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Masashi Naganuma

Publications and source records attributed to Masashi Naganuma.

13 recordsLinked to original sources
arXiv2004

BPS Wall Solutions in Five Dimensional Supergravity

We find an exact solution of BPS wall in five-dimensional supergravity using a gravitational deformation of the massive Eguchi-Hanson nonlinear sigma model. The warp factor decreases for both infinities of the extra dimension. Our solution requires no fine-tuning between boundary and bulk cosmological constants, in contrast to the Randall-Sundrum model. Wall solutions are also obtained with warp factors which are flat or increasing in one side by varying a deformation parameter.

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arXiv2003

BPS Multi-Walls in Five-Dimensional Supergravity

Exact BPS solutions of multi-walls are obtained in five-dimensional supergravity. The solutions contain 2n parameters similarly to the moduli space of the corresponding global SUSY models and have a smooth limit of vanishing gravitational coupling. The models are constructed as gravitational deformations of massive T^*CP^n nonlinear sigma models by using the off-shell formulation of supergravity and massive quaternionic quotient method with U(1)*U(1) gauging. We show that the warp factor can have at most single stationary point in this case. We also obtain BPS multi-wall solutions even for models which reduce to generalizations of massive T^*CP^n models with only U(1)^n isometry in the limit of vanishing gravitational coupling. At particular values of parameters, isometry of the quaternionic manifolds is enhanced.

hep-th↗
arXiv2003

An exact BPS wall solution in Five Dimensional Supergravity

In five-dimensional supergravity, an exact solution of BPS wall is found for a gravitational deformation of the massive Eguchi-Hanson nonlinear sigma model. The warp factor decreases for both infinities of the extra dimension. Thin wall limit gives the Randall-Sundrum model without fine-tuning of input parameters. We also obtain wall solutions with warp factors which are flat or increasing in one side, by varying a deformation parameter of the potential.

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arXiv2003

BPS Wall in N=2 SUSY Nonlinear Sigma Model with Eguchi-Hanson Manifold

BPS wall solutions are obtained for N=2 supersymmetric nonlinear sigma model with Eguchi-Hanson target manifold in a manifestly supersymmetric manner. The model is constructed by a massive hyper-Kahler quotient method both in the N=1 superfield and in the N=2 superfield (harmonic superspace). We describe the model in simple terms and give relations between various parameterizations which are useful to describe the model and the solution. Some more details can be found in our previous paper [hep-th/0211103]. This article is dedicated to Professor Hiroshi Ezawa on the occasion of his seventieth birthday.

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arXiv2003

Wall Solution with Weak Gravity Limit in Five Dimensional Supergravity

In five-dimensional supergravity, an exact solution of BPS wall is found for a gravitational deformation of the massive Eguchi-Hanson nonlinear sigma model. The warp factor decreases for both infinities of the extra dimension. Thin wall limit gives the Randall-Sundrum model without fine-tuning of input parameters. We also obtain wall solutions with warp factors which are flat or increasing in one side, by varying a deformation parameter of the potential.

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arXiv2003

Manifest Supersymmetry for BPS Walls in N=2 Nonlinear Sigma Models

BPS equations and wall solutions are studied keeping (part of) supersymmetry (SUSY) manifest. Using N=1 superfields, massive hyper-Kahler quotient is introduced to obtain massive N=2 (8 SUSY) nonlinear sigma models in four dimensions with T*CP(n) target manifold, which yield BPS wall solutions for the n=1 case. We also describe massive hyper-Kahler quotient of T*CP(n) by using the harmonic superspace formalism which preserves all SUSY manifestly, and BPS equations and wall solutions are obtained in the n=1 case.

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arXiv2002

BPS Walls and Junctions in ${\cal N}=1$ SUSY Nonlinear Sigma Models

The ${\cal N}=1$ SUSY nonlinear sigma models in four spacetime dimensions are studied to obtain BPS walls and junctions. A nonlinear sigma model with a single chiral scalar superfield is found which has a moduli space of the topology of $S^1$ and admits BPS walls and junctions connecting arbitrary points in moduli space. New BPS junction solutions connecting $N$ discrete vacua are also found for nonlinear sigma models with several chiral scalar superfields. More detailed exposition of our results can be found in Ref.\cite{NNS}.

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arXiv2001

BPS Lumps and Their Intersections in ${\cal N}=2$ SUSY Nonlinear Sigma Models

BPS lumps in ${\cal N}=2$ SUSY nonlinear sigma models on hyper-\kahler manifolds in four dimensions are studied. We present new lump solutions with various kinds of topological charges. New BPS equations and a new BPS bound, expressed by the three complex structures on hyper-\kahler manifolds, are found. We show that any states satisfying these BPS equations preserve 1/8 (1/4) SUSY of ${\cal N}=2$ SUSY nonlinear sigma models with (without) a potential term. These BPS states include non-parallel multi-(Q-)lumps.

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arXiv2001

BPS Walls and Junctions in SUSY Nonlinear Sigma Models

BPS walls and junctions are studied in ${\cal N}=1$ SUSY nonlinear sigma models in four spacetime dimensions. New BPS junction solutions connecting N discrete vacua are found for nonlinear sigma models with several chiral scalar superfields. A nonlinear sigma model with a single chiral scalar superfield is also found which has a moduli space of the topology of $S^1$ and admits BPS walls and junctions connecting arbitrary points in moduli space. SUSY condition in nonlinear sigma models are classified either as stationary points of superpotential or singularities of the Kähler metric in field space. The total number of SUSY vacua is invariant under holomorphic field redefinitions if we count ``runaway vacua'' also.

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arXiv2001

BPS Domain Walls in Models with Flat Directions

We consider BPS domain walls in the four dimensional N=1 supersymmetric models with continuous global symmetry. Since the BPS equation is covariant under the global transformation, the solutions of the BPS walls also have the global symmetry. The moduli space of the supersymmetric vacua in such models have non-compact flat directions, and the complex BPS walls interpolating between two disjoint flat directions can exist. We examine this possibility in two models with global O(2) symmetry, and construct the solution of such BPS walls.

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arXiv2000

An Exact Solution of BPS Junctions and Its Properties

We have obtained an exact solution for the BPS domain wall junction for a N=1 supersymmetric theory in four dimensions and studied its properties. The model is a simplified version of the N=2 SU(2) gauge theory with N_f=1 broken to N=1 by the mass of the adjoint chiral superfield. We define mode equations and demonstrate explicitly that fermion and boson with the same mass have to come in pairs except massless modes. We work out explicitly massless Nambu-Goldstone (NG) modes on the BPS domain wall junction. We find that their wave functions extend along the wall to infinity (not localized) and are not normalizable. It is argued that this feature is a generic phenomenon of NG modes on domain wall junctions in the bulk flat space in any dimensions. NG fermions exhibit a chiral structure in accordance with unitary representations of (1, 0) supersymmetry algebra where fermion and boson with the same mass come in pairs except massless modes which can appear singly.

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arXiv2000

Nonnormalizable Zero Modes on BPS Junctions

Using an exact solution as a concrete example, Nambu-Goldstone modes on the BPS domain wall junction are worked out for N=1 supersymmetric theories in four dimensions. Their wave functions extend along the wall to infinity (not localized) and are not normalizable. It is argued that this feature is a generic phenomenon of Nambu-Goldstone modes on domain wall junctions in the bulk flat space in any dimensions. We formulate mode equations and show that fermion and boson with the same mass come in pairs except massless modes which can appear singly, in accordance with unitary representations of (1, 0) supersymmetry.

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arXiv1999

An Exact Solution of BPS Domain Wall Junction

An exact solution of domain wall junction is obtained in a four-dimensional N=1 supersymmetric U(1) X U(1)' gauge theory with three pairs of chiral superfields which is motivated by the N=2 SU(2) gauge theory with one flavor perturbed by an adjoint scalar mass. The solution allows us to evaluate various quantities including a new central charge Y_k associated with the junction besides Z_k which appears already in domain walls. We find that the new central charge Y_k gives a negative contribution to the mass of the domain wall junction whereas the central charge Z_k gives a dominant positive contribution. One has to be cautious to identify the central charge Y_k alone as the mass of the junction.

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