Physics is a subject that can only thrive when there is strong interplay between theory and experiment. New theoretical ideas lead to predictions that can be tested experimentally, and new experimental findings challenge theorists to produce better ideas. Phenomenolgy is research on this boundary between theory and experiment. It is concerned with identifying interesting physical observables, making theoretical predictions for them and then confronting experimental data gathered at the major international laboratories. The main aim is to find evidence for new physics and to develop new theories that describe the Universe at a more fundamental level than our current theories can. Close collaboration with our experimental colleagues is a vital aspect of our work.

The last thirty years have seen the spectacular success of the Standard Model (SM) gauge quantum field theory of electromagnetic, weak and strong interactions. The high-energy accelerator programme at LEP, HERA and the TEVATRON have confirmed the validity of the SM, however, there are still important elements of the SM which lack either experimental observation or a well-established theoretical basis. The main missing element is the Higgs boson, whose existence is ultimately related to the understanding of the origin of the mass of all other particles. Existing precision electroweak observables show excellent consistency with the SM and constrain the mass of the Higgs boson significantly. Even if the Higgs boson is found, the SM is far from complete and the electroweak symmetry breaking mechanism, which is a fundamental element in the theoretical construction of the SM, is not yet well understood. It seems certain that more fundamental theories remain to be discovered.

It is convenient to define the following eight broad overlapping categories of research that cover the whole range of phenomenology at the IPPP. In many cases, research projects will fall into more than one of these categories.

Lattice phenomenology is an important strand of modern particle physics research whose primary aim is to increase the predictive power of the Standard Model of elementary particle interactions through numerical simulation of Quantum Chromodynamics (QCD) but is not studied at the IPPP.