Theoretical physics has been pivotal in shaping and consolidating the Standard Model and is now crucial for formulating possible scenarios for future discoveries. It directly addresses the key scientific questions in this area and provides many of the scientific justifications for designing and constructing new experimental facilities.
The UK has leadership in all aspects of Formal Theory and is considered to rank second only to the US in terms of scientific output. The UK continues to make important contributions to quantum field theory, string theory, SUSY and black holes. Examples of particular strengths are the study of non-perturbative dualities and solitons in quantum field theory, the related topic of branes (higher dimensional localised objects) in string theory, supergravity and particle cosmology (especially the evolution of the Universe just after the big bang).
There has been a substantial upsurge in UK phenomenology since the turn of the millennium. It is now firmly established as internationally leading and adds significant value and impact to the experimental programme. The Institute for Particle Physics Phenomenology has been a particularly successful initiative in this field, together with several other groups which also contribute to cutting-edge research.
Over the last 20 years lattice field theory calculations in the UK have been led by the UKQCD consortium which has achieved major advances in the understanding of observations from worldwide particle physics experiments. In particular, it has achieved highly visible results from full dynamical simulations including the three lightest quarks using the DiRAC supercomputer.