<u>The Ideas of Particle Physics : four decades past and the next</u>

Over the last four decades, many outstanding questions in particle physics have been answered, leading to the Standard Model and its spectacular confirmation with the discovery of the Higgs boson and a wide range of experiments. But our increasingly sophisticated level of understanding has led to even deeper questions. The recently confirmed phenomenon of neutrino oscillations (and so neutrino mass) is definitely beyond its scope. Also, cosmological observations now indicate that as much as 96 percent of the Universe is made up of unknown sources of ‘dark matter’ and ‘dark energy’ which have yet to be accommodated within the SM.

This talk presents the story of the Ideas of Particle Physics from its first edition in 1984 and reviews the progress achieved in the ten key challenges then identified. The talk then identifies ten key challenges described in the fourth edition for the next four decades.

(Ref: The ideas of Particle Physics, J.E. Dodd, Cambridge University Press, first edition1984. Fourth edition with B.M. Gripaios 2020)