Publications (29)155.88 Total impact

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ABSTRACT: We use localization techniques to calculate the Euclidean partition functions for $\mathcal{N}=1$ theories on fourdimensional manifolds $M$ of the form $S^1 \times M_3$, where $M_3$ is a circle bundle over a Riemann surface. These are generalizations of the $\mathcal{N}=1$ indices in fourdimensions including the lens space index. We show that these generalized indices are holomorphic functions of the complex structure moduli on $M$. We exhibit the deformation by background flat connections and the insertion of supersymmetric Wilson loops. 
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ABSTRACT: Supersymmetric Renyi entropies are defined for threedimensional N=2 superconformal field theories on a branched covering of a threesphere by using the localized partition functions. Under a conformal transformation, the branched covering is mapped to S^1 x H^2, whose gravity dual is the charged topological AdS4 black hole. The black hole can be embedded into fourdimensional N=2 gauged supergravity where the mass and charge are related so that it preserves half of the supersymmetries. We compute the supersymmetric Renyi entropies with and without a certain type of Wilson loop operators in the gravity theory. We find they agree with those of the dual field theories in the largeN limit.Journal of High Energy Physics 01/2014; 2014(7). DOI:10.1007/JHEP07(2014)061 · 6.22 Impact Factor 
Article: Supersymmetric Renyi Entropy
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ABSTRACT: We consider 3d N>= 2 superconformal field theories on a branched covering of a threesphere. The Renyi entropy of a CFT is given by the partition function on this space, but conical singularities break the supersymmetry preserved in the bulk. We turn on a compensating Rsymmetry gauge field and compute the partition function using localization. We define a supersymmetric observable, called the super Renyi entropy, parametrized by a real number q. We show that the super Renyi entropy is duality invariant and reduces to entanglement entropy in the q > 1 limit. We provide some examples.Journal of High Energy Physics 06/2013; 2013(10). DOI:10.1007/JHEP10(2013)155 · 6.22 Impact Factor 
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ABSTRACT: The coefficient tau_{RR} of the twopoint function of the superconformal U(1)_R currents of N=2 SCFTs in threedimensions is recently shown to be obtained by differentiating the partition function on a squashed threesphere with respect to the squashing parameter. With this method, we compute the tau_{RR} for N=2 WessZumino models and SQCD numerically for small number of flavors and analytically in the large number limit. We study the behavior of tau_{RR} under an RG flow by adding superpotentials to the theories. While the tau_{RR} decreases for the gauge theories, we find an N=2 WessZumino model whose tau_{RR} increases along the RG flow. Since tau_{RR} is proportional to the coefficient C_T of the twopoint correlation function of the stressenergy tensors for N=2 superconformal field theories, this rules out the possibility of C_T being a measure of the degrees of freedom which monotonically decreases along RG flows in threedimensions.Journal of High Energy Physics 03/2013; 2013(5). DOI:10.1007/JHEP05(2013)165 · 6.22 Impact Factor 
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ABSTRACT: The Renyi entropies of a massless Dirac fermion on a circle with chemical potential are calculated analytically at nonzero temperature by using the bosonization method. The bosonization of a massive Dirac fermion to the sineGordon model lets us obtain the small mass corrections to the entropies. We numerically compute the Renyi entropies by putting a massive fermion on the lattice and find agreement between the analytic and numerical results. In the presence of a mass gap, we show that corrections to Renyi and entanglement entropies in the limit m >> T scale as exp(m/T). We also show that when there is ground state degeneracy in the gapless case, the limits m to zero and T to zero do not commute.Journal of High Energy Physics 01/2013; 2013(3). DOI:10.1007/JHEP03(2013)077 · 6.22 Impact Factor 
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ABSTRACT: We study quantum quench in a holographic model of a zero temperature insulatorsuperfluid transition. The model is a modification of that of arXiv:0911.0962 and involves a selfcoupled complex scalar field, Einstein gravity with a negative cosmological constant, and Maxwell field with one of the spatial directions compact. In a suitable regime of parameters, the scalar field can be treated as a probe field whose backreaction to both the metric and the gauge field can be ignored. We show that when the chemical potential of the dual field theory lies between two critical values, the equilibrium background geometry is a AdS soliton with a constant gauge field, while the complex scalar condenses leading to broken symmetry. We then turn on a time dependent source for the order parameter which interpolates between constant values and crosses the orderdisorder critical point. In the critical region adiabaticity breaks down, but for a small rate of change of the source $v$ there is a new small$v$ expansion in fractional powers of $v$. The resulting critical dynamics is dominated by a zero mode of the bulk field. To lowest order in this small$v$ expansion, the order parameter satisfies a time dependent LandauGinsburg equation which has $z=2$, but nondissipative. These predictions are verified by explicit numerical solutions of the bulk equations of motion.Journal of High Energy Physics 11/2012; 2013(3). DOI:10.1007/JHEP03(2013)146 · 6.22 Impact Factor 
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ABSTRACT: We compute the 4d superconformal index for N=1, 2 gauge theories on S1×L(p,1), where L(p,1) is a lens space. We find that the 4d N=1, 2 index on S1×L(p,1) reduces to a 3d N=2, 4 index on S1×S2 in the large p limit, and to a 3d partition function on a squashed L(p,1) when the size of the temporal S1 shrinks to zero. As an application of our index, we study 4d N=2 superconformal field theories arising from the 6d N=(2,0) A1 theory on a punctured Riemann surface Σ, and conjecture the existence of a 2d topological quantum field theory on Σ whose correlation function coincides with the 4d N=2 index on S1×L(p,1).Physical review D: Particles and fields 09/2012; 86(6). DOI:10.1103/PhysRevD.86.065015 · 4.86 Impact Factor 
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ABSTRACT: The renormalized entanglement entropy (REE) across a circle of radius R has been proposed as a cfunction in Poincar\'e invariant (2+1)dimensional field theory. A proof has been presented of its monotonic behavior as a function of R, based on the strong subadditivity of entanglement entropy. However, this proof does not directly establish stationarity of REE at conformal fixed points of the renormalization group. In this note we study the REE for the free massive scalar field theory near the UV fixed point described by a massless scalar. Our numerical calculation indicates that the REE is not stationary at the UV fixed point.Journal of High Energy Physics 07/2012; 2012(10). DOI:10.1007/JHEP10(2012)058 · 6.22 Impact Factor 
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ABSTRACT: We use a mix of field theoretic and holographic techniques to elucidate various properties of quantum entanglement entropy. In (3+1)dimensional conformal field theory we study the divergent terms in the entropy when the entangling surface has a conical or a wedge singularity. In (2+1)dimensional field theory with a mass gap we calculate, for an arbitrary smooth entanglement contour, the expansion of the entropy in inverse odd powers of the mass. We show that the shapedependent coefficients that arise are even powers of the extrinsic curvature and its derivatives. A useful dual construction of a (2+1)dimensional theory, which allows us to exhibit these properties, is provided by the CGLP background. This smooth warped throat solution of 11dimensional supergravity describes renormalization group flow from a conformal field theory in the UV to a gapped one in the IR. For this flow we calculate the recently introduced renormalized entanglement entropy and confirm that it is a monotonic function.Journal of High Energy Physics 04/2012; 2012(7). DOI:10.1007/JHEP07(2012)001 · 6.22 Impact Factor 
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ABSTRACT: We consider N = 3 supersymmetric ChernSimons gauge theories with product unitary and orthosymplectic groups and bifundamental and fundamental fields. We study the partition functions on an S^3 by using the KapustinWillettYaakov matrix model. The saddlepoint equations in a large N limit lead to a constraint that the long range forces between the eigenvalues must cancel; the resulting quiver theories are of affine Dynkin type. We introduce a folding/unfolding trick which lets us, at the level of the large N matrix model, (i) map quivers with orthosymplectic groups to those with unitary groups, and (ii) obtain nonsimply laced quivers from the corresponding simply laced quivers using a Z_2 outer automorphism. The brane configurations of the quivers are described in string theory and the folding/unfolding is interpreted as the addition/subtraction of orientifold and orbifold planes. We also relate the U(N) quiver theories to the affine ADE quiver matrix models with a StieltjesWigert type potential, and derive the generalized Seiberg duality in 2 + 1 dimensions from Seiberg duality in 3 + 1 dimensions.Journal of High Energy Physics 01/2012; 2012(4). DOI:10.1007/JHEP04(2012)138 · 6.22 Impact Factor 
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ABSTRACT: We propose that N M5branes, put on R4/Zm with deformation parameters ϵ1,2, realize twodimensional theory with SÛ(m)N symmetry and mth paraWN symmetry. This includes the standard WN symmetry for m=1 and superViraroro symmetry for m=N=2. We provide a small check of this proposal by calculating the central charge of the 2D theory from the anomaly polynomial of the 6D theory.Physical review D: Particles and fields 08/2011; 84(4). DOI:10.1103/PhysRevD.84.046009 · 4.86 Impact Factor 
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ABSTRACT: For (3+1)dimensional fermions, a net axial charge and external magnetic field can lead to a current parallel to the magnetic field. This is the chiral magnetic effect. We use gaugegravity duality to study the chiral magnetic effect in largeNc, stronglycoupled N=4 supersymmetric SU(Nc) YangMills theory coupled to a number Nf << Nc of N=2 hypermultiplets in the Nc representation of SU(Nc), i.e. flavor fields. Specifically, we introduce an external magnetic field and a timedependent phase for the mass of the flavor fields, which is equivalent to an axial chemical potential for the flavor fermions, and we compute holographically the resulting chiral magnetic current. For massless flavors we find that the current takes the value determined by the axial anomaly. For massive flavors the current appears only in the presence of a condensate of pseudoscalar mesons, and has a smaller value than for massless flavors, dropping to zero for sufficiently large mass or magnetic field. The axial symmetry in our system is part of the Rsymmetry, and the states we study involve a net flow of axial charge to the adjoint sector from an external source coupled to the flavors. We compute the time rate of change of axial charge and of energy both in field theory and from holography, with perfect agreement. In contrast to previous holographic models of the chiral magnetic effect, in our system the vector current is conserved and gaugeinvariant without any special counterterms.Journal of High Energy Physics 06/2011; 10(10). DOI:10.1007/JHEP10(2011)084 · 6.22 Impact Factor 
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ABSTRACT: We compute the partition function on S^3 of 3d N=4 theories which arise as the lowenergy limit of 4d N=4 super YangMills theory on a segment or on a junction, and propose its 1d interpretation. We show that the partition function can be written as an overlap of wavefunctions determined by the boundary conditions. We also comment on the connection of our results with the 4d superconformal index and the 2d qdeformed YangMills theory.Journal of High Energy Physics 05/2011; 2011(8). DOI:10.1007/JHEP08(2011)003 · 6.22 Impact Factor 
Article: Lifshitzlike Janus Solutions
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ABSTRACT: We construct Lifshitzlike Janus solutions in the Einsteinscalar theory with cosmological constant in arbitrary dimensions. They are holographically dual to z=2 Lifshitzlike field theories with a defect. The fourdimensional solutions can be embedded into type IIB supergravity as dilatonic deformations of AdS_5 x Y^5 with threeform field strengths, where Y^5 is a fivedimensional Einstein manifold.Journal of High Energy Physics 10/2010; 2011(2). DOI:10.1007/JHEP02(2011)023 · 6.22 Impact Factor 
Article: New Near Horizon Limit in Kerr/CFT
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ABSTRACT: The extremal Kerr black hole with the angular momentum J is conjectured to be dual to CFT with central charges c_L=c_R=12J. However, the central charge in the right sector remains to be explicitly derived so far. In order to investigate this issue, we introduce new near horizon limits of (near) extremal Kerr and fivedimensional MyersPerry black holes. We obtain Virasoro algebras as asymptotic symmetries and calculate the central charges associated with them. One of them is equivalent to that of the previous studies, and the other is nonzero, but still the order of near extremal parameter. Redefining the algebras to take the standard form, we obtain a finite value as expected by the Kerr/CFT correspondence.Journal of High Energy Physics 10/2010; 2010(12). DOI:10.1007/JHEP12(2010)073 · 6.22 Impact Factor 
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ABSTRACT: We present holographic descriptions of thermalization in conformal field theories using probe Dbranes in AdS X S spacetimes. We find that the induced metrics on Dpbrane worldvolumes which are rotating in an internal sphere direction have horizons with characteristic Hawking temperatures even if there is no black hole in the bulk AdS. The AdS/CFT correspondence applied to such systems indeed reveals thermal properties such as Brownian motions and AC conductivities in the dual conformal field theories. We also use this framework to holographically analyze timedependent systems undergoing a quantum quench, where parameters in quantum field theories, such as a mass or a coupling constant, are suddenly changed. We confirm that this leads to thermal behavior by demonstrating the formation of apparent horizons in the induced metric after a certain time. Comment: LaTeX, 47 pages, 14 figures; Typos corrected and references added (v2); minor corrections, references added(v3)Journal of High Energy Physics 05/2010; 2010(7). DOI:10.1007/JHEP07(2010)071 · 6.22 Impact Factor 
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ABSTRACT: We analyze the fivedimensional AdS gravity coupled to a gauge field and a charged scalar field. Under a ScherkSchwarz compactification, we show that the system undergoes a superconductor/insulator transition at zero temperature in 2+1 dimensions as we change the chemical potential. By taking into account a confinement/deconfinement transition, the phase diagram turns out to have a rich structure. We will observe that it has a similarity with the RVB (resonating valence bond) approach to highTc superconductors via an emergent gauge symmetry. Comment: 25 pages, 23 figures; A new subsection on a concrete string theory embedding added, references added (v2); Typos corrected, references added (v3)Journal of High Energy Physics 11/2009; 2010(3). DOI:10.1007/JHEP03(2010)131 · 6.22 Impact Factor 
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ABSTRACT: We study possibilities of string theory embeddings of the gravity duals for nonrelativistic Lifshitzlike theories with anisotropic scale invariance. We search classical solutions in type IIA and elevendimensional supergravities which are expected to be dual to (2+1)dimensional Lifshitzlike theories. Under reasonable ansaetze, we prove that such gravity duals in the supergravities are not possible. We also discuss a possible physical reason behind this. Comment: 18 pages, Latex, flux conditions clarified (v2), brief summary of results added (v3)Journal of High Energy Physics 08/2009; DOI:10.1088/11266708/2009/10/015 · 6.22 Impact Factor 
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ABSTRACT: In this article, we review recent progresses on the holographic understandings of the entanglement entropy in the AdS/CFT correspondence. After reviewing the general idea of holographic entanglement entropy, we will explain its applications to confinement/deconfinement phase transitions, black hole entropy and covariant formulation of holography. Comment: 52 pages, Invited review article for a special issue "Entanglement entropy in extended quantum systems" in Journal of Physics A, edited by P.Calabrese, J. Cardy and B. Doyon; (v2) references addedJournal of Physics A Mathematical and Theoretical 05/2009; 42(50). DOI:10.1088/17518113/42/50/504008 · 1.69 Impact Factor 
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ABSTRACT: We consider a black hole solution whose spatial boundary is a squashed three sphere in Einstein gravity with negative cosmological constant. We solve the Einstein equations numerically and find a warped AdS black hole solution with arbitrary squashing parameter. This solution becomes the ordinary AdSSchwarzschild solution when the squashing parameter is chosen appropriately. Motivated by this fact, we study N=4 super YangMills theory with zero coupling constant on a squashed three sphere and show that the thermodynamical entropy of this theory roughly agrees with that of the warped AdS black hole up to a factor of 3/4. We also study the confinement/deconfinement transition of the gauge theory. We evaluate the approximate HawkingPage transition temperature of the warped AdS black hole and find a qualitative agreement between the transition temperatures of the gravity and the gauge theory. These results suggest a duality between the warped AdS solution and N=4 super YangMills theory on a squashed three sphere.Progress of Theoretical Physics 05/2009; 121(5):941957. DOI:10.1143/PTP.121.941 · 2.06 Impact Factor
Publication Stats
1k  Citations  
155.88  Total Impact Points  
Top Journals
Institutions

2010–2013

Princeton University
 Department of Physics
Princeton, New Jersey, United States 
The University of Tokyo
 Department of Physics
Edo, Tōkyō, Japan


2007–2009

Kyoto University
 Department of Physics II
Kyoto, Kyotofu, Japan
