Exotic 4 -Manifolds from Genus-4 Lefschetz Fibrations

In this paper, we study minimal simply connected 4-manifolds with b_2^+=3 which admit genus-4 Lefschetz fibrations over the 2-sphere. We first explicitly construct a genus-4 Lefschetz fibration over the 2-sphere using the monodromy of generalized Matsumoto fibration of genus 3 and the monodromy of the smallest genus-2 fibration given by Baykur and Korkmaz. We then construct two genus-4 Lefschetz fibrations over the 2-sphere that are exotic minimal symplectic 4-manifolds belonging to the homeomorphism classes of 3CP^2#15¯(CP^2 ) and 3CP^2#14¯(CP^2 ) by performing the fiber sum operation and then lantern substitution.