We produce infinitely many distinct irreducible smooth 4–manifolds homeomorphic to \(\#_{2m+1}({\mathbb{C}\mathbb{P}} ^{2}\,\#\, \overline{\mathbb{C}\mathbb{P}} ^{2})\) and \(\#_{2n+1} (S^2 \times S^2)\) , respectively, for each \(m \ge 4\) and \(n \ge 5\) . These provide the smallest exotic closed simply connected 4–manifolds with signature zero known to date, and in each one of these homeomorphism classes, we get minimal symplectic 4–manifolds. Our novel exotic 4–manifolds are derived from fairly special small Lefschetz fibrations we build via positive factorizations in the mapping class group, with spin and non-spin monodromies.
