By 2020 the LHC Run III will be about to start or will have just started, and it will be a crucial time to prepare theory predictions for the upcoming Run, as well as to get ready for the High-Luminosity LHC (HL-LHC) physics program, which will bring key measurements of the Higgs sector of the Standard Model and push the search for new physics, including dark matter, to yet higher masses and weaker interactions. Thanks to the detector upgrades and the increased luminosity, LHC measurements will achieve an unprecedented level of precision after 2020. For many new physics models, e.g. those whose new particles are beyond the LHC's immediate mass reach, the most immediate path to discovery will be to identify small modifications in the way known particles interact with each other. Because of the complicated environment in hadronic collisions, it is very challenging to pin down such effects. In order to fully exploit the potential of the LHC and the HL-LHC, it is imperative to make predictions at the level of accuracy that matches or even exceeds that of the upcoming measurements. A substantial part of current research on QCD and electroweak (EW) physics at colliders focusses on the following interconnected topics: the formal calculation of amplitudes and the required integrals, their use in fixed-order calculations of observables, and merging of fixed-order calculations to all-order results, either analytic resummations or parton-shower simulations.

This workshop aims to bring together at MIAPP the world leading experts in these topics and to address several key issues paramount to the future development of collider phenomenology.