Multi-Centered Invariants, Plethysm and Grassmannians

TL;DR

This paper develops algebraic and geometric methods to determine invariant polynomials related to multi-centered black hole solutions in supergravity, focusing on symmetries and invariants in the context of Grassmannians and group theory.

Contribution

It introduces a combined algebraic and geometric framework for constructing invariants in multi-centered black hole models, especially for groups of type E7 and the stu model.

Findings

Explicit basis for degree-12 invariants in 3-centered black holes

Methods applicable to symmetric scalar manifolds in supergravity

Analysis of invariants under horizontal and duality symmetries

Abstract

Motivated by multi-centered black hole solutions of Maxwell-Einstein theories of (super)gravity in D=4 space-time dimensions, we develop some general methods, that can be used to determine all homogeneous invariant polynomials on the irreducible (SL_h(p,R) x G4)-representation (p,R), where p denotes the number of centers, and SL_h(p,R) is the "horizontal" symmetry of the system, acting upon the indices labelling the centers. The black hole electric and magnetic charges sit in the symplectic representation R of the generalized electric-magnetic (U-)duality group G4. We start with an algebraic approach based on classical invariant theory, using Schur polynomials and the Cauchy formula. Then, we perform a geometric analysis, involving Grassmannians, Pluecker coordinates, and exploiting Bott's Theorem. We focus on non-degenerate groups G4 "of type E7" relevant for (super)gravities whose (vector multiplets') scalar manifold is a symmetric space. In the triality-symmetric stu model of N=2 supergravity, we explicitly construct a basis for the 10 linearly independent degree-12 invariant polynomials of 3-centered black holes.