Spectrum of CHL dyons from genus-two partition function

  title={Spectrum of CHL dyons from genus-two partition function},
  author={Atish Dabholkar and Davide Gaiotto},
  journal={Journal of High Energy Physics},
We compute the genus-two chiral partition function of the left-moving heterotic string for a 2 CHL orbifold. The required twisted determinants can be evaluated explicitly in terms of the untwisted determinants and theta functions using orbifold techniques. The dependence on Prym periods cancels neatly once summation over odd charges is properly taken into account. The resulting partition function is a Siegel modular form of level two and precisely equals recently proposed dyon partition… 

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