Particle Theory at the Higgs Centre

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There are two types of fundamental forces in Nature: those responsible for particle interactions at subatomic scales and those responsible for the large scale structure of the universe. The former is described by Quantum Field Theories (QFT) such as the Standard Model(SM). Currently, our understanding of Nature at the most fundamentallevel is at the crossroads. Last year, the LHC at CERN collided protons at higher energies than ever before, and observed sufficient collisions to find a significant excess at 125 GeV,consistent with the Higgs boson of the SM. Over the coming years it should becomeclear whether this is indeed a SM Higgs, responsible for generating masses for vector bosons, leptons and quarks, or whether it is something different. It should also become clearer whether there is more physics at the TeV scale, or whether this is it. In either event, it is clear that this will be a transformative period in fundamental physics, making the next few years the most exciting time for a generation or more. Our programme of research at the Higgs Centre for Theoretical Physics in Edinburgh is designed to be at the forefront of these new discoveries: indeed Peter Higgs himself is Emeritus Professor here. Specifically, we provide theoretical calculations, using pen and paper, and the most powerful supercomputers, of both the huge number of background processes to be seen at LHC due to known physics, and the tiny signalsexpected in various models of new physics, in order to discriminate between signal and background, and thus maximise the discovery potential of the LHC. In parallel, we will attempt to understand the more complete picture of all the forces of Nature that may begin to emerge. The fundamental force responsible for large scale structure is described Einstein's General Theory of Relativity (GR). During the last three decades, string theory has emerged as a conceptually rich theoretical framework reconciling both GR and QFT. The low-energy limit of String Theory is supergravity (SUGRA), a nontrivial extension of GR in which the universe is described by a spacetime with additional geometric data. Members of the group have pioneered approaches to deriving observablecosmological consequences of String Theory, to studying how the geometrical notions on which GR is predicated change at very small ("stringy") distance scales, and the systematic classification of SUGRA backgrounds. The group is also engaged in using these theories to improve calculations in existing field theories. In summary, our research will impinge on both theoretical and computational aspects relevant to probing the phenomenology of incoming LHC data, and will also encompass a wide range of topics in QFT and gravitational aspects of String Theory, impinging on cosmology, particle physics and on the very nature of String Theory itself.