# 2012 Dirac medal

Professor Graham Garland Ross, Rudolf Peierls Centre for Theoretical Physics, University of Oxford.

For his theoretical work in developing both the Standard Model of fundamental particles and forces and theories beyond the Standard Model that have led to many new insights into the origins and nature of the universe.

In a research career in theoretical particle physics spanning 40 years, Graham Ross has consistently worked at the very frontiers of the subject and made a large number of truly seminal contributions.

In the early part of his career he was associated with a number of key developments in the establishment of the Standard Model of particle and forces, particularly the development of the strong interaction field theory Quantum Chromodynamics.

His landmark 1977 paper with Ellis and Gaillard paved the way for the experimental discovery of the gluon, the strong interaction force-carrying particle, and later work led to a deeper understanding of how a polarised nucleon’s spin is shared among its parton constituents.

For most of his career, however, Ross has been associated with key theoretical developments in the search for a more fundamental ‘Beyond the Standard Model’ theory.

His particular forte is establishing the phenomenological implications of such theories, and using experimental measurements as a guide to constructing a ‘theory of everything’.

He was one of the pioneers of supersymmetry theory and phenomenology, exploring the implications for grand unification, the supersymmetric particle mass spectrum and cosmology.

He was among the first to develop and explore the implications of supersymmetric models with broken R-parity.

He has shown how realistic low-energy theories can emerge from string theories in higher dimensions and, following the experimental discovery that neutrinos have non-zero mass, he has developed fundamental theories of neutrino mass and mixing parameters.

In particular, he and his collaborators were among the first to show how neutrino ‘bi-tri-maximal’ mixing arises naturally in theories with family symmetry.