arXiv subjects

Yosuke Imamura

Publications and source records attributed to Yosuke Imamura.

At least 55 records · Page 3Linked to original sources

arXiv2009

Monopole operators in N=4 Chern-Simons theories and wrapped M2-branes

Monopole operators in Abelian N=4 Chern-Simons theories described by circular quiver diagrams are investigated. The magnetic charges of non-diagonal U(1) gauge symmetries form the SU(p)xSU(q) root lattice where p and q are numbers of untwisted and twisted hypermultiplets, respectively. For monopole operators corresponding to the root vectors, we propose a correspondence between the monopole operators and states of a wrapped M2-brane in the dual geometry.

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arXiv2009

N=4 Chern-Simons theories and wrapped M-branes in their gravity duals

We investigate a class of N=4 quiver Chern-Simons theories and their gravity duals. We define the group of fractional D3-brane charges in a type IIB brane setup with taking account of D3-brane creation due to Hanany-Witten effect, and confirm that it agrees with the 3-cycle homology of the dual geometry, which describes the charges of fractional M2-branes, M5-branes wrapped on 3-cycles. The relation between the fractional brane charge and the torsion of the three-form potential field is partially established. We also discuss the duality between baryonic operators in the Chern-Simons theories and M5-branes wrapped on 5-cycles in the dual geometries. The degeneracy and the conformal dimension of the operators are reproduced on the gravity side. We also comment on the relation between wrapped M2-branes and monopole operators. The baryonic operators we consider are not gauge invariant. We argue that the gauge invariance cannot be imposed on all the operators corresponding to wrapped M-branes in AdS4/CFT3 correspondence.

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arXiv2009

On the moduli space of elliptic Maxwell-Chern-Simons theories

We analyze the moduli space of the low-energy limit of 3-dimensional N=3 Maxwell-Chern-Simons theories described by circular quiver diagrams, as for 4-dimensional elliptic models. We define the theories by using D3-NS5-(k,1)5-brane systems with an arbitrary number of fivebranes. The supersymmetry is expected to be enhanced to N=4 in the low-energy limit. We show that the Higgs branch, in which all bifundamental scalar fields develop vacuum expectation values, is an abelian orbifold of C^4. We confirm that the same geometry is obtained as an M-theory dual of the brane system. We also consider theories realized by introducing more than two kinds of fivebranes, and obtain nontoric fourfolds as moduli spaces.

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arXiv2008

Quiver Chern-Simons theories and crystals

We consider N=2 quiver Chern-Simons theories described by brane tilings, whose moduli spaces are toric Calabi-Yau 4-folds. Simple prescriptions to obtain toric data of the moduli space and a corresponding brane crystal from a brane tiling are proposed.

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arXiv2008

N=4 Chern-Simons theories with auxiliary vector multiplets

We investigate a class of quiver-type Chern-Simons gauge theories with some Chern-Simons couplings vanishing. The vanishing of the couplings means that the corresponding vector fields are auxiliary fields. We show that these theories possess N=4 supersymmetry by writing down the actions and the supersymmetry transformation in terms of component fields in manifestly Spin(4) covariant form.

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arXiv2008

M2 to D2 revisited

We present two derivations of the multiple D2 action from the multiple M2-brane model proposed by Bagger-Lambert and Gustavsson. The first one is to start from Lie 3-algebra associated with given (arbitrary) Lie algebra. The Lie 3-algebra metric is not positive definite but the zero-norm generators merely correspond to Lagrange multipliers. Following the work of Mukhi and Papageorgakis, we derive D2-brane action from the model by giving a variable a vacuum expectation value. The second derivation is based on the correspondence between M2 and M5. We compactify one dimension and wind M5 brane along this direction. This leads to a noncommutative D4 action. Multiple D2 action is then obtained by suitably choosing the non-commutative parameter on the two-torus. It also implies a natural interpretation to the extra generator in Lie 3-algebra, namely the winding of M5 world volume around $S^1$ which defines the reduction of M theory to \IIA superstring.

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arXiv2008

M5-brane in three-form flux and multiple M2-branes

We investigate the Bagger-Lambert-Gustavsson model associated with the Nambu-Poisson algebra as a theory describing a single M5-brane. We argue that the model is a gauge theory associated with the volume-preserving diffeomorphism in the three-dimenisonal internal space. We derive gauge transformations, actions, supersymmetry transformations, and equations of motions in terms of six-dimensional fields. The equations of motions are written in gauge-covariant form, and the equations for tensor fields have manifest self-dual structure. We demonstrate that the double dimensional reduction of the model reproduces the non-commutative U(1) gauge theory on a D4-brane with a small non-commutativity parameter. We establish relations between parameters in the BLG model and those in M-theory. This shows that the model describes an M5-brane in a large C-field background.

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arXiv2008

Anomalies and O-plane charges in orientifolded brane tilings

We investigate orientifold of brane tilings. We clarify how the cancellations of gauge anomaly and Witten's anomaly are guaranteed by the conservation of the D5-brane charge. We also discuss the relation between brane tilings and the dual Calabi-Yau cones realized as the moduli spaces of gauge theories. Two types of flavor D5-branes in brane tilings and corresponding superpotentials of fundamental quark fields are proposed, and it is shown that the massless loci of these quarks in the moduli space correctly reproduce the worldvolume of flavor D7-branes in the Calabi-Yau cone dual to the fivebrane system.

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arXiv2007

Exactly marginal deformations of quiver gauge theories as seen from brane tilings

We study the relation between exactly marginal deformations in a large class of N=1 superconformal quiver gauge theories described by brane tilings and the degrees of freedom in the corresponding 5-brane systems. We show, with the help of NSVZ exact beta functions, that there are generically d-1 complex exactly marginal deformations of a gauge theory, where d is the perimeter of the corresponding n it, and the other two, the diagonal gauge coupling and a beta-like deformation, as background supergravity fields.toric diagram. We identify d-3 complex marginal deformations as deformations of the brane system and the Wilson lines on it, and the other two, the diagonal gauge coupling and a beta-like deformation, as background supergravity fields.

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arXiv2006

Global symmetries and 't Hooft anomalies in brane tilings

We investigate the relation between gauge theories and brane configurations described by brane tilings. We identify U(1)_B (baryonic), U(1)_M (mesonic), and U(1)_R global symmetries in gauge theories with gauge symmetries in the brane configurations. We also show that U(1)_MU(1)_B^2 and U(1)_RU(1)_B^2 't Hooft anomalies are reproduced as gauge transformations of the classical brane action.

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arXiv2006

Anomaly Cancellations in Brane Tilings

We re-interpret the anomaly cancellation conditions for the gauge symmetries and the baryonic flavor symmetries in quiver gauge theories realized by the brane tilings from the viewpoint of flux conservation on branes.

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arXiv2006

Boundary states in the open string channel and CFT near a corner

We generalize the idea of boundary states to the open string channel. They describe emission and absorption of open strings in the presence of intersecting D-branes. We construct the explicit oscillator representation for the free boson and fermionic ghost. The inner product of such states describes a disk amplitude of rectangular shape and possesses modular covariance with a nontrivial conformal weight. We compare the result obtained here with those obtained using two different methods, one employing the path integral formalism and one employing the conformal anomaly. We find that all these methods give consistent results. In our method, we must be careful in our treatment of the singularity of the CFT near the corners. Specifically, we derive the correction to the conformal weight of the primary field inserted at the corner, and it gives the modular weight of the rectangle amplitude. We also carry out explicit computations of the correlation functions.

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arXiv2006

Large N vector quantum mechanics and bubbling supertube solutions

We propose a large N vector quantum mechanics as the theory describing a D-particle probe in bubbling supertube solutions. We compute the effective action of this quantum mechanics and show that it coincides with the D-particle action in a certain decoupling limit, up to quadratic order in the velocity. The angular momentum of the D-particle, including the contribution of the Poynting vector, is reproduced as the vacuum expectation value of the SU(2)_R current.

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arXiv2006

Baryon vertices in AdS black hole backgrounds

We numerically computed the energy of QCD string junctions in non-supersymmetric SU(N) gauge theories as the energy of brane configurations in the background of AdS black hole solutions, and extracted the contribution of baryon vertices. We obtain a negative vertex energy for the three- and four-dimensional Yang-Mills theories and a vanishing vertex energy for the five-dimensional theory.

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arXiv2004

Ricci-flat deformation of orbifolds and localized tachyonic modes

We study Ricci-flat deformations of orbifolds in type II theory. We obtain a simple formula for mass corrections to the twisted modes due to the deformations, and apply it to originally tachyonic and massless states in several examples. In the case of supersymmetric orbifolds, we find that tachyonic states appear when the deformation breaks all the supersymmetries. We also study nonsupersymmetric orbifolds C^2/Z_{2N(2N+1)}, which is T-dual to N type 0 NS5-branes. For N>=2, we compute mass corrections for states, which have string scale tachyonic masses. We find that the corrected masses coincide to ones obtained by solving the wave equation for the tachyon field in the smeared type 0 NS5-brane background geometry. For N=1, we show that the unstable mode representing the bubble creation is the unique tachyonic mode.

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arXiv2004

On String Junctions in Supersymmetric Gauge Theories

We study junctions consisting of confining strings in N=1 supersymmetric large N gauge theories by means of the gauge/gravity correspondence. We realize these junctions as D-brane configurations in infrared geometries of the Klebanov-Strassler (KS) and the Maldacena-Nunez (MN) solutions. After discussing kinematics associated with the balance of tensions, we compute the energies of baryon vertices numerically. In the KS background, baryon vertices give negative contributions to the energies. The results for the MN background strongly suggest that the energies of baryon vertices exactly vanish, as in the case of supersymmetric (p,q)-string junctions. We find that brane configurations in the MN background have a property similar to the holomorphy of the M-theory realization of (p,q)-string junctions. With the help of this property, we analytically prove the vanishing of the energies of baryon vertices in the MN background.

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arXiv2003

Decay of type 0 NS5-branes to nothing

The perturbative vacuum of type 0 string theory is unstable due to the existence of the closed string tachyon. This instability can be removed by S^1 compactification with twisted boundary condition for the tachyon field. We show that even in this situation unwrapped NS5-branes are unstable and decay to bubbles of nothing smoothly without tunneling any potential barrier. We discuss a relation between the closed string tachyon condensation and the instability of NS5-branes.

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arXiv2003

Strings in a PP-wave background compactified on T^8 with twisted S^1

We study a torus-like compactification of type IIB maximally supersymmetric PP-wave background. As the most general case, we discuss a T^8 compactification of all the transverse directions. A nontrivial structure of the isometry group requires an additional light-like compactification. This additional S^1 fiber is twisted on the T^8. We determine the spectrum of closed strings in this twisted torus background and compute the thermal partition function.

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