European Strategy for Particle Physics

The European Strategy for Particle Physics is the cornerstone of Europe’s decision-making process for the long-term future of the field. Mandated by the CERN Council, it is formed through a broad consultation of the grass-roots particle physics community, it actively solicits the opinions of physicists from around the world, and it is developed in close coordination with similar processes in the US and Japan in order to ensure coordination between regions and optimal use of resources globally.

The European Strategy process was initiated by the CERN Council in 2005, resulting in a document being adopted by the Council in 2006. Unsurprisingly, this document placed the LHC at the top of Europe particle physics’ scientific priorities, with a significant luminosity upgrade already being mooted. A ramp-up of R&D into future accelerators also featured high on the priority list, followed by coordination with a potential International Linear Collider, and participation in a global neutrino programme. The original Strategy also foresaw increased collaboration with neighbouring fields such as astroparticle and nuclear physics, and it recognised the importance of complementary issues such as communications and technology transfer.

The original European Strategy prescribed regular updates to take into account the evolution of the field. The first of these was prepared in 2012 and adopted in 2013. By this time, the LHC had proved its capacity with the discovery of the long-sought Higgs boson, evidence for the Brout-Englert-Higgs mechanism through which fundamental particles acquire their mass.

Again, it came as no surprise that the LHC topped the list of scientific priorities for European particle physics, with the high-luminosity upgrade increasing in importance, and preparations for the post-LHC future taking shape. “Europe”, said the Strategy document, “needs to be in a position to propose an ambitious post-LHC accelerator project at CERN by the time of the next Strategy update.”

The remainder of the updated recommendations represented logical and evidence-based evolutions of those contained in the initial European Strategy. All have been, or are in the process of being, implemented.

As the second update of the European Strategy gets underway, the stakes are high. Europe, in collaboration with partners from around the world, is engaged in R&D projects for a range of ambitious post-LHC facilities under the CLIC and FCC umbrellas. It is time to check progress on these, matching their expected performance to physics needs. The discussions will be based on scientific evidence gleaned from the impressive results coming in from the LHC, as well as from technological and resourcing considerations.

In other areas of particle physics, much has changed since the last strategy update. Europe, through CERN, is now contributing fully to a globally-coordinated neutrino programme with experiments to be carried out in the USA and Japan. The International Linear Collider, which would be complementary to the LHC, remains on the table with a site having been identified in Japan and a decision on whether to go forward expected soon. There are ambitious plans to build a large collider in China. And at CERN, a study to investigate the potential for physics beyond colliders, maximising the potential for CERN’s unique accelerator complex, was launched in 2016. All of these factors will feed into the deliberations soon to get underway to update the European Strategy for Particle Physics.

The current update of the European Strategy was initiated by the CERN Council in December 2016 to be carried out between 2018 and 2020, a date deemed optimal for the major decisions that need to be taken for the future of particle physics in Europe. A call for input was made in March 2018, with dates being fixed for the key information gathering and drafting stages in August 2018.

Strategic planning in European particle physics is an open, inclusive and evidence-driven process. Follow the current strategy update as it evolves, and join us on the unfolding adventure of research at the frontier of knowledge.