The universal fibration with fibre $X$ in rational homotopy theory

Abstract

Let $X$ be a simply connected space with finite-dimensional rational homotopy groups. Let $p_\infty \colon UE \to \mathrm{Baut}_1(X)$ be the universal fibration of simply connected spaces with fibre $X$. We give a DG Lie model for the evaluation map $ \omega \colon \mathrm{aut}_1(\mathrm{Baut}_1(X_{\mathbb Q})) \to \mathrm{Baut}_1(X_{\mathbb Q})$ expressed in terms of derivations of the relative Sullivan model of $p_\infty$. We deduce formulas for the rational Gottlieb group and for the evaluation subgroups of the classifying space $\mathrm{Baut}_1(X_{\mathbb Q})$ as a consequence. We also prove that ${\mathbb C} P^n_{\mathbb Q}$ cannot be realized as $\mathrm{Baut}_1(X_{\mathbb Q})$ for $n \leq 4$ and $X$ with finite-dimensional rational homotopy groups.