdS black hole and a black hole with a scalar hair. In the boundary theory, they can be regarded as the supercooled normal phase and the superconducting phase, respectively. We consider perturbations on supercooled Reissner-Nordström-AdS black holes and study their non-linear time evolution to know about physical phenomena associated with rapidly-cooled superconductors. We find that, for T < Tc, the initial perturbations grow exponentially and, eventually, spacetimes approach the hairy black holes. We also clarify how the relaxation process from a far-from-equilibrium state proceeds in the boundary theory by observing the time dependence of the superconducting order parameter. Finally, we study the time evolution of event and apparent horizons and discuss their correspondence with the entropy of the boundary theory. Our result gives a first step toward the holographic understanding of the non-equilibrium process in superconductors.

A Holographic Dual of Bjorken Flow

We propose a consistent setup for a holographic dual of Bjorken flow of strongly coupled large-Nc N = 4 SYM-theory plasma. We employ Eddington-Finkelstein type coordinates for the dual geometry, and we propose a late-time expansion there. We construct the dual geometry order by order, and we show that the transport coefficients are determined by the regularity of the geometry. We also show that the dual geometry has an apparent horizon hence an event horizon, which covers the singularity at the origin. We prove that the dual geometry is regular at all orders under an appropriate choice of the transport coefficients. Our model is a concrete well-defined example of time-dependent AdS/CFT. Subject Index: 121, 231, 451

Constraints on wrapped Dirac–Born–Infeld inflation in a warped throat

We derive constraints on the tensor to scalar ratio and on the background charge of the warped throat for DBI inflation driven by D5- and D7-branes wrapped over cycles of the throat. It is shown that the background charge well beyond the known maximal value is required in most cases for DBI inflation to generate cosmological observables compatible with the WMAP3 data. Most of the results derived in this paper are insensitive to the details of the inflaton potential, and could be applied to generic warped throats.

Asymptotic flatness at null infinity in arbitrary dimensions

We define the asymptotic flatness and discuss asymptotic symmetry at null infinity in arbitrary dimensions using the Bondi coordinates. To define the asymptotic flatness, we solve the Einstein equations and look at the asymptotic behavior of gravitational fields. Then we show the asymptotic symmetry and the Bondi mass loss law with the well-defined definition.

Dynamical stability of six-dimensional warped flux compactification

We show the dynamical stability of a six-dimensional braneworld solution with warped flux compactification recently found by the authors. We consider linear perturbations around this background spacetime, assuming axisymmetry in the extra dimensions. The perturbations are expanded in scalar-, vector-, and tensor-type harmonics of the four-dimensional Minkoswki spacetime and we analyse each type separately. It is found that there is no unstable mode in any sector and that there are zero modes only in the tensor sector, corresponding to the four-dimensional gravitons. We also obtain the first few Kaluza–Klein modes in each sector.

Electric Field Quench in AdS/CFT

A bstractAn electric field quench, a suddenly applied electric field, can induce nontrivial dynamics in confining systems which may lead to thermalization as well as a deconfinement transition. In order to analyze this nonequilibrium transitions, we use the AdS/CFT correspondence for N=2

Dynamical meson melting in holography

\mathcal{N}=2

Turbulent meson condensation in quark deconfinement

supersymmetric QCD that has a confining meson sector. We find that the electric field quench causes the deconfinement transition even when the magnitude of the applied electric field is smaller than the critical value for the static case (which is the QCD Schwinger limit for quark-antiquark pair creation). The time dependence is crucial for this phenomenon, and the gravity dual explains it as an oscillation of a D-brane in the bulk AdS spacetime. Interestingly, the deconfinement time takes only discrete values as a function of the magnitude of the electric field. We advocate that the new deconfinement phenomenon is analogous to the exciton Mott transition.