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?".