The CERN theory community mourns the loss of André Petermann, one of the first members of the Theory Division, who passed away last August in his 89th year. He pioneered, together with his advisor Stueckelberg, the renormalization group, one of the fundamental ideas in quantum field theory that underlies the modern theory of phase transitions as well as asymptotic freedom and the quest for unification of all the particle interactions.

André was among the very first staff members of CERN, which at the beginning was a small group of theorists at the Niels Bohr Institute in Copenhagen, headed by Bohr himself.  When the group moved to Geneva, they first occupied a set of barracks in Cointrin, next to the airport, before moving to the University of Geneva, and then finally settling on the Meyrin site. André was our last direct contact with our nomadic origins.

The importance of André’s early work on the renormalization group was recognized by Kenneth Wilson who, when he was awarded the Nobel Physics Prize for his work applying the renormalization group to critical phenomena, kindly acknowledged a congratulatory letter from André by paying tribute to his joint paper with Stueckelberg for initiating the whole renormalization group effort.

Another of André’s important contributions to field theory and particle physics was his pioneering calculation of the next-to-leading order correction to the anomalous magnetic moment of the muon. This was key to the interpretation of the famous CERN experimental measurement of this quantity, and is still a reference for today when the theoretical interpretation of this quantity is much debated.

André’s scientific interests ranged far and wide, extending in later years to include grand unification and the study of superstring compactifications. Long after his formal retirement, he would often be encountered browsing  preprints late at night, and many of us recall with fondness long telephone calls from André, quizzing us about some recent publication.

André was a very special person, somebody with great purity of vision, breadth of interest and integrity. He had a deep understanding of physics and mathematics, and was an exceptional man whose manifold contributions to physics will live on.

CERN-TH is grateful to him: we feel deeply his passing.

Luis Alvarez-Gaumé, Ignatios Antoniadis, John Ellis & André Martin.