The Cosmological Grassmannian

In this talk, I will introduce the orthogonal Grassmannian as a novel kinematic space for describing correlators of massless spinning fields in de Sitter space. By automatically encoding the constraints of conformal symmetry and current conservation, the formalism drastically simplifies these correlators. At three points, the correlators are fixed by little group covariance. At four points, unitarity enforces the same factorization properties as in scattering amplitudes, allowing us to easily bootstrap the answers. The resulting expressions are astonishingly simple and reveal a close connection to the corresponding scattering amplitudes. Interestingly, the orthogonal Grassmannian is deeply connected to twistor space, which naturally encodes the same constraints on correlators. Time permitting, I will make this connection explicit and discuss how it can be leveraged to compute the exchange of massive spinning particles within the Grassmannian formalism.