A formula for the partition function of the beta-gamma system on the   cone pure spinors
  In this note, we propose a closed formula for the partition function $Z(t,q)$ of the $\beta\gamma$ system on the cone of pure spinors. We give the answer in terms of theta functions, $q$-Pochhammer symbols and Eisenstein series. 
M.V. Movshev
hep-th math.QA