Zimmermann, F. Zanetti, M. JACoW Publishing Geneva, Switzerland 978-3-95450-216-5 10.18429/JACoW-eeFACT2018-MOYBA04 English 41-45 MOYBA04 collider factory positron target emittance Contribution to a conference proceedings 2019 2019-04 https://doi.org/10.18429/JACoW-eeFACT2018-MOYBA04 http://jacow.org/eefact2018/papers/moyba04.pdf Several novel concepts could help the muon collider become a reality. These concepts include parametric ionization cooling, low-emittance muon production by positron annihilation (LEMMA scheme), production of low-emittance muon or positron beams using the Gamma Factory concept, and strategies to upgrade large accelerator complexes, like the LHC or the FCC, into a highest-energy muon collider. The muon collider workshop organized by ARIES APEC at Padua in July 2018 gathered the international community in order to review the recent progress and to formulate a common R\&D strategy. Several important conclusions and recommendations were drawn.