17,584 research outputs found
Elliptic genera of ALE and ALF manifolds from gauged linear sigma models
We compute the equivariant elliptic genera of several classes of ALE and ALF
manifolds using localization in gauged linear sigma models. In the sigma model
computation the equivariant action corresponds to chemical potentials for U(1)
currents and the elliptic genera exhibit interesting pole structure as a
function of the chemical potentials. We use this to decompose the answers into
polar terms that exhibit wall crossing and universal terms. We compare our
results to previous results on the large radius limit of the Taub-NUT elliptic
genus and also discuss applications of our results to counting of BPS
world-sheet spectrum of monopole strings in the 5d N=2 super Yang-Mills theory
and self-dual strings in the 6d N=(2,0) theories.Comment: 1+60 page
Three-Charge Black Holes and Quarter BPS States in Little String Theory
We show that the system of NS5-branes wrapping
has non-trivial vacuum structure. Different vacua have different spectra of 1/4
BPS states that carry momentum and winding around the . In one vacuum,
such states are described by black holes; in another, they can be thought of as
perturbative BPS states in Double Scaled Little String Theory. In general, both
kinds of states are present. We compute the degeneracy of perturbative BPS
states exactly, and show that it differs from that of the corresponding black
holes. We comment on the implication of our results to the black hole
microstate program, UV/IR mixing in Little String Theory, string
thermodynamics, the string/black hole transition, and other issues.Comment: 53 pages, 3 figure
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