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R. Siebelink

Publications and source records attributed to R. Siebelink.

9 recordsLinked to original sources
arXiv1998

R-Current Correlators in N=4 Super Yang-Mills Theory from Anti-de Sitter Supergravity

We test the conjectured relationship between N=4 super Yang-Mills theory in four dimensions and IIB supergravity compactified on $AdS_5\times S_5$ by computing the two- and three-point functions of R-symmetry currents. We observe that the integral expressions describing the general three-point correlator on the supergravity side have a structure similar to one-loop triangle diagrams in N=4 super Yang-Mills theory. This allows us to compare the expressions on both sides of the AdS/CFT correspondence without the technical complications of the loop integrations. We confirm that the two- and three-point correspondence arises at only one-loop in the N=4 super Yang-Mills theory. Higher-point functions as well as further three-point functions may be analyzed similarly.

hep-th↗
arXiv1998

The low-energy effective action for perturbative heterotic strings on $K_3 \times T^2$ and the d=4 N=2 vector-tensor multiplet

We consider d=4 N=2 supergravity theories which serve as low-energy effective actions for heterotic strings on K_3 \times T^2. At the perturbative level we construct a new version of the heterotic effective action in which the axion has been traded for an antisymmetric tensor field. In the string frame the antisymmetric tensor doesn't transform under Poincaré supersymmetry into the dilaton-dilatini system. This indicates that in this frame the antisymmetric tensor field and the dilaton are not contained in an N=2 vector-tensor multiplet. Instead, we find that the heterotic dilaton is part of a compensating hypermultiplet, whereas the antisymmetric tensor is part of the gravitational multiplet. In order to obtain our results we use superconformal techniques. This enables us to comment on the range of applicability of this particular framework.

hep-th↗
arXiv1998

Vector-tensor multiplets

We review the coupling of N=2 supergravity to vector-tensor multiplets, based on the method of superconformal multiplet calculus.

hep-th↗
arXiv1995

The Vector-Tensor Supermultiplet with Gauged Central Charge

The vector-tensor multiplet is coupled off-shell to an N=2 vector multiplet such that its central charge transformations are realized locally. A gauged central charge is a necessary prerequisite for a coupling to supergravity and the strategy underlying our construction uses the potential for such a coupling as a guiding principle. The results for the action and transformation rules take a nonlinear form and necessarily include a Chern-Simons term. After a duality transformation the action is encoded in a homogeneous holomorphic function consistent with special geometry.

hep-th↗
arXiv1993

Regularisation of non-local actions in two-dimensional field theories

Taking the induced action for gauge fields coupled to affine currents as an example, we show how loop calculations in non-local two-dimensional field theories can be regulated. Our regularisation method for one loop is based on the method of Pauli and Villars. We use it to calculate the renormalisation factors for the corresponding effective actions, clearing up some discrepancies in the literature. In particular, it will be shown explicitly that vector gauge transformation invariance and Haar invariance of functional integral measures impose different requirements, but they are related by a counterterm (which is local in terms of group variables). For higher loops, we use the method of covariant derivatives combined with Pauli-Villars to argue that the one loop result remains unaltered.

hep-th↗
arXiv1993

Hiding Anomalies

Anomalies can be anticipated at the classical level without changing the classical cohomology, by introducing extra degrees of freedom. In the process, the anomaly does not quite disappear. We show that, in fact, it is shifted to new symmetries that come with the extra fields.

hep-th↗
arXiv1992

The regularized BRST Jacobian of pure Yang-Mills theory

The Jacobian for infinitesimal BRST transformations of path integrals for pure Yang-Mills theory, viewed as a matrix $\unity +ΔJ$ in the space of Yang-Mills fields and (anti)ghosts, contains off-diagonal terms. Naively, the trace of $ΔJ$ vanishes, being proportional to the trace of the structure constants. However, the consistent regulator $\cR$, constructed from a general method, also contains off-diagonal terms. An explicit computation demonstrates that the regularized Jacobian $Tr\ ΔJ\exp -\cR /M^2$ for $M^2\rightarrow \infty $ is the variation of a local counterterm, which we give. This is a direct proof at the level of path integrals that there is no BRST anomaly.

hep-th↗
arXiv1992

Nonlocal regularisation and two-dimensional induced actions

We present an invariant regularisation scheme to compute two dimensional induced gauge theory actions, that is local in Polyakov's variables, but nonlocal in the original gauge potentials. Our method sheds light on the locality of this induced action, and leads to a straightforward proof that the $\varepsilon$-anomaly in $W_3$-gravity is completely given by the one loop term.

hep-th↗