Minimal representations for simply-laced groups

All simply-laced groups G (and some non-simply laced ones) admit a representation in a quantum phase space of minimal dimension given by the dimension of the smallest nilpotent orbit in G. This representation generalizes the Schrodinger (or metaplectic) representation of the symplectic group Sp(n,R) in the phase space of the n-dimensional harmonic oscillator. The paper ``Minimal representations, spherical vectors, and exceptional theta series I'' (D. Kazhdan, B. Pioline and A. Waldron, hep-th/0107222 ) presents an explicit construction of this representation for all ADE groups and its spherical vector, i.e., the wave function annihilated by all compact generators. This result is an important ingredient in constructing theta series, and conjecturally encodes information about the quantum BPS membrane.

From this site you can download the list of generators for all groups, either in Form output format, or in Mathematica input format:

Form: [ A2 | A3 | A5 | D4 | D5 | E6 | E7 | E8 ]
Mathematica: [ A2 | A3 | A5 | D4 | D5 | E6 | E7 | E8 ]
You may also download all at once in a gzipped tar file.

The positive generators are denoted a#, b#, c#,om for the positive roots, where a# correspond to the grade-0 roots, b# the grade one roots represented as momenta, c# the grade one roots represented as positions, and om the grade 2 highest root. The notation am#,bm#,cm#,mom is used for the negative ones. H# denote the Cartan generators wrt the simple roots, and Hom the Cartan generator for the highest root.

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