Recommended Accelerator follow-up R&D: Milestone M2.6

This milestone documents the gaps between the results of the particle collider conceptual design study and the level of detail required to enter a project construction preparatory phase. This document establishes a portfolio of suggested R&D topics related to the domain of particle collider design and associated technologies that need to be addressed with high priority in a follow-up project in order to come to a consistent and coherent design on which a project construction preparation can be based.