The eminent theoretical physicist Roger Julian Noel Phillips died peacefully on 4 September 2020, aged 89, at his home in Abingdon, UK. Roger was educated at Trinity College, Cambridge, where he received his PhD in 1955. His thesis advisor was Paul Dirac. Roger transferred from the Harwell theory group to the Rutherford Appleton Laboratory (RAL) in 1962 where he led the theoretical high-energy physics group to international prominence. He also held visiting appointments at CERN, Berkeley, Madison and Riverside.
Roger was a giant in particle physics phenomenology and his book “Collider Physics” (Addison-Wesley, 1987), co-authored with his longstanding collaborator Vernon Barger, remains a classic. In 1990 Roger was awarded the Ernest Rutherford Prize & medal of the UK Institute of Physics. To experimenters, he was one of the rocks upon whom the UK high-energy physics community was built. To theorists, he was renowned for his deep understanding of particle-physics models. A career-long collaboration across the Atlantic with Barger ensued from their sharing an office at CERN in 1967. Their initial focus was the Regge-pole model to describe high-energy scattering of hadrons. Subsequently they inferred the momentum distribution of the light quarks and gluons from deep-inelastic scattering data and made studies to identify the charm-quark signal in a Fermilab neutrino experiment.
To experimenters, he was one of the rocks upon whom the UK high-energy physics community was built
In 1980, Phillips and collaborators discovered the resonance in neutrino oscillations when neutrinos propagate long distances through matter. This work is the basis of the ongoing Fermilab long-baseline neutrino program that will make precision determinations of neutrino masses and mixing. From 1983, Phillips and his collaborators developed pioneering strategies in collider physics for finding the W boson, the top quark, the Higgs boson and searches for physics beyond the Standard Model. In an influential 1990 publication, Phillips, Hewett and Barger showed that the decay of a b-quark to an s-quark and a photon is a highly sensitive probe of a charged Higgs boson through its one-loop virtual contribution.
After retiring in 1997, Roger maintained an active interest in particle physics. He struggled with Parkinson’s disease in recent years but continued to live with determination, wit and cheer. He joked that his Parkinson’s tremor made his mouse and keyboard run wild: “I know that an infinite number of random monkeys can eventually write Shakespeare, but I can’t wait that long!” One of his very last whispers to his son David was: “There are symmetries in mathematics which are like aspects of dreaming”. He did great things with his brain when he was alive that will continue as he donated his to the Parkinson’s UK Brain Bank.
Roger was highly respected for his intellectual brilliance, physics leadership and immense integrity, but also for his modesty and generosity in going out of his way to help others. He was a delight to work with and an inspiration to all who knew him. He is missed by his many friends around the world.