4,343 research outputs found
Symmetries of the refined D1/D5 BPS spectrum
We examine the large 1/4-BPS spectrum of the symmetric orbifold CFT
Sym deformed to the supergravity point in moduli space for and
. We consider refinement under both left- and right-moving
symmetries of the superconformal algebra, and decompose the spectrum into
characters of the algebra. We find that at large the character
decomposition satisfies an unusual property, in which the degeneracy only
depends on a certain linear combination of left- and right-moving quantum
numbers, suggesting deeper symmetry structure. Furthermore, we consider the
action of discrete symmetry groups on these degeneracies, where certain
subgroups of the Conway group are known to play a role. We also comment on the
potential for larger discrete symmetry groups to appear in the large limit.Comment: 27 pages + appendices; v2: minor change
Twining Genera of (0,4) Supersymmetric Sigma Models on K3
Conformal field theories with (0,4) worldsheet supersymmetry and K3 target
can be used to compactify the E8xE8 heterotic string to six dimensions in a
supersymmetric manner. The data specifying such a model includes an appropriate
configuration of 24 gauge instantons in the E8xE8 gauge group to satisfy the
constraints of anomaly cancellation. In this note, we compute twining genera -
elliptic genera with appropriate insertions of discrete symmetry generators in
the trace - for (0,4) theories with various instanton embeddings. We do this by
constructing linear sigma models which flow to the desired conformal field
theories, and using the techniques of localization. We present several examples
of such twining genera which are consistent with a moonshine relating these
(0,4) models to the finite simple sporadic group M24.Comment: 22 pages, 3 tables. We thank T. Eguchi and K. Hikami for permission
to copy our Tables 2 and 3 (M24 character table and q-expansions of some
twining genera in the (4,4) sigma model with K3 target) from their article
arXiv:1008.492
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