Superconformal indices of three-dimensional theories related by mirror symmetry
C. Krattenthaler, V. P. Spiridonov, G. S. Vartanov
TL;DR
The paper establishes analytic proofs of the equality of superconformal indices for mirror-symmetric 3d $\mathcal{N}=2$ theories with abelian gauge groups, starting from the $N_f=1$ case and extending to arbitrary $N_f$. It employs $q$-hypergeometric identities, including Ramanujan summation and Heine transformations, to transform and equate electric and magnetic index expressions that factor into monopole sums and gauge integrals. A key feature is the treatment of the general $R$-charge parameter $h$ (via $a=q^{1-h}$) and the inclusion of the $U(1)_J$ symmetry, with results that hold beyond specific physical choices of $h$. The work reveals a structured, factorized kernel in 3d SCIs and points toward deeper connections with 4d elliptic hypergeometric integrals, while highlighting open questions about non-abelian generalizations and a full geometric interpretation of monopole contributions. Overall, it advances analytical understanding of 3d mirror symmetry through exact index equivalences grounded in $q$-special functions.
Abstract
Recently, Kim and Imamura and Yokoyama derived an exact formula for superconformal indices in three-dimensional field theories. Using their results, we prove analytically the equality of superconformal indices in some U(1)-gauge group theories related by the mirror symmetry. The proofs are based on the well known identities of the theory of $q$-special functions. We also suggest the general index formula taking into account the $U(1)_J$ global symmetry present for abelian theories.
