Perverse filtrations, Chern filtrations, and refined BPS invariants for local [formula omitted

Abstract

We explore connections between three structures associated with the cohomology of the moduli of 1-dimensional stable sheaves on P2: perverse filtrations, tautological classes, and refined BPS invariants for local P2. We formulate the P=C conjecture identifying the perverse filtration with the Chern filtration for the free part of the cohomology. This can be viewed as an analog of de Cataldo–Hausel–Migliorini's P=W conjecture for Hitchin systems. Our conjecture is compatible with the enumerative invariants of local P2 calculated by refined Pandharipande–Thomas theory or Nekrasov partition functions. It provides a cohomological lift of a conjectural product formula of the asymptotic refined BPS invariants. We prove the P=C conjecture for degrees ≤4.