Non-extremal D-instantons

TL;DR

This paper constructs the most general non-extremal D-instanton solutions with maximal symmetry, explores their relation to black holes and p-branes in higher dimensions, and discusses their potential role in string theory corrections.

Contribution

It introduces the most general non-extremal D-instanton solutions with maximal symmetry and connects them to higher-dimensional black holes and branes, extending previous extremal solutions.

Findings

Non-extremal D-instantons with maximal symmetry constructed.

Solutions relate to non-extremal Reissner-Nordström black holes.

Potential contribution to R^8-terms in type IIB string theory.

Abstract

We construct the most general non-extremal deformation of the D-instanton solution with maximal rotational symmetry. The general non-supersymmetric solution carries electric charges of the SL(2,R) symmetry, which correspond to each of the three conjugacy classes of SL(2,R). Our calculations naturally generalise to arbitrary dimensions and arbitrary dilaton couplings. We show that for specific values of the dilaton coupling parameter, the non-extremal instanton solutions can be viewed as wormholes of non-extremal Reissner-Nordstr\"om black holes in one higher dimension. We extend this result by showing that for other values of the dilaton coupling parameter, the non-extremal instanton solutions can be uplifted to non-extremal non-dilatonic p-branes in p+1 dimensions higher. Finally, we attempt to consider the solutions as instantons of (compactified) type IIB superstring theory. In particular, we derive an elegant formula for the instanton action. We conjecture that the non-extremal D-instantons can contribute to the R^8-terms in the type IIB string effective action.