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Bindusar Sahoo

Publications and source records attributed to Bindusar Sahoo.

At least 19 recordsLinked to original sources

Supersymmetry and Attractors in N = 4 Supergravity: The Superconformal Approach

In this paper, we study the attractor mechanism for extremal, spherically symmetric black holes in pure, untruncated, N=4 Poincar\'e supergravity, which we demonstrate numerically. We further study the supersymmetries preserved by these attractor solutions by focussing specifically on the constant moduli solutions and show that they always preserve 1/4$^{th}$ of the total supersymmetries. We also give an argument that even the attractor solutions with a ``non-constant'' moduli would preserve 1/4$^{th}$ of the total supersymmetries. This would mean that in pure N=4 supergravity there exist no attractor solutions which are non-supersymmetric although they could in-principle exist in a matter coupled theory. We use the framework of conformal supergravity in our analysis, which is a manifestly off-shell framework and considerably simplifies the Killing spinor analysis.

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Supersymmetric truncation of N=3 dilaton Weyl multiplet

We perform all possible supersymmetric truncations of the four-dimensional N=3 dilaton Weyl multiplet, which realizes an R-symmetry $SU(2) \times U(1) \times U(1)$, to N=2. A particular truncation procedure does not break any of the R-symmetries and leads to the known N=2 vector-dilaton Weyl multiplet and the N=2 vector multiplet. A different truncation procedure breaks the SU(2) part of the R-symmetry to U(1) and leads to a 32+32 off-shell representation of N=2 conformal supergravity with a partially broken R-symmetry. Independently, we construct another 32+32 off-shell multiplet in N=2 conformal supergravity by coupling the N=2 scalar-tensor multiplet to the N=2 standard Weyl multiplet and using the scalar fields present in the scalar-tensor multiplet to break the SU(2) R-symmetry to U(1). We then establish the equivalence between these two multiplets through a mapping. We observe that this 32+32 multiplet is gauge equivalent to a Poincar\'e supergravity multiplet as it has all the compensators necessary to go from conformal supergravity to Poincar\'e supergravity.

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Only Flat Spacetime is Full BPS in Four Dimensional N=3 and N=4 Supergravity

We investigate the fully supersymmetric solutions in a class of N=3 and N=4 higher derivative Poincar\'e supergravity theories. These class of theories are obtained within the framework of conformal supergravity using the standard Weyl multiplet and contains a set of terms related to the Weyl square term by supersymmetry. We work in the superconformal formalism and show that flat spacetime is the only fully supersymmetric solution in these theories. However, in N=2 Poincar\'e supergravity theories that falls into the same class, two fully supersymmetric stationary solutions exist: Bertotti-Robinson geometry ($AdS_2\times S^2$) and flat spacetime, which are known in the literature. We discuss the reason behind the richer vacua in N=2 supergravity compared to its N=3 and N=4 cousins.

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Variant dilaton Weyl Multiplet for N=3 conformal supergravity in four dimensions

We construct a new dilaton Weyl multiplet for $\mathcal{N}=3$ conformal supergravity in four dimensions. The R-symmetry realized on this dilaton Weyl multiplet is $SU(2) \times U(1) \times U(1)$. The construction follows a two-step procedure. Firstly, two on-shell vector multiplets are coupled to the standard Weyl multiplet. Secondly, using the field equations of the vector multiplets, some of the auxiliary fields of the standard Weyl multiplet are solved in terms of the fields belonging to the vector multiplets and some dual gauge fields. The remaining fields of the standard Weyl multiplet combine with the vector multiplet fields and the dual gauge fields to constitute the new dilaton Weyl multiplet.

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Scalar-Tensor multiplet in four dimensional N=2 conformal supergravity

We study various N=2 multiplets in four dimensions by looking at the supersymmetric truncation of four dimensional N=3 multiplets. Under supersymmetric truncation, the off-shell N=3 Weyl multiplet reduces to the off-shell N=2 Weyl multiplet and the off-shell N=2 vector multiplet (which we will refer to as the central charge multiplet). Under the same truncation, the on-shell N=3 vector multiplet reduces to the on-shell N=2 vector multiplet and an on-shell massive hypermultiplet with a broken rigid SU(2) and a non-trivial central charge transformation. We use the field equations of this hypermultiplet to eliminate some of the fields of the central charge multiplet in terms of the fields of the hypermultiplet and a dual tensor gauge field (similar in spirit to how a dilaton Weyl multiplet is constructed). This results in a new off-shell matter multiplet, with 8+8 degrees of freedom, containing scalar fields and a tensor gauge field, which we refer to as the scalar-tensor multiplet.

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Dilaton Weyl multiplets for $N = 3$ conformal supergravity in four dimensions

We construct a dilaton Weyl multiplet for $N = 3$ conformal supergravity in four dimensions. We couple an on-shell vector multiplet to the standard Weyl multiplet and use the field equations of the vector multiplet to replace some of the components of the auxiliary fields of the standard Weyl multiplet with the fields of the vector multiplet and some dual gauge fields. The R-symmetry of the multiplet is $SU(2) \times U(1) \times U(1)$. Furthermore, we gauge fix one of the two $U(1)$ symmetries and rewrite the result for the dilaton Weyl multiplet with $SU(2) \times U(1)$ R-symmetry.

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$SU(2)\times SU(2)$ dilaton Weyl multiplets for maximal conformal supergravity in four, five, and six dimensions

New dilaton Weyl multiplets are constructed in four and five space-time dimensions for $N=4$ and $N=2$ conformal supergravity respectively. They are constructed from a mixture of the old dilaton weyl multiplets with an on-shell vector multiplet. The old dilaton Weyl multiplets have a $USp(4)$ R-symmetry group whereas the new multiplets have $SU(2)\times SU(2)$ R-symmetry, which is a subgroup of $USp(4)$. In six dimensions, for the first time we construct a dilaton Weyl multiplet for $(2,0)$ conformal supergravity from a mixture of the standard Weyl multiplet and a tensor multiplet. The R-symmetry group for the dilaton Weyl multiplet in six dimensions is also $SU(2)\times SU(2)$.

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Torus reduction of maximal conformal supergravity

We consider the dimensional reduction of N=(2,0) conformal supergravity in six dimensions on a two-torus to N=4 conformal supergravity in four dimensions. At the level of kinematics, the six-dimensional Weyl multiplet is shown to reduce to a mixture of the N=4 Weyl and vector multiplets, which can be reinterpreted as a new off-shell multiplet of N=4 conformal supergravity. Similar multiplets have been constructed in other settings and are referred to as dilaton Weyl multiplets. We derive it here for the first time in a maximally supersymmetric context in four dimensions. Furthermore, we present the non-linear relations between all the six- and four-dimensional bosonic and fermionic fields, that are obtained by comparing the off-shell supersymmetry transformation rules.

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N=2 conformal supergravity in five dimensions

N=2 conformal supergravity in five dimensions is constructed via a systematic off-shell reduction scheme from maximal conformal supergravity in six dimensions which is (2,0). The dimensional reduction of the (2,0) Weyl multiplet in six dimensions gives us the Weyl multiplet in five dimensions which is a dilaton Weyl multiplet as it has a dilaton scalar. The dimensional reduction of the (2,0) tensor multiplet in six dimensions gives us the N=2 vector multiplet in five dimensions coupled to conformal supergravity. We also comment on Nahm's classification regarding the non-existence of an N=2 superconformal algebra in five dimensions and why it does not contradict the existence of N=2 conformal supergravity in five dimensions that is constructed in this paper.

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Higher derivative invariants in four dimensional N=3 Poincare supergravity

In this paper, we use the superconformal approach to derive the higher derivative action for N = 3 Poincare supergravity in four space-time dimensions. We first study the coupling of N = 3 vector multiplets to conformal supergravity. Thereafter we combine it with the pure N = 3 conformal supergravity action and use a minimum of three vector multiplets as compensators to arrive at Poincare supergravity with higher derivative corrections. We give a general prescription on how to eliminate the auxiliary fields in an iterative manner and obtain the supergravity action order by order in derivatives. We also show that the truncation of the action at fourth order in derivatives is a consistent truncation.

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N = 3 Conformal Supergravity in Four Dimensions

In this paper, we derive the action for $N=3$ conformal supergravity in four space-time dimensions. We construct a density formula for $N=3$ conformal supergravity based on the super form action principle. Finally, we embed the $N=3$ Weyl multiplet in the density formula to obtain the invariant action for $N=3$ conformal supergravity. There are two inequivalent embeddings by changing a particular coefficient from real to imaginary. They lead to invariant actions, which will either be the supersymmetrization of the Weyl square term or the Pontryagin density in the eventuality of gauge fixing to Poincaré supergravity. As a consistency check of our formalism, we will show that the supersymmetrization of the Pontryagin density is a total derivative. We will demonstrate this for purely bosonic terms. We will also present the complete action for the supersymmetrization of the Weyl square term. We also discuss consistent truncation of $N=4$ Weyl multiplet to $N=3$ Weyl multiplet and use it for a robust check of our results using the earlier known results in $N=4$ conformal supergravity.

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Relaxed hypermultiplet in four dimensional N=2 conformal supergravity

Superconformal matter multiplets play a crucial role in the construction of Poincare supergravity invariants. Off-shell multiplets allow for construction of general matter couplings in supergravity. In Nucl. Phys. B214 (1983) 519-531, relaxed hypermultiplet was constructed in rigid supersymmetry which on coupling with the real scalar multiplet allowed for an off-shell formulation of the rigid hypermultiplet. In this paper, we extend the relaxed hypermultiplet to conformal supergravity. For consistency with the superconformal algebra, we find that the fields have to be allowed to transform in a non-canonical way under SU(2) symmetry. We find suitable field redefinitions to obtain fields which are irreducible representations of SU(2) R-symmetry and present the full non-linear transformation rule.

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New higher derivative action for tensor multiplet in N=2 conformal supergravity in four dimensions

We will use the covariant superform approach to develop a new density formula for $\mathcal{N}=2$ conformal supergravity which is based on a fermionic multiplet whose lowest component is a dimension-5/2 spinor. We will show that this density formula admits an embedding of the real scalar multiplet of [arXiv:1712.02309]. Upon using the embedding of the tensor multiplet into the real scalar multiplet, we will construct a new higher derivative action of the tensor multiplet in $\mathcal{N}=2$ conformal supergravity.

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N=4 conformal supergravity: the complete actions

The most general class of 4D N=4 conformal supergravity actions depends on a holomorphic function of the scalar fields that parametrize an SU(1,1)/U(1) coset space. The bosonic sector of these actions was presented in a letter [arXiv:1609.09083]. Here we provide the complete actions to all orders in the fermion fields. They rely upon a new N=4 density formula, which permits a direct but involved construction. This density formula also recovers the on-shell action for vector multiplets coupled to conformal supergravity. Applications of these results in the context of Poincaré supergravity are briefly discussed.

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Comment on "The N = 3 Weyl Multiplet in Four Dimensions"

N = 3 Weyl multiplet in four dimensions was first constructed in J van Muiden et al (2017) where the authors used the current multiplet approach to obtain the linearized transformation rules and completed the nonlinear variations using the superconformal algebra. The multiplet of currents was obtained by a truncation of the multiplet of currents for the N = 4 vector multiplet. While the procedure seems to be correct, the result suffers from several inconsistencies. The inconsistencies are observed in the transformation rules as well as the field dependent structure constants in the corresponding soft algebra. We take a different approach, and compute the transformation rule as well as the corresponding soft algebra by demanding consistency.

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A 24+24 real scalar multiplet in four dimensional N=2 conformal supergravity

Starting from the 48+48 component multiplet of supercurrents for a rigid N=2 tensor multiplet in four spacetime dimensions, we obtain the transformation of the linearized supergravity multiplet which couples to this supercurrent multiplet. At the linearized level, this 48+48 component supergravity multiplet decouples into the 24+24 component linearized standard Weyl multiplet and a 24+24 component irreducible matter multiplet containing a real scalar field. By a consistent application of the supersymmetry algebra with field dependent structure constants appropriate to N=2 conformal supergravity, we find the full transformation law for this multiplet in a conformal supergravity background. By performing a field redefinition and switching off the conformal supergravity background, the multiplet is equivalent to the one introduced by Howe et al in flat space as a constrained real scalar superfield. We present a set of constraints which can be consistently imposed on this multiplet to obtain a restricted minimal 8+8 off-shell matter multiplet. We also show as an example the precise embedding of the tensor multiplet inside this multiplet.

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$N=2$ dilaton Weyl multiplet in 4D supergravity

We construct the dilaton Weyl multiplet for $N=2$ conformal supergravity in four dimensions. Beginning from an on-shell vector multiplet coupled to the standard Weyl multiplet, the equations of motion can be used to eliminate the supergravity auxiliary fields, following a similar pattern as in five and six dimensions. The resulting 24+24 component multiplet includes two gauge vectors and a gauge two-form and provides a variant formulation of $N=2$ conformal supergravity. We also show how this dilaton Weyl multiplet is contained in the minimal 32+32 Poincare supergravity multiplet introduced by Muller in superspace.

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