Theory for muon-electron scattering @ 10 ppm - A report of the MUonE theory initiative P. Banerjee, C. M. Carloni Calame, M. Chiesa, S. Di Vita, T. Engel, M. Fael, S. Laporta, P. Mastrolia, G. Montagna, O. Nicrosini et al. (10 more) Eur. Phys. J. C, 80 6 (2020) 591 Published online: 29 June 2020 DOI: 10.1140/epjc/s10052-020-8138-9