Invariants and divergences in half-maximal supergravity theories

TL;DR

This paper analyzes invariants and potential divergences in half-maximal supergravity theories in four and five dimensions, focusing on duality symmetries, anomalies, and the implications for counterterms and finiteness at various loop orders.

Contribution

It provides a detailed examination of invariants and divergences in half-maximal supergravity, highlighting the role of duality anomalies and the constraints on counterterms in different dimensions.

Findings

In D=4, duality anomalies affect divergence restrictions.

A three-loop duality-invariant counterterm exists but is marginally invariant.

In D=5, absence of one-loop anomaly suggests two-loop finiteness.

Abstract

The invariants in half-maximal supergravity theories in D=4,5 are discussed in detail up to dimension eight (e.g. R^4). In D=4, owing to the anomaly in the rigid SL(2,R) duality symmetry, the restrictions on divergences need careful treatment. In pure N=4 supergravity, this anomalous symmetry still implies duality invariance of candidate counterterms at three loops. Provided one makes the additional assumption that there exists a full 16-supercharge off-shell formulation of the theory, counterterms at L>1 loops would also have to be writable as full-superspace integrals. At the three-loop order such a duality-invariant full-superspace integral candidate counterterm exists, but its duality invariance is marginal in the sense that the full-superspace counter-Lagrangian is not itself duality-invariant. We show that such marginal invariants are not allowable as counterterms in a 16-supercharge off-shell formalism. It is not possible to draw the same conclusion when vector multiplets are present because of the appearance of F^4 terms in the SL(2,R) anomaly. In D=5 there is no one-loop anomaly in the shift invariance of the dilaton, and we argue that this implies finiteness at two loops, again subject to the assumption that 16 supercharges can be preserved off-shell.