Jizhou Guo
Let $λ(n)=(-1)^{Ω(n)}$ be the Liouville function. For every fixed $0 < η< 1$ and $C>0$, we prove that all sufficiently large $x$ admit $\mathcal E_{x,η}\subseteq[1,\exp((\log x)^η)]$, $|\mathcal E_{x,η}|\ll_{η,C}\exp((\log x)^η)(\log x)^{-C}$, such that, for some $c_η>0$, $\max_{\substack{h\le\exp((\log x)^η)\\h\notin\mathcal E_{x,η}}}\left|\sum_{n\le x}\frac{λ(n)λ(n+h)}{n}\right|\ll_η(\log x)^{1-c_η}$. The set is generated by one possible Landau--Page conductor, contains at most one prime, and is empty when no such exceptional character exists. We also obtain an all-shifts power-logarithmic saving for $h\le(\log x)^A$ for every fixed $A>0$. A separate harmonic-multiplier argument gives, for every fixed $1 < p < \infty$ and every $1$-bounded sequence $b$, $\frac1H\sum_{L1/3$. Consequently, for arbitrary fixed $\varepsilon,C>0$, outside $O_{θ,\varepsilon,C}(H(\log x)^{-C})$ shifts all terminal correlations are at most $(\log x)^\varepsilon$. For every $H\ge10$ we also prove quantitative first- and second-moment bounds, yielding $o(\log x)$ for almost every $h\le H(x)$ whenever $H(x)\to\infty$.