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Noriaki Ogawa

Publications and source records attributed to Noriaki Ogawa.

14 recordsLinked to original sources
arXiv2017

Dynamical Pattern Selection of Growing Cellular Mosaic in Fish Retina

A Markovian lattice model for photoreceptor cells is introduced to describe the growth of mosaic patterns on fish retina. The radial stripe pattern observed in wild-type zebrafish is shown to be selected naturally during the retina growth, against the geometrically equivalent, circular stripe pattern. The mechanism of such dynamical pattern selection is clarified on the basis of both numerical simulations and theoretical analyses, which find that the successive emergence of local defects plays a critical role in the realization of the wild-type pattern.

q-bio.CB↗
arXiv2015

Holographic Entanglement and Causal Shadow in Time-Dependent Janus Black Hole

We holographically compute an inter-boundary entanglement entropy in a time-dependent two-sided black hole which was constructed in hep-th/0701108 by applying time-dependent Janus deformation to BTZ black hole. The black hole contains "causal shadow region" which is causally disconnected from both the conformal boundaries. We find that the Janus deformation results in an earlier phase transition between the extremal surfaces and that the phase transition disappears when the causal shadow is sufficiently large.

hep-th↗
arXiv2015

Holographic Heavy Quark Symmetry

We investigate the heavy quark spin symmetry, i.e. the mass degeneracy of pseudo-scalar and vector quarkonia at heavy quark limit, by using the gauge/gravity correspondence. We allow generic D3-like geometry with a flavor D7-brane, to avoid supersymmetric mass degeneracy. For geometries admitting physical QCD-like properties, we find that the mass degeneracy is generically achieved in a good accuracy, up to a few percent mass splitting. We also compute spectra of excited quarkonia states, and discuss comparisons with experiments and quark-model calculations.

hep-th↗
arXiv2014

On the Entanglement of Multiple CFTs via Rotating Black Hole Interior

We study the minimal surfaces between two of the multiple boundaries of 3d maximally extended rotating eternal black hole. Via AdS/CFT, this corresponds to investigating the behavior of entanglements of the boundary CFT with multiple sectors. Non-trivial time evolutions of such entanglements detect the geometry inside the horizon, and behave differently depending on the choice of the two boundaries.

hep-th↗
arXiv2012

Holographic Fermi Surfaces and Entanglement Entropy

We argue that Landau-Fermi liquids do not have any gravity duals in the purely classical limit. We employ the logarithmic behavior of entanglement entropy to characterize the existence of Fermi surfaces. By imposing the null energy condition, we show that the specific heat always behaves anomalously. We also present a classical gravity dual which has the expected behavior of the entanglement entropy and specific heat for non-Fermi liquids.

hep-th↗
arXiv2012

Soliton Stars as Holographic Confined Fermi Liquids

In this paper, we study a holographic dual of a confined fermi liquid state by putting a charged fluid of fermions in the AdS soliton geometry. This can be regarded as a confined analogue of electron stars. Depending on the parameters such as the mass and charge of the bulk fermion field, we found three different phase structures when we change the values of total charge density at zero temperature. In one of the three cases, our confined solution (called soliton star) is always stable and this solution approaches to the electron star away from the tip. In both the second and third case, we find a confinement/deconfinement phase transition. Moreover, in the third one, there is a strong indication that the soliton star decays into an inhomogeneous solution. We also analyze the probe fermion equations (in the WKB approximation) in the background of this soliton star geometry to confirm the presence of many fermi-surfaces in the system.

hep-th↗
arXiv2011

Higher Derivative Corrections to Holographic Entanglement Entropy for AdS Solitons

We investigate the behaviors of holographic entanglement entropy for AdS soliton geometries in the presence of higher derivative corrections. We calculate the leading higher derivative corrections for the AdS5 setup in type IIB string and for the AdS4,7 ones in M-theory. We also study the holographic entanglement entropy in Gauss-Bonnet gravity and study how the confinement/deconfinement phase transition observed in AdS solitons is affected by the higher derivative corrections.

hep-th↗
arXiv2011

Emergent AdS_3 in the Zero Entropy Extremal Black Holes

We investigate the zero entropy limit of the near horizon geometries of D=4 and D=5 general extremal black holes with SL(2,R)xU(1)^{D-3} symmetry. We derive some conditions on the geometries from expectation of regularity. We then show that an AdS_3 structure emerges in a certain scaling limit, though the periodicity shrinks to zero. We present some examples to see the above concretely. We also comment on some implications to the Kerr/CFT correspondence.

hep-th↗
arXiv2011

On Non-Chiral Extension of Kerr/CFT

We discuss possible non-chiral extension of the Kerr/CFT correspondence. We first consider the near horizon geometry of an extremal BTZ black hole and study the asymptotic symmetry. In order to define it properly, we introduce a regularization and show that the asymptotic symmetry becomes the desirable non-chiral Virasoro symmetry with the same central charges for both left and right sectors, which are independent of the regularization parameter. We then investigate the non-chiral extension for general extremal black holes in the zero entropy limit. Since the same geometric structure as above emerges in this limit, we identify non-chiral Virasoro symmetry by a similar procedure. This observation supports the existence of a hidden non-chiral CFT_2 structure with the same central charges for both left and right sectors dual to the rotating black holes.

hep-th↗
arXiv2009

The Kerr/CFT Correspondence and String Theory

The Kerr/CFT correspondence is a holographic duality between a two dimensional chiral conformal field theory (CFT) and the very near horizon limit of an extremal black hole, which includes an AdS2 structure. To understand the dual chiral CFT2, we apply the Kerr/CFT correspondence to a certain class of black holes embedded in string theory, which include the D1-D5-P and the BMPV black holes, and obtain the correct entropies for the black holes microscopically. These have an AdS3 structure in the near horizon geometry and an AdS2 structure in the very near horizon geometry. We identified one of the two Virasoro symmetries in the nonchiral CFT2 dual to the AdS3, i.e. in the AdS3/CFT2, with the Virasoro symmetry in the chiral CFT2 dual to the AdS2, i.e. in the Kerr/CFT correspondence. We also discuss a way to understand the chiral CFT2 dual to generic extremal black holes. A kind of universality for the very near horizon geometries of extremal black holes will be important for the validity of the Kerr/CFT correspondence. Based on this analysis, we propose that the Kerr/CFT correspondence can be understood as a decoupling limit in which only the ground states remain.

hep-th↗
arXiv2009

Holographic Duals of Kaluza-Klein Black Holes

We apply Brown-Henneaux's method to the 5D extremal rotating Kaluza-Klein black holes essentially following the calculation of the Kerr/CFT correspondence, which is not based on supersymmetry nor string theory. We find that there are two completely different Virasoro algebras that can be obtained as the asymptotic symmetry algebras according to appropriate boundary conditions. The microscopic entropies are calculated by using the Cardy formula for both boundary conditions and they perfectly agree with the Bekenstein-Hawking entropy. The rotating Kaluza-Klein black holes contain a 4D dyonic Reissner-Nordstrom black hole and Myers-Perry black hole. Since the D-brane configurations corresponding to these black holes are known, we expect that our analysis will shed some light on deeper understanding of chiral CFT2's dual to extremal black holes.

hep-th↗
arXiv2009

Higher-Derivative Corrections to the Asymptotic Virasoro Symmetry of 4d Extremal Black Holes

We study the asymptotic Virasoro symmetry which acts on the near-horizon region of extremal four-dimensional black hole solutions of gravity theories with higher-derivative corrections, following the recently proposed Kerr/CFT correspondence. We demonstrate that its central charge correctly reproduces the entropy formula of Iyer-Wald, once the boundary terms in the symplectic structure are carefully chosen.

hep-th↗
arXiv2008

Coarse-graining of bubbling geometries and the fuzzball conjecture

In the LLM bubbling geometries, we compute the entropies of black holes and estimate their "horizon" sizes from the fuzzball conjecture, based on coarse-graining on the gravity side. The differences of black hole microstates cannot be seen by classical observations. Conversely, by counting the possible deformations of the geometry which are not classically detectable, we can calculate the entropy. We carry out this method on the black holes of the LLM bubbling geometries, such as the superstar, and obtain the same result as was derived by coarse-graining directly on the CFT (fermion) side. Second, by application of this method, we can estimate the "horizon" sizes of those black holes, based on the fuzzball conjecture. The Bekenstein-Hawking entropy computed from this "horizon" agrees with that microscopic entropy above. This result supports the fuzzball conjecture.

hep-th↗