The stochastic telegraph equation limit of the stochastic higher spin six vertex model

In this paper, we prove that the stochastic telegraph equation arises as a scaling limit of the stochastic higher spin six vertex (SHS6V) model with general spin $I\mathrm{/}2,J\mathrm{/}2$. This extends results of Borodin and Gorin which focused on the $I=J=1$ six vertex case and demonstrates the universality of the stochastic telegraph equation in this context. We also provide a functional extension of the central limit theorem obtained in [Borodin and Gorin 2019, Theorem 6.1]. The main idea is to generalize the four point relation established in [Borodin and Gorin 2019, Theorem 3.1], using fusion.