Proves the Scaling Closure Theorem: d_R = (d*nu + 2*eta)/(d*nu + eta) from five structural assumptions (A1-A5) about the microscopic Fisher manifold at criticality. A1 (Ricci decomposition) and A2 (Z_2 fusion) and A4 (eigenvalue anisotropy) are proved as theorems. A3 (diagonal block cancellation) at 99.95%+ and A5 (triangle non-cancellation) at 99.9%+. Universality verified across 8 CFT classes including 2D Ising, Potts q=3,4, 3D Ising/XY/Heisenberg, BKT, and Gaussian. Companion proof paper for the Prediction Letter (arXiv:2603.07651).
We study the scalar curvature of the Fisher information metric on the microscopic coupling-parameter manifold of lattice spin models at criticality. For a
d-dimensional lattice with periodic boundary conditions and
n=Ld sites, the Fisher manifold has
m=d⋅n dimensions (one per bond), and we find
∣R(Jc)∣∼ndR with
dR=(dν+2η)/(dν+η), where
ν and
η are the correlation-length and anomalous-dimension critical exponents. For 2D Ising (
ν=1,
η=1/4), this predicts
dR=10/9, confirmed by exact transfer-matrix computations (
L=6--
9:
dR=1.1115±0.0002) and multi-seed MCMC through
L=24. For 3D Ising (
ν=0.630,
η=0.0363), the prediction
dR=1.019 is consistent with MCMC on
L3 tori up to
L=10 (power-law fit:
dR=1.040). For 2D Potts
q=3 (predicted
33/29≈1.138), FFT-MCMC through
L=40 shows
deff oscillating non-monotonically around
∼1.20, consistent with
O(1/(lnL)2) logarithmic corrections. For
q=4 (predicted
22/19), effective exponents oscillate with strong logarithmic corrections. The Ricci decomposition identity
R3=−R1/2,
R4=−R2/2 holds to 5--6 digits for all models. This exponent is distinct from Ruppeiner thermodynamic curvature and reflects the collective geometry of the growing Fisher manifold. We provide falsification criteria and predictions for additional universality classes.
The Ising model in two dimensions with the special boundary conditions of Brascamp and Kunz is analyzed. Leading and subdominant scaling behavior of the Fisher zeros are determined exactly. The exact finite-size scaling, with corrections, of the specific heat is determined both at critical and effective critical (pseudocritical) points. The shift exponents associated with the scaling of these effective critical points are not the same as the inverse correlation length critical exponent. All corrections to scaling are analytic.