Tight colorful no-dimensional Tverberg theorem

Abstract: We prove a tight colorful dimension-free Tverberg theorem asserting that for any pairwise disjoint $k$-point sets $Q_1,\dots, Q_r$ in the Euclidean space, there are a partition of the union $Q_1\cup\dots \cup Q_r$ into $r$-point subsets $P_1,\dots, P_k$ and a ball of radius $$ \frac{\mathrm{max}{1\leq i\leq k}\mathrm{diam} P_i}{\sqrt{2r}} $$ such that each $P_i$ shares exactly one point with each $Q_j$ and the ball intersects the convex hulls of $P_i$. Additionally, we prove versions of this theorem in $\ell{\infty}$ and hyperbolic space.