arXiv subjects

Machiko Hatsuda

Publications and source records attributed to Machiko Hatsuda.

At least 37 records · Page 2Linked to original sources

arXiv2009

Coset for Hopf fibration and Squashing

We provide a simple derivation of metrics for fundamental geometrical deformations such as Hopf fibration, squashing and Z_k quotient which play essential roles in recent studies on the AdS4/CFT3. A general metric formula of Hopf fibrations for complex and quaternion cosets is presented. Squashing is given by a similarity transformation which changes the metric preserving the isometry symmetry of the projective space. On the other hand Z_k quotient is given as a lens space which changes the topology preserving the "local" metric.

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arXiv2009

First-quantized N=4 Yang-Mills

We present simple first-class-constraint actions and BRST operators for the 4D N=4 superparticle. Each generation of ghosts has 2 super-indices, like the coordinates. The constraints that define projective superspace close in a super Yang-Mills background due to the presence of a (non-central) U(1) generator in the algebra.

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arXiv2008

Kappa symmetric OSp(2|2) WZNW model

We construct a kappa symmetric WZNW model for the OSp(2|2) supergroup, whose bosonic part is AdS3xS1 space. The field equation gives the chiral current conservation and the right/left factorization is shown after the kappa symmetry is fixed. The right-moving modes contain both bosons and fermions while the left-moving modes contain only bosons.

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arXiv2008

Projective Coordinates and Projective Space Limit

The "projective lightcone limit" has been proposed as an alternative holographic dual of an AdS space. It is a new type of group contraction for a coset G/H preserving the isometry group G but changing H. In contrast to the usual group contraction, which changes G preserving the spacetime dimension, it reduces the dimensions of the spacetime on which G is realized. The obtained space is a projective space on which the isometry is realized as a linear fractional transformation. We generalize and apply this limiting procedure to the "Hopf reduction" and obtain (n-1)-dimensional complex projective space from (2n-1)-dimensional sphere preserving SU(n) symmetry.

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arXiv2008

Superconformal spaces and implications for superstrings

We clarify some properties of projective superspace by using a manifestly superconformal notation. In particular, we analyze the N=2 scalar multiplet in detail, including its action, and the propagator and its super-Schwinger parameters. The internal symmetry is taken to be noncompact (after Wick rotation), allowing boundary conditions that preserve it off shell. Generalization to N=4 suggests the coset superspace PSU(2,2|4)/OSp(4|4) for the AdS/CFT superstring.

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arXiv2006

Nonlocal charges of T-dual strings

We obtain sets of infinite number of conserved nonlocal charges of strings in a flat space and pp-wave backgrounds, and compare them before and after T-duality transformation. In the flat background the set of nonlocal charges is the same before and after the T-duality transformation with interchanging odd and even-order charges. In the IIB pp-wave background an infinite number of nonlocal charges are independent, contrast to that in a flat background only the zero-th and first order charges are independent. In the IIA pp-wave background, which is the T-dualized compactified IIB pp-wave background, the zero-th order charges are included as a part of the set of nonlocal charges in the IIB background. To make this correspondence complete a variable conjugate to the winding number is introduced as a Lagrange multiplier in the IIB action a la Buscher's transformation.

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arXiv2005

Classical Integrability and Super Yangian of Superstring on AdS_5 x S^5

We discuss a classical integrability in the type IIB string theory on the AdS_5 x S^5 background. By using the Roiban-Siegel formulation of the superstring on the AdS_5 x S^5, we carefully treat the Wess-Zumino term and the constraint conditions intrinsic to the supersymmetric case, and construct explicitly non-local charges for a hidden infinite-dimensional symmetry. The existence of the symmetry is shown by Bena-Polchinski-Roiban. Then the super Yangian algebra is calculated. We also show the Serre relation ensuring the structure of the Hopf algebra. In addition, the classical integrability is discussed by constructing the Lax pair and the transfer matrix.

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arXiv2005

Sugawara form for AdS superstring

We show that the stress-energy tensor for a superstring in the AdS5xS5 background is written in a supersymmetric generalized "Sugawara" form. It is the "supertrace" of the square of the right-invariant current which is the Noether current satisfying the flatness condition. The Wess-Zumino term is taken into account through the supersymmetric gauge connection in the right-invariant currents, therefore the obtained stress-energy tensor is kappa invariant. The integrability of the AdS superstring provides an infinite number of the conserved "local" currents which are supertraces of the n-th power of the right-invariant current. For even n the "local" current reduces to terms proportional to the Virasoro constraint and the kappa symmetry constraint, while for odd n it reduces to a term proportional to the kappa symmetry constraint .

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arXiv2004

Wess-Zumino terms for AdS D-branes

We show that Wess-Zumino terms for D-p branes with p>0 in the Anti-de Sitter (AdS) space are given in terms of "left-invariant" currents on the super-AdS group or the "expanded" super-AdS group. As a result there is no topological extension of the super-AdS algebra. In the flat limit the global Lorentz rotational charges of the AdS space turn out to be brane charges of the supertranslation algebra representing the BPS mass. We also show that a D-instanton is described by the GL(1) degree of freedom in the Roiban-Siegel formalism based on the GL(4|4)/[Sp(4)xGL(1)]^2 coset.

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arXiv2003

Snyderspace

We generalize the construction of Snyder to a Lorentz covariant noncommutative superspace.

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arXiv2003

Noncommutative Superspace, Supermatrix and Lowest Landau Level

By using graded (super) Lie algebras, we can construct noncommutative superspace on curved homogeneous manifolds. In this paper, we take a flat limit to obtain flat noncommutative superspace. We particularly consider $d=2$ and $d=4$ superspaces based on the graded Lie algebras $osp(1|2)$, $su(2|1)$ and $psu(2|2)$. Jacobi identities of supersymmetry algebras and associativities of star products are automatically satisfied. Covariant derivatives which commute with supersymmetry generators are obtained and chiral constraints can be imposed. We also discuss that these noncommutative superspaces can be understood as constrained systems analogous to the lowest Landau level system.

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arXiv2003

A new holographic limit of AdS5 x S5

We re-examine the projective lightcone limit of the gauge-invariant Green-Schwarz action on 5D anti-de Sitter x the five-sphere. It implies the usual holography for AdS5, but also (a complex) one for S5. The result is N=4 projective superspace, which unlike N=4 harmonic superspace can describe N=4 super Yang-Mills off shell.

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arXiv2003

AdS and pp-wave D-particle superalgebras

We derive anticommutators of supercharges with a brane charge for a D-particle in AdS(2) x S(2) and pp-wave backgrounds. A coset GL(2|2)/(GL(1))^4 and its Penrose limit are used with the supermatrix-valued coordinates for the AdS and the pp-wave spaces respectively. The brane charges have position dependence, and can be absorbed into bosonic generators by shift of momenta which results in closure of the superalgebras.

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arXiv2003

Wess-Zumino term for the AdS superstring and generalized Inonu-Wigner contraction

We examine a Wess-Zumino term, written in bilinear of superinvariant currents, for a superstring in anti-de Sitter (AdS) space. The standard Inonu-Wigner contraction does not give the correct flat limit but gives zero. This originates from the fact that the fermionic metric of the super-Poincare group is degenerate. We propose a generalization of the Inonu-Wigner contraction which reduces the super-AdS group to the "nondegenerate" super-Poincare group, therefore it gives a correct flat limit of this Wess-Zumino term. We also discuss the M-algebra obtained by this generalized Inonu-Wigner contraction from osp(1|32).

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arXiv2002

Gauge invariant action for superstring in Ramond-Ramond plane-wave background

We present a gauge invariant action for a superstring in the plane wave background with Ramond-Ramond (RR) five-form flux. The Wess-Zumino term is given explicitly in a bilinear form of the left invariant currents by introducing a fermionic center to define the nondegenerate group metric. The reparametrization invariance generators, whose combinations are conformal generators, and fermionic constraints, half of which generate kappa-symmetry, are obtained. Equations of motion are obtained in conformal invariant and background covariant manners.

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arXiv2002

Wess-Zumino term for AdS superstring

We examine a bilinear form Wess-Zumino term for a superstring in anti-de Sitter (AdS) spaces. This is composed of two parts; a bilinear term in superinvariant currents and a total derivative bilinear term which is required for the pseudo-superinvariance of the Wess-Zumino term. The covariant supercharge commutator containing a string charge is also obtained.

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arXiv2002

Super-PP-wave Algebra from Super-AdS x S Algebras in Eleven-dimensions

Maximally supersymmetric spacetime algebras in eleven-dimensions, which are the isometry superalgebras of Minkowski space, AdS_7 x S^4, AdS_4 x S^7 and pp-wave background, are related by Inonu-Wigner contractions. The super-AdS_{4(7)} x S^{7(4)} algebras allow to introduce two contraction parameters, the one for the flat limit to the super-Poincare algebra and the other for a Penrose limit to the super-pp-wave algebra. Under these contractions supersymmetries are maintained because the Jacobi identity of three supercharges holds for any values of contraction parameters.

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arXiv2002

From Super-AdS_5xS^5 Algebra to Super-pp-wave Algebra

The isometry algebras of the maximally supersymmetric solutions of IIB supergravity are derived by the Inonu-Wigner contractions of the super-AdS_5xS^5 algebra. The super-AdS_5xS^5 algebra allows introducing two contraction parameters; the one for the Penrose limit to the maximally supersymmetric pp-wave algebra and the AdS_5xS^5 radius for the flat limit. The fact that the Jacobi identity of three supercharges holds irrespectively of these parameters reflects the fact that the number of supersymmetry is not affected under both contractions.

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