Gamma conjecture II and explicit Stokes data for a quadric projective bundle

Abstract

We study the connection problem for the quantum differential equation of the Fano fourfold $X=\PP_{Q^3}(\OO\oplus\OO(1))$. The problem is to identify its canonical asymptotic solutions with exceptional objects and compute the associated Stokes data. We use exact Mellin--Bessel integral representations and uniform vector asymptotics on sectors wider than $π$, followed by analytic continuation that preserves the Gamma framing. Cohomological chiral symmetry and mutations of exceptional collections put all eight sections at a common phase. This proves Gamma conjecture II for $X$ and determines a full exceptional collection and its Stokes and central connection matrices at the unit Novikov point and a specified admissible phase. The chiral symmetry also gives a flat symmetric bilinear pairing, an orthogonality identity for the Stokes matrix, and an integral unipotent square root of the monodromy matrix for a full turn. We obtain explicit formulas for the connection data at the opposite phase; on the Gamma lattice, the half-turn acts by tensoring with a square root of the anticanonical bundle. The same spinor integral transform constructs two canonical Gamma sections for $\PP_{Q^{2m+1}}(\OO\oplus\OO(1))$, $m\geq1$, at positive parameters with distinct spectrum. Their sectors have opening greater than $π$, and their leading constants are independent of the dimension.