arXiv subjects
Publications and source records attributed to Andreas Gustavsson.
We use the AdS/CFT correspondence to show that for two spherical Wilson surfaces, both in the fundamental representation of $SU(N)$ gauge group, in the six-dimensional $(2,0)$ theory, in the large $N$ limit there is a first order Gross-Ooguri phase transition at a certain critical separation distance that we obtain numerically.
We introduce a nonabelian surface holonomy that is constructed from a one-form gauge potential that takes values in a loop algebra of the $U(N)$ gauge group. The surface holonomy parallel transports a nonabelian string. Although it is not manifest in our formulation, we will see that our nonabelian surface holonomy is invariant under reparametrizations of the surface.
We analyze the nonabelian surface holonomy on a bipartite hypercubic lattice following a proposal in arXiv:1002.4636 [hep-th]. The bipartite structure of the lattice enables us to introduce spike string configurations. These spikes play a crucial role for the time evolution of the string when the total number of color indices changes.
We reformulate the abelian tensor multiplet on a curved spacetime with at least two supercharges in a cohomological form where all the bosonic and fermionic fields become tensor fields. These tensor fields are rewritten as fields in loop space by a transgression map. There are two lightlike conformal Killing vectors. By decomposing the spacetime tensor fields in transverse and parallel components to these Killing vectors, we obtain the equations of motion in loop space by closing the supersymmetry variations on-shell. We generalize to nonabelian gauge groups. By closing supersymmetry variations we obtain nonabelian fermionic equations of motion in loop space.
We show that the (1,0) tensor and hypermultiplet supersymmetry variations can be uplifted to loop space. Upon dimensional reduction we make contact with abelian five-dimensional super Yang-Mills, which has a nonabelian generalization that we subsequently uplift back to loop space where we conjecture a nonabelian generalization of the (1,0) supersymmetry variations and demonstrate their on-shell closure.
We study 6d $(1,0)$ superconformal theories. These have a natural lightlike conformal Killing vector, the Dirac current. We perform a conformal dimensional reduction along the Dirac current down to five-dimensions in such a way that we always preserve at least two real supercharges
Dimensional reduction of the M5 brane on a Lorentzian manifold along a lightlike direction results in a five-dimensional gauge theory, which can be reformulated covariantly in six dimensions, where one puts the Lie derivatives along the lightlike direction of all fields to zero as constraints. Without imposing these constraints, we have a nonsupersymmetric six-dimensional gauge theory that we may expect shall have a six dimensional gauge symmetry. However this gauge symmetry has an anomaly for certain Lorentzian six-manifolds. We show that this gauge anomaly can be canceled by adding a WZW theory in the 2d space that is spanned by two lightlike directions.
We obtain a Lagrangian for a lightlike dimensional reduction of the nonabelian M5 brane theory in six dimension. We assume that the six-manifold has at least one conformal Killing spinor and two commuting lightlike Killing vector fields, and we perform the dimensional reduction along one of these lightlike directions.
We study M5 branes on $\mathbb{R}^{1,1} \times$Taub-NUT that we view as a singular fibration. Reducing the M5 branes along the fiber gives 5d SYM. Due to the singularity, this 5d theory has a gauge anomaly and it is not supersymmetric. To cure these problems we add a supersymmetric gauged chiral WZW theory on the 2d submanifold where the circle fiber vanishes. In addition we add a mass term for the five scalar fields located on this submanifold. With all this, we obtain a fully supersymmetric and gauge invariant theory.
We study dimensional reduction of M5 branes on a circle bundle when the supersymmetry parameter is not constant along the circle. When the gauge group is Abelian and the fields appear quadratically in the Lagrangian, we can always obtain a supersymmetric five-dimensional theory by keeping fermionic nonzero modes that match with the corresponding nonzero modes of the supersymmetry parameter, and by keeping the zero modes for the bosonic fields as usual. But a supersymmetric non-Abelian generalization can be found only under special circumstances. One instance where we find a non-Abelian supersymmetric generalization is when we perform dimensional reduction along a null direction.
We present a nonabelian Lagrangian that appears to have $(2,0)$ superconformal symmetry and that can be coupled to a supergravity background. But for our construction to work, we have to break this superconformal symmetry by imposing as a constraint on top of the Lagrangian that the fields have vanishing Lie derivatives along a Killing direction.
We examine how the Einstein-Hilbert action is renormalized by adding the usual counterterms and additional corner counterterms when the boundary surface has corners. A bulk geometry asymptotic to $H^{d+1}$ can have boundaries $S^k \times H^{d-k}$ and corners for $0\leq k<d$. We show that the conformal anomaly when $d$ is even is independent of $k$. When $d$ is odd the renormalized action is a finite term that we show is independent of $k$ when $k$ is also odd. When $k$ is even we were unable to extract the finite term using the counterterm method and we address this problem using instead the Kounterterm method. We also compute the mass of a two-charged black hole in AdS$_7$ and show that background subtraction agrees with counterterm renormalization only if we use the infinite series expansion for the counterterm.
We compute the conformal anomaly of the abelian M5 brane on a conical deformation $S^6_q$ of the round six-sphere. Our results agree with corresponding results on $S^1 \times \mathbb{H}^5$ that were obtained in arXiv:1511.00313. For the free energies we obtain missing Casimir energy contributions, inconsequental for the Renyi entropies, and we obtain the proposed constant shift for the Renyi entropy of the selfdual two-form.
We compute the conformal anomaly of a nonabelian M5 brane on $S^1_q\times H^5$ in the large $N$ limit by using the gravity dual of a black hole. We also obtain a general formula for this conformal anomaly for any gauge group by combining various results already present in the literature. From the conformal anomaly we extract the Casimir energy on $\mathbb{R} \times S^5$. We find agreement with the proposal in arXiv:1507.08553.
We study the abelian M5 brane on $S^6$. From the spectrum we extract a series expansion for the heat kernel. In particular we determine the normalization for the coefficient $a$ in the M5 brane conformal anomaly. When we compare our result with what one gets by computing the Hadamard-Minakshisundaram-DeWitt-Seeley coefficients from local curvature invariants on $S^6$, we first find a mismatch of one unit. This mismatch is due to an overcounting of one zero mode. After subtracting this contribution, we finally find agreement. We perform dimensional reduction along a singular circle fiber to five dimensions where we find the conformal anomaly vanishes.
We compactify the abelian 6d (1,0) tensor multiplet on a circle bundle, thus reducing the theory down to 5d SYM while keeping all the KK modes. This abelian classical field theory, when interpreted suitably, has a nonlocal superconformal symmetry. Furthermore, a nonabelian generalization, where all the KK modes are kept, is possible for the nonlocal superconformal symmetry, whereas for the local superconformal symmetry we can only realize a subgroup.
If one compactifies the Abelian $(1,0)$ tensor multiplet on a circle, one finds 5d SYM for the zero modes. For the Kaluza-Klein modes one can likewise find a Lagrangian description in 5d \cite{Bonetti:2012st}. Since in 5d we have an ordinary YM gauge potential, one may look for a non-Abelian generalization and indeed such a non-Abelian generalization was found in \cite{Bonetti:2012st}. In this paper, we study this non-Abelian generalization for the $(1,0)$ tensor multiplet in detail. We obtain the supersymmetry variations that we close on-shell. This way we get the fermionic equation of motion and a modified selfduality constraint.
We assume the existence of a background vector field that enables us to make an ansatz for the superconformal transformations for the non-Abelian 6d $(1,0)$ tensor multiplet. Closure of supersymmetry on generators of the conformal algebra, requires that the vector field is Abelian, has scaling dimension minus one and that the supersymmetry parameter as well as all the fields in the tensor multiplet have vanishing Lie derivatives along this vector field. We couple the tensor multiplet to a hypermultiplet and obtain superconformal transformations that we close off-shell.