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We show that the eight-dimensional instanton solution, which satisfies the self-duality equation $F \wedge F = *_8 F \wedge F$, realizes the static Skyrmion configuration in eight dimensions through the Atiyah-Manton construction. The relevant energy functional of the Skyrme field is obtained by the formalism developed by Sutcliffe. By comparing the Skyrmion olution associated with the extreme of the energy, with the Atiyah-Manton solution constructed by the instantons, we find that they agree with high accuracy. This is a higher-dimensional analogue of the Atiyah-Manton construction of Skyrmions in four dimensions. Our result indicates that the instanton/Skyrmion correspondence seems to be an universal property in $4k \ (k=1, 2, \ldots)$ dimensions., 23 pages, 5 figures, published version

A supersymmetric extension of the Skyrme model was obtained recently, which consists of only the Skyrme term in the Nambu-Goldstone (pion) sector complemented by the same number of quasi-Nambu-Goldstone bosons. Scherk-Schwarz dimensional reduction yields a kinetic term in three or lower dimensions and a potential term in two dimensions, preserving supersymmetry. Euclidean solitons (instantons) are constructed in the supersymmetric Skyrme model. In four dimensions, the soliton is an instanton first found by Speight. Scherk-Schwarz dimensional reduction is then performed once to get a 3-dimensional theory in which a 3d Skyrmion-instanton is found and then once more to get a 2d theory in which a 2d vortex-instanton is obtained. Although the last one is a global vortex it has finite action in contrast to conventional theory. All of them are non-BPS states breaking all supersymmetries., LaTeX: 20 pages, 3 figures; V2: typos corrected

We study T-duality chains of five-branes in heterotic supergravity where the first order $\alpha'$-corrections are present. By performing the $\alpha'$-corrected T-duality transformations of the heterotic NS5-brane solutions, we obtain the KK5-brane and the exotic $5^2_2$-brane solutions associated with the symmetric, the neutral and the gauge NS5-branes. We find that the Yang-Mills gauge field in these solutions satisfies the self-duality condition in the three- and two-dimensional transverse spaces to the brane world-volumes. The $O(2,2)$ monodromy structures of the $5^2_2$-brane solutions are investigated by the $\alpha'$-corrected generalized metric. Our analysis shows that the symmetric $5^2_2$-brane solution, which satisfies the standard embedding condition, is a T-fold and it exhibits the non-geometric nature. We also find that the neutral $5^2_2$-brane solution is a T-fold at least at $\mathcal{O} (\alpha')$. On the other hand, the gauge $5^2_2$-brane solution is not a T-fold but show unusual structures of space-time., Comment: 26 pages, 1 figure, minor text improvements

We study the world-volume effective action of an exotic five-brane, known as the M-theory 5${}^3$-brane (M5${}^3$-brane) in eleven dimensions. The supermultiplet of the world-volume theory is the $\mathcal{N} = (2, 0)$ tensor multiplet in six dimensions. The world-volume action contains three Killing vectors $\hat{k}_{\hat{I}} {}^M \ (\hat{I} =1,2,3)$ associated with the $U(1)^3$ isometry. We find the effective T-duality rule for the eleven-dimensional backgrounds that transforms the M5-brane effective action to that of the M5${}^3$-brane. We also show that our action provides the source term for the M5${}^3$-brane geometry in eleven-dimensional supergravity, Comment: 23 pages, comments and references added, version published in JHEP

Construction of a supersymmetric extension of the Skyrme term was a long-standing problem because of the auxiliary field problem; that is, the auxiliary field may propagate and cannot be eliminated, and the problem of having fourth-order time derivative terms. In this paper, we construct for the first time a supersymmetric extension of the Skyrme term in four spacetime dimensions, in the manifestly supersymmetric superfield formalism that does not suffer from the auxiliary field problem. Chiral symmetry breaking in supersymmetric theories results not only in Nambu-Goldstone (NG) bosons (pions) but also in the same number of quasi-NG bosons so that the low-energy theory is described by an SL(N,C)-valued matrix field instead of SU(N) for NG bosons. The solution of auxiliary fields is trivial on the canonical branch of the auxiliary field equation, in which case our model results in a fourth-order derivative term that is not the Skyrme term. For the case of SL(2,C), we find explicitly a nontrivial solution to the algebraic auxiliary field equations that we call a non-canonical branch, which when substituted back into the Lagrangian gives a Skyrme-like model. If we restrict to a submanifold, where quasi-NG bosons are turned off, which is tantamount to restricting the Skyrme field to SU(2), then the fourth-order derivative term reduces exactly to the standard Skyrme term. Our model is the first example of a nontrivial auxiliary field solution in a multi-component model., Comment: LaTeX: 21 pages, no figures; V2: published version (minor corrections)

We study supersymmetry of N = 4 $$ \mathcal{N}=4 $$ super Yang-Mills theory in four dimensions deformed in the Ω-background. We take the Nekrasov-Shatashvili limit of the background so that two-dimensional super Poincaré symmetry is recovered. We compute the deformed central charge of the superalgebra and study the 1/2 and 1/4 BPS states. We obtain the Ω-deformed 1/2 and 1/4 BPS dyon equations from the deformed supersymmetry transformation and the Bogomol’nyi completion of the energy.

We construct world-volume effective actions of exotic $5^2_2$-branes in type IIA and IIB string theories. The effective actions are given in fully space-time covariant forms with two Killing vectors associated with background isometries. The effective theories are governed by the six-dimensional $\mathcal{N}=(2,0)$ tensor multiplet and $\mathcal{N}=(1,1)$ vector multiplet, respectively. Performing the S-duality transformation to the $5^2_2$-brane effective action in type IIB string theory, we also work out the world-volume action of the $5^2_3$-brane. We discuss some additional issues relevant to the exotic five-branes in type I and heterotic string theories., Comment: 34 pages, 2 figures, typos corrected, figures replaced

We study the string worldsheet description of the background geometry of the exotic $5^2_2$-brane where two isometries are gauged. This is an extension of the gauged linear sigma model (GLSM) for the exotic $5^2_2$-brane with a single gauged isometry. The new GLSM with two gauged isometries has only ${\mathcal N}=(2,2)$ supersymmetry rather than ${\mathcal N}=(4,4)$ supersymmetry of the original GLSM. This is caused by a conflict between two different $SU(2)_R$ associated with the two gauge symmetries. However, if we take a certain limit, we can find the genuine string sigma model of the background geometry of the exotic $5^2_2$-brane with ${\mathcal N}=(4,4)$ supersymmetry. We also investigate the worldsheet instanton corrections to the background geometry of the exotic $5^2_2$-brane. The worldsheet instanton corrections to the string sigma model can be traced in terms of the two gauge fields in the new GLSM. This new GLSM gives rise to a different feature of the quantum corrections from the one in the GLSM with the single gauged isometry., 32 pages, accepted version in JHEP

We study the twisted N=4 super Yang-Mills theories in the Omega-background with the constant R-symmetry Wilson line gauge field. Based on the classification of topological twists of N=4 supersymmetry (the half, the Vafa-Witten and the Marcus twists), we construct the deformed off-shell supersymmetry associated with the scalar supercharges for these twists. We find that the Omega-deformed action is written in the exact form with respect to the scalar supercharges as in the undeformed case.

We study worldsheet instanton corrections to the exotic 522-brane geometry in type II string theory. The BPS vortices in the N=(4,4) gauged linear sigma model modify the geometry of the 522-brane. We find that the modification of the geometry is understood by the localization in the T-dualized winding direction.

We construct off-shell superconformal actions of hypermultiplets coupled with non-Abelian gauge multiplets in three-dimensional N = 3 and N = 4 projective superspaces. We establish the explicit embeddings of the N = 2 vector and adjoint chiral superfields, that constitute the N = 4 gauge multiplets, into the tropical multiplets. We also construct the action in the four-dimensional N = 2 projective superspace., Comment: 25 pages, typos corrected, version published in JHEP

We investigate supersymmetry breaking meta-stable vacua in N=2, SU(2)\times U(1) gauge theory with N_f=2 massless flavors perturbed by the addition of small N=1 preserving mass terms in a presence of a Fayet-Iliopoulos term. We derive the low energy effective theory by using the exact results of N=2 supersymmetric QCD and examine the effective potential. At the classical level, the theory has supersymmetric vacua on Coulomb and Higgs branches. We find that supersymmetry on the Coulomb branch is dynamically broken as a consequence of the strong dynamics of SU(2) gauge symmetry while the supersymmetric vacuum on the Higgs branch remains. We also estimate the lifetimes of the local minima on the Coulomb branch. We find that they are sufficiently long and therefore the local vacua we find are meta-stable., 24 pages, 13 figures, references added

We study deformation of N=4 super Yang-Mills theory from type IIB superstrings with D3-branes in the constant R-R background. We compute disk amplitudes with one graviphoton vertex operator and investigate the zero-slope limit of the amplitudes. We obtain the effective action deformed by the graviphoton background, which contains the one defined in non(anti)commutative N=1 superspace as special case. The bosonic part of the Lagrangian gives the Chern-Simons term coupled with the R-R potential. We study the vacuum configuration of the deformed Lagrangian and find the fuzzy sphere configuration for scalar fields.

We study open string amplitudes with the D3-branes in type IIB superstring theory compactified on C2/Z2. We introduce constant graviphoton background along the branes and calculate disk amplitudes using the NSR formalism. We take the zero slope limit and investigate the effective Lagrangian on the D3-branes deformed by the graviphoton background. We find that the deformed Lagrangian agrees with that of = 2 supersymmetric U(N) gauge theory defined in non(anti)commutative = 1 superspace by choosing appropriate graviphoton background. It is also shown that abelian gauge theory defined in = 2 harmonic superspace with specific non-singlet deformation is consistent with the deformed theory.

We investigate a five-branes interpretation of hyper-K\"{a}hler geometry with torsion (HKT). This geometry is obtained by conformal transformation of the Taub-NUT space which represents a Kaluza-Klein five-brane. This HKT would represent an NS5-brane on the Taub-NUT space. In order to explore the HKT further, we compactify one transverse direction, and study the $O(2,2;{\mathbb Z}) = SL(2,{\mathbb Z}) \times SL(2,{\mathbb Z})$ monodromy structure associated with two-torus. Performing the conjugate transformation, we obtain a new solution whose physical interpretation is a defect $(p,q)$ five-brane on the ALG space. Throughout this analysis, we understand that the HKT represents a coexistent state of two kinds of five-branes. This situation is different from composite states such as $(p,q)$ five-branes or $(p,q)$ seven-branes in type IIB theory. We also study the T-dualized system of the HKT. We again find a new solution which also indicates another defect $(p,q)$ five-brane on the ALG space., Comment: 21 pages, version published in JHEP