MadStree: automated evaluation of tree-level de Sitter correlators

We first derived the formulae of recursive reduction and dlog-form differential equations for arbitrary tree-level cosmological correlator, taking the external relations of massless bulk propagators into consideration. The differential equations could be systematically solved and provide the efficient evaluation of them. We have implemented this methodology as a user-friendly Mathematica package MadStree for computing arbitrary tree-level cosmological correlators.