Phenomenology from lattice QCD and collider physics

The Glasgow theory group has a strong reputation in studies of the subatomic world, innovating to extend our understanding of how it works. This is aimed at uncovering the fundamental constituents of matter and the nature of the interactions that operate between them. There are two approaches to this, and we will use both of them. One is to perform very accurate calculations within the theoretical framework of the Standard Model that we believe correctly describes the particles that we have seen so far and the strong, weak and electromagnetic forces of Nature. Discrepancies between these accurate calculations and what is seen in experiments will then point the way to a deeper theory that describes fundamental particle physics more completely. The second method is concerned with what we might see at CERN's Large Hadron Collider if one of the suggested deeper theories is correct. We must make sure that we optimise the analysis of the experiments there to learn as much as possible.

Accurate calculations in the Standard Model have foundered in the past on the difficult problem of how to handle the strong force. This force is important inside particles that make up the atomic nucleus, the proton and neutron and a host of similar particles called hadrons produced in high energy collisions. The constituents of these particles are quarks, and they are trapped inside hadrons by the behaviour of the strong force. This 'confinement' of quarks makes calculations of the effect of the strong force on the physics of hadrons very challenging. It can be tackled, however, using the numerical technique of lattice QCD, which Glasgow has been instrumental in turning into a precision tool, and where we continue to lead progress. Here we will predict more accurately how hadrons containing b quarks decay via the weak force and we will reduce uncertainties on how neutrinos interact with protons and neutrons in the atomic nucleus. We will also improve accuracy on the tiny effect of the strong force on the magnetic moment of the muon. These calculations are aimed at improving analysis of experiments around the world (including at CERN), which aim to understand the violations of symmetry between matter and antimatter, how neutrinos behave and whether the value of the muon's magnetic moment reveals the presence of new particles.

The Glasgow team will also investigate theories that go beyond the Standard Model and confront them with LHC data. The recent discovery of the Higgs boson was the final piece of the Standard Model and is a triumph for both theoretical and experimental particle physics. However, there is strong evidence that the Standard Model needs to be embedded in a more fundamental theory of nature as there is no explanation for the over-abundance of matter compared to anti-matter or the presence of dark matter, both of which are firmly established by astrophysical observations. Theoretical insights suggest that the Higgs boson could be the harbinger of a more fundamental theory that will address these questions. New physics would then manifest itself in deviations of the Higgs boson's properties from the Standard Model expectation. We will undertake a comprehensive programme to determine its properties in the most accurate way by developing computer-based strategies that will reveal sensitivity where the traditional methods of the past are bound to fail. In parallel, we will also investigate the properties of the top quark, which are complementary tell-tale signs of new physics. We will compare our findings to new physics models like theories of Grand Unification, which unify the three forces to one single force while addressing the aforementioned shortcomings of the Standard model at the same time. We will determine if these exciting theories are consistent with LHC measurements and determine which steps to take next to uncover the fundamental truths of the universe.

Our research has impact in three different ways.

Firstly there is the impact on other academic areas:
* Our results in both lattice QCD and collider physics will feed directly into experimental physics analyses, assisted in some cases by direct collaboration with experimentalists. We expect significant impact of this kind during the three-year timescale of the grant and beyond.
* Elements of our work, particularly techniques that we develop, have applicability in other areas. We will extend links established with Glasgow optics, gravitational waves and quantum theory groups to push forward some of these ideas.

Secondly there is the use of our research to encourage young people to enter science degrees:
* We will continue to inspire young people through our particle physics masterclass.
* We plan to make a video on particle physics for use by Scottish teachers of the new Higher curriculum in physics.

Thirdly there is the use of our research to foster scientific awareness among the general public:
* We will continue to engage, along with our PhD students, in a wide range of outreach programmes. These include talks at events such as the Pint of Science Festival, and outreach activities around the successful book "Destination:Space".
* We will continue to engage with learned societies and funding agencies on advocacy and policy issues, particularly around Women in Physics where we have a strong track record.