Falling stars: a fall-decorated rational shuffle theorem

In this paper, we formulate a rational analog of the fall Delta theorem and the Delta square conjecture. We find a new dinv statistic on fall-decorated paths on a (m+k) × (n+k) rectangle that simultaneously extends the previously known dinv statistics on decorated square objects and non-decorated rectangular objects. We prove a symmetric function formula for the $q,t$-generating function of fall-decorated rectangular Dyck paths as a skewing operator applied to em,n+km and, conditionally on the rectangular paths conjecture, an analog formula for fall-decorated rectangular paths.