On the Distribution of Prime Squares and Its Applications
The paper studies the sequence of prime squares from three angles. The first is an exceptional-set problem of Goldbach type for representations n=a^2+b^2+p^2. The second is pointwise ergodic theory for averages along prime squares at or near L^1. The third is improving and sparse inequalities for the corresponding discrete averages.
Circle-method estimates for quadratic exponential sums over primes are combined with Landau–Page treatment of exceptional characters and a high–low decomposition. This decomposition yields fixed-scale improving inequalities, and maximal ℓ^2 estimates plus a stopping-time iteration upgrade them to sparse bounds. LaVictoire's criterion, together with Poisson spacing of quadratic residues (Granville–Kurlberg), gives L^1 divergence. A Lean 4 development accompanying the paper was produced with ChatGPT assistance.
For every A>0, all but O_A(X(log X)^{-A}) integers n<X with n≡11 (mod 24) are of the form a^2+b^2+p^2, with p and a^2+b^2+1 prime and (a,b)=1. Prime-square ergodic averages are persistently universally L^1-bad but converge almost everywhere for an explicit Orlicz class near L^1. Endpoint improving and sparse bounds are proved with an explicit Orlicz loss.
