SAC-Copula: Quality-Preserving Watermarking for Diffusion Language Models via Smooth Correlated Gumbel Fields
SAC-Copula is proposed, a quality-preserving watermarking method for DLMs based on smooth, locally correlated Gumbel perturbation fields constructed via a Gaussian copula that substantially improves PPL tail stability over the i.i.d. Gumbel baseline while maintaining strong low-FPR detectability and competitive overall...