  We summarize the Fermilab Accelerator Complex Evolution (ACE) Science
Workshop, held on June 14-15, 2023. The workshop presented the strategy for the
ACE program in two phases: ACE Main Injector Ramp and Target (MIRT) upgrade and
ACE Booster Replacement (BR) upgrade. Four plenary sessions covered the primary
experimental physics thrusts: Muon Collider, Neutrinos, Charged Lepton Flavor
Violation, and Dark Sectors. Additional physics and technology ideas were
presented from the community that could expand or augment the ACE science
program. Given the physics framing, a parallel session at the workshop was
dedicated to discussing priorities for accelerator R\&D. Finally, physics
discussion sessions concluded the workshop where experts from the different
experimental physics thrusts were brought together to begin understanding the
synergies between the different physics drivers and technologies.
  In December of 2023, the P5 report was released setting the physics
priorities for the field in the next decade and beyond, and identified ACE as
an important component of the future US accelerator-based program. Given the
presentations and discussions at the ACE Science Workshop and the findings of
the P5 report, we lay out the topics for study to determine the physics
priorities and design goals of the Fermilab ACE project in the near-term.
