arXiv subjects

S. Krivonos

Publications and source records attributed to S. Krivonos.

At least 55 records · Page 3Linked to original sources

arXiv2004

Goldstone Superfield Actions in AdS5 backgrounds

Nonlinear realizations superfield techniques, pertinent to the description of partial breaking of global N=2 supersymmetry in a flat d=4 super Minkowski background, are generalized to the case of partially broken N=1 AdS5 supersymmetry SU(2,2|1). We present, in an explicit form, off-shell manifestly N=1, d=4 supersymmetric minimal Goldstone superfield actions for two patterns of partial breaking of SU(2,2|1) supersymmetry. They correspond to two different nonlinear realizations of the latter, in the supercosets with the AdS5 and AdS5\times S1 bosonic parts. The relevant worldvolume Goldstone supermultiplets are accommodated, respectively, by improved tensor and chiral N=1, d=4 superfields. The second action is obtained from the first one by dualizing the improved tensor Goldstone multiplet into a chiral Goldstone one. In the bosonic sectors, the first and second actions yield static-gauge Nambu-Goto actions for a L3-brane on AdS5 and a scalar 3-brane on AdS5\times S1.

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arXiv2004

N=8 superconformal mechanics

We construct new models of N=8 superconformal mechanics associated with the off-shell N=8, d=1 supermultiplets (3,8,5) and (5,8,3). These two multiplets are derived as N=8 Goldstone superfields and correspond to nonlinear realizations of the N=8, d=1 superconformal group OSp(4^*|4) in its supercosets OSp(4^*|4)/U(1)_R x SO(5) and OSp(4^*|4)/SU(2)_R x SO(4), respectively. The irreducibility constraints for these superfields automatically follow from appropriate superconformal covariant conditions on the Cartan superforms. The N=8 superconformal transformations of the superspace coordinates and the Goldstone superfields are explicitly given. Interestingly, each N=8 supermultiplet admits two different off-shell N=4 decompositions, with different N=4 superconformal subgroups SU(1,1|2) and OSp(4^*|2) of OSp(4^*|4) being manifest as superconformal symmetries of the corresponding N=4, d=1 superspaces. We present the actions for all such N=4 splittings of the N=8 multiplets considered.

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arXiv2003

Goldstone Superfield Actions for Partially Broken AdS5 Supersymmetry

We explicitly construct N=1 worldvolume supersymmetric minimal off-shell Goldstone superfield actions for two options of 1/2 partial spontaneous breaking of AdS5 supersymmetry SU(2,2|1) corresponding to its nonlinear realizations in the supercosets with the AdS5 and AdS5 X S1 bosonic parts. The relevant Goldstone supermultiplets are comprised, respectively, by improved tensor and chiral N=1 superfields. The second action is obtained from the first one by duality transformation. In the bosonic sectors they yield static-gauge Nambu-Goto actions for L3-brane on AdS5 and scalar 3-brane on AdS5 X S1.

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arXiv2002

New variant of N=4 superconformal mechanics

Proceeding from a nonlinear realization of the most general N=4, d=1 superconformal symmetry, associated with the supergroup D(2,1;alpha), we construct a new model of nonrelativistic N=4 superconformal mechanics. In the bosonic sector it combines the worldline dilaton with the fields parametrizing the R-symmetry coset S^2 ~ SU(2)/U(1). We present invariant off-shell N=4 and N=2 superfield actions for this system and show the existence of an independent N=4 superconformal invariant which extends the dilaton potential. The extended supersymmetry requires this potential to be accompanied by a d=1 WZW term on S^2. We study the classical dynamics of the bosonic action and the geometry of its sigma-model part. It turns out that the relevant target space is a cone over S^2 for any non-zero alpha \neq \pm 1/2. The constructed model is expected to be related to the `relativistic' N=4 mechanics of the AdS_2 times S^2 superparticle via a nonlinear transformation of the fields and the time variable.

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arXiv2002

AdS_2/CFT_1, Canonical Transformations and Superconformal Mechanics

We propose a simple conformal mechanics model which is classically equivalent to a charged massive particle propagating near the AdS_2\times S^2 horizon of an extreme Reissner-Nordström black hole. The equivalence holds for any finite value of the black hole mass and with both the radial and angular degrees of freedom of the particle taken into account. It is ensured by the existence of a canonical transformation in the Hamiltonian formalism. Using this transformation, we construct the Hamiltonian of a N=4 superparticle on AdS_2\times S^2 background.

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arXiv2002

AdS/CFT Equivalence Transformation

We show that any conformal field theory in d-dimensional Minkowski space, in a phase with spontaneously broken conformal symmetry and with the dilaton among its fields, can be rewritten in terms of the static gauge (d-1)-brane on AdS_(d+1) by means of an invertible change of variables. This nonlinear holographic transformation maps the Minkowski space coordinates onto the brane worldvolume ones and the dilaton onto the transverse AdS brane coordinate. One of the consequences of the existence of this map is that any (d-1)-brane worldvolume action on AdS_(d+1)\times X^m (with X^m standing for the sphere S^m or more complicated curved manifold) admits an equivalent description in Minkowski space as a nonlinear and higher-derivative extension of some conventional conformal field theory action, with the conformal group being realized in a standard way. The holographic transformation explicitly relates the standard realization of the conformal group to its field-dependent nonlinear realization as the isometry group of the brane AdS_(d+1) background. Some possible implications of this transformation, in particular, for the study of the quantum effective action of N=4 super Yang-Mills theory in the context of AdS/CFT correspondence, are briefly discussed.

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arXiv2002

Conformal and Superconformal Mechanics Revisited

We find, at the Lagrangian off-shell level, the explicit equivalence transformation which relates the conformal mechanics of De Alfaro, Fubini and Furlan to the conformal mechanics describing the radial motion of the charged massive particle in the Bertotti-Robinson AdS$_2\times S^2$ background. Thus we demonstrate the classical equivalence of these two systems which are usually regarded as essentially different ``old'' and ``new'' conformal mechanics models. We also construct a similar transformation for N=2, $SU(1,1|1)$ superconformal mechanics in N=2 superfield formulation. Performing this transformation in the action of the N=2 superconformal mechanics, we find an off-shell superfield action of N=2 superextension of Bertotti-Robinson particle. Such an action has not been given before. We show its on-shell equivalence to the AdS$_2$ superparticle action derived from the spontaneous partial breaking of $SU(1,1|1)$ superconformal symmetry treated as the N=2 AdS$_2$ supersymmetry.

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arXiv2001

Quantum mechanics of superparticle with 1/4 supersymmetry breaking

We study quantum mechanics of a massive superparticle in d=4 which preserves 1/4 of the target space supersymmetry with eight supercharges, and so corresponds to the partial breaking N=8 down to N=2. Its worldline action contains a Wess-Zumino term, explicitly breaks d=4 Lorentz symmetry and exhibits one complex fermionic kappa-symmetry. We perform the Hamiltonian analysis of the model and quantize it in two different ways, with gauge-fixed kappa-symmetry and in the Gupta-Bleuler formalism. Both approaches give rise to the same supermultiplet structure of the space of states. It contains three irreducible N=2 multiplets with the total number of (4+4) complex on-shell components. These states prove to be in one-to-one correspondence with the de Rham complex of p-forms on a three-dimensional subspace of the target x-manifold. We analyze the vacuum structure of the model and find that the non-trivial vacua are given by the exact harmonic one- and two-forms. Despite the explicit breaking of the d=4 Lorentz symmetry in the fermionic sector, the d=4 mass-shell condition is still valid in the model.

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arXiv2001

Partial Supersymmetry Breaking and AdS4 Supermembrane

We consider partial spontaneous breaking of N=1 AdS4 supersymmetry OSp(1|4) down to N=1, d=3 Poincare supersymmetry in the nonlinear realizations framework. We construct the corresponding worldvolume Goldstone superfield action and show that it describes the N=1 AdS4 supermembrane. It enjoys OSp(1|4) supersymmetry realized as a field-dependent modification of N=1, d=3 superconformal symmetry and goes into the superfield action of ordinary N=1, D=4 supermembrane in the flat limit. Its bosonic core is the Maldacena-type conformally invariant action of the AdS4 membrane. We show how to reproduce the latter action within a nonlinear realization of the AdS4 group SO(2,3). The same universal nonlinear realizations techniques can be used to construct conformally-invariant worldvolume actions for (d-2)-branes in generic AdSd spaces.

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arXiv2001

Superbranes and Super Born-Infeld Theories from Nonlinear Realizations

We describe, on a few instructive examples, a systematic way of deducing the superfield equations of motion of superbranes in the approach of partial breaking of global supersymmetry (PBGS) from the nonlinear-realizations formalism. For D-branes these equations simultaneously represent the appropriate supersymmetric Born-Infeld theories. We also discuss how to construct an off-shell superfield action for the $N=2, d=4$ Dirac-Born-Infeld theory corresponding to the partial supersymmetry breaking $N=4 \to N=2$ in $d=4$.

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arXiv2001

Towards the complete N=2 superfield Born-Infeld action with partially broken N=4 supersymmetry

We propose a systematic way of constructing $N=2, d=4$ superfield Born-Infeld action with a second nonlinearly realized N=2 supersymmetry. The latter, together with the manifest N=2 supersymmetry, form a central-charge extended $N=4, d=4$ supersymmetry. We embed the Goldstone-Maxwell N=2 multiplet into an infinite-dimensional off-shell supermultiplet of this N=4 supersymmetry and impose an infinite set of covariant constraints which eliminate all extra N=2 superfields through the Goldstone-Maxwell one. The Born-Infeld superfield Lagrangian density is one of these composite superfields. The constraints can be solved by iterations to any order in the fields. We present the sought N=2 Born-Infeld action up to the 10th order. It encompasses the action found earlier by Kuzenko and Theisen to the 8th order from a self-duality requirement. This is a strong indication that the complete N=2 Born-Infeld action with partially broken N=4 supersymmetry is also self-dual.

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arXiv2001

Partial spontaneous breaking of two-dimensional supersymmetry

We construct low-energy Goldstone superfield actions describing various patterns of the partial spontaneous breakdown of two-dimensional N=(1,1), N=(2,0) and N=(2,2) supersymmetries, with the main focus on the last case. These nonlinear actions admit a representation in the superspace of the unbroken supersymmetry as well as in a superspace of the full supersymmetry. The natural setup for implementing the partial breaking in a self-consistent way is provided by the appropriate central extensions of D=2 supersymmetries, with the central charges generating shift symmetries on the Goldstone superfields. The Goldstone superfield actions can be interpreted as manifestly world-sheet supersymmetric actions in the static gauge of some superstrings and D1-branes in D=3 and D=4 Minkowski spaces. As an essentially new example, we elaborate on the action representing the 1/4 partial breaking pattern N=(2,2) -> N=(1,0).

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arXiv2000

N=2 and N=4 supersymmetric Born-Infeld theories from nonlinear realizations

Starting from nonlinear realizations of the partially broken central-charge extended N=4 and N=8 Poincaré supersymmetries in D=4, we derive the superfield equations of N=2 and N=4 Born-Infeld theories. The basic objects are the bosonic Goldstone N=2 and N=4 superfields associated with the central charge generators. By construction, the equations are manifestly N=2 and N=4 supersymmetric and enjoy covariance under another nonlinearly realized half of the original supersymmetries. They provide a manifestly worldvolume supersymmetric static-gauge description of D3-branes in D=6 and D=10. For the N=2 case we find, to lowest orders, the equivalence transformation to the standard N=2 Maxwell superfield strength and restore, up to the sixth order, the off-shell N=2 Born-Infeld action with the second hidden N=2 supersymmetry.

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arXiv2000

Double-vector multiplet and partially broken N=4, d=3 supersymmetry

We elaborate on a new N=2, d=3 supermultiplet (double-vector multiplet) with a non-trivial off-shell realization of the central charge. Its bosonic sector comprises two abelian gauge vector fields forming an SO(2) vector. We present a superfield formulation of this multiplet in the central-charge extended N=2, d=3 superspace and then employ it, in the framework of the nonlinear realizations approach, as the Goldstone one for the partial breaking N=4 -> N=2 in three dimensions. The covariant equations of motion for the self-interacting Goldstone superfield arise as a natural generalization of the free ones and are interpreted as the worldvolume supersymmetric form of the equations of motion of a N=4 D2-brane. For the vector fields we find a coupled nonlinear system of Born-Infeld type and demonstrate its dual equivalence to the d=5 membrane. The double-vector multiplet can be fused with some extra N=2, d=3 multiplet to form an off-shell N=4, d=3 supermultiplet.

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arXiv2000

Superworldvolume dynamics of superbranes from nonlinear realizations

Based on the concept of the partial breaking of global supersymmetry (PBGS), we derive the worldvolume superfield equations of motion for $N=1, D=4$ supermembrane, as well as for the space-time filling D2- and D3-branes, from nonlinear realizations of the corresponding supersymmetries. We argue that it is of no need to take care of the relevant automorphism groups when being interested in the dynamical equations. This essentially facilitates computations. As a by-product, we obtain a new polynomial representation for the $d=3,4$ Born-Infeld equations, with merely a cubic nonlinearity.

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arXiv1999

1/4 PBGS and Superparticle Actions

We construct the worldline superfield massive superparticle actions which preserve 1/4 portion of the underlying higher-dimensional supersymmetry. We consider the cases of N=4/N=1 and N=8/N=2 partial breaking. In the first case we present the corresponding Green-Schwarz type target superspace action with one kappa supersymmetry. In the second case we find out two possibilities, one of which is a direct generalization of the N=4/N=1 case, while another is essentially different.

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arXiv1999

1/4 Partial Breaking of Global Supersymmetry and New Superparticle Actions

We construct the worldline superfield massive superparticle actions which preserve 1/4 portion of the underlying higher-dimensional supersymmetry. The rest of supersymmetry is spontaneously broken and realized by nonlinear transformations. We consider the cases of N=4 to N=1 and N=8 to N=2 partial breaking. In the first case we present the corresponding Green-Schwarz type target superspace action with one $κ$-supersymmetry. It is related to the superfield action via a field redefinition. In the second case we find out two possible models, one of which is a direct generalization of the N=4 to N=1 case, while another is essentially different. For the first model we formulate Green-Schwarz type action with two kappa supersymmetries. We elaborate on the bosonic part of the superfield action for the second model and find that only in two special limits it takes the standard Nambu-Goto form. In the general case it is determined by a fourth-order algebraic equation. The characteristic common feature of these new superparticle models is that the algebras of their spontaneously broken supersymmetries are non-trivial truncations of the general extensions of N=1 and N=2 Poincare D=4 superalgebras by tensorial central charges.

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arXiv1999

N=4 Sugawara construction on affine sl(2|1), sl(3) and mKdV-type superhierarchies

The local Sugawara constructions of the "small" N=4 SCA in terms of supercurrents of N=2 extensions of the affinization of the sl(2|1) and sl(3) algebras are investigated. The associated super mKdV type hierarchies induced by N=4 SKdV ones are defined. In the sl(3) case the existence of two inequivalent Sugawara constructions is found. The long one involves all the affine sl(3)-valued currents, while the "short" one deals only with those from the subalgebra sl(2)\oplus u(1). As a consequence, the sl(3)-valued affine superfields carry two inequivalent mKdV type super hierarchies induced by the correspondence between "small" N=4 SCA and N=4 SKdV hierarchy. However, only the first hierarchy posseses genuine global N=4 supersymmetry. We discuss peculiarities of the realization of this N=4 supersymmetry on the affine supercurrents.

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