Lattice investigations of strongly Interacting theories in the Standard Model and beyond.

The research project of the theoretical particle physics group at the University of Plymouth focuses on key issues of modern particle physics. Two strands of research are pursued. In the first strand of research, the group takes part in the race to decrease the theoretical uncertainty on a quantity measured experimentally to an extraordinary

precision called the anomalous magnetic moment of the muon. An on-going current experiment that measures the small magnetic moment of the muon, a heavier cousin of the electron, aims at reducing further the experimental errors. Our theoretical calculations will allow further tests of the theory that describes all phenomena at the level

of fundamental particles, called the Standard Model of particle physics. A statistically significant larger difference between the experimental and theoretical results would give strong hints to what lies beyond the Standard Model and it would be a major discovery. The theoretical calculation itself represents a major computational and

theoretical challenge, due to the large number of contributions to the muon anomalous moment, and due to the target high accuracy required to match the experimental precision. The second strand of research focuses on exploring theories that can be used to address the Standard Model's shortcomings. Two main

directions are considered. First, the project will explore the intriguing possibility that the Higgs boson - discovered in 2012 - could be a composite particle made of something else. The so called Composite Higgs models use mechanisms similar to the one that is responsible for the confinement of the quarks inside a proton. The proton is the simplest example of

a well-known particle, which is not fundamental, but composite. Another direction is to explore and make predictions to test models that could explain the 85\% of the matter in the Universe that is not described by the current theory of the interactions of elementary particles. Over the years, a lot of experimental evidence has been gathered that support the

existence of the elusive "Dark Matter". Recent observations, notably of the "Bullet Cluster" which consists of two colliding galaxies suggest that Dark Matter interacts strongly with itself. Theories that feature such a strong interaction share similarities with the theory that describes the interaction of quarks and lead to the formation of

the proton as a bound state, and with the theories that are candidates to feature a composite Higgs boson. The calculations performed will further constrain well motivated models and therefore contribute to answer the question : "What are the fundamental particles?" and "What is the nature of dark matter?".