The Virasoro Bootstrap: from the $c\sim1$ desert to coupled Potts

Abstract

We develop a numerical conformal bootstrap for two-dimensional CFTs with $c>1$ based on Virasoro conformal blocks, computed with Zamolodchikov's recursion and optimal polynomial interpolation. As a first test we isolate an island around three decoupled Ising models. We then consider three 3-state Potts models coupled through their energy operators, a candidate irrational CFT. Mixed correlators isolate the decoupled theory in an island, and different gap assumptions, motivated by perturbation theory, yield a peninsula that contains the coupled fixed point but not the decoupled one. Finally, we explore the standard single-correlator bound on the lowest-dimension scalar primary in the OPE of two identical scalars. We find that for central charges just above $c=1$ the bound collapses over a wide range of external dimensions. This excludes any theory whose lightest scalar is absent from its own OPE and lies in this range, and supports the conjecture that no compact CFT exists in this region. We explain several features of these bounds analytically.