Phenomenology from Lattice QCD and collider physics

Lead Research Organisation: University of Glasgow
Department Name: School of Physics and Astronomy

Abstract

The Glasgow theory group has a strong reputation in studies of the subatomic world, and pushing forward 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 or other 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. Glasgow continues to lead progress and here we propose calculations that will predict more accurately how hadrons decay from one type to another via the weak force. The comparison with experiment will then allow us to push down uncertainties in the parameters of the weak force that allow for violations of symmetry between matter and antimatter. We also plan to calculate accurately the tiny effect of the strong force on the magnetic moment of the muon ahead of a new experimental determination of this quantity that aims to find out for sure whether it agrees with the Standard model or not.

The Glasgow team will also investigate theories that go beyond the Standard Model and test them with LHC data. The recent discovery of the Higgs boson is the last piece of the Standard Model and is a triumph for both theoretical and experimental particle physics. However, we must ensure that the particle discovered is indeed the Higgs boson of the Standard Model, so we must undertake a comprehensive programme to measure its properties. New physics may show up by subtly modifying these properties and we will devise ways of looking for these effects. The LHC will also produce large numbers of top quarks for the first time, and since the top quark is the heaviest particle in the Standard Model, one expects its properties also to be affected by new physics. So, as for the Higgs boson, we will also investigate top quark properties using a general model independent framework. We will then examine specific new physics models, such as theories of Grand Unification, which unify the three forces together as one single force. We will determine how these exciting and fundamental theories affect the particle properties described above and thereby confront them with LHC observations. Experimental studies on the Higgs boson and top quarks are being led by the Glasgow ATLAS group and we will coordinate with them to uncover the fundamental truths of the universe.

The next few years will be a very exciting time for theoretical particle physics and Glasgow aims to be at the forefront of this work.

Planned Impact

Our research has impact in three different ways:

Firstly there is 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 areas such as computing science. We will investigate these possibilities, building on recent success where techniques to handle gravity were used for the description of novel optical materials.

Secondly there is the use of our research to encourage young people to enter physics degrees, or to equip graduates for successful entry into the private sector.

* We will continue to inspire young people by presenting our research results during the annual Glasgow Particle Physics masterclass, attended by Scottish schoolchildren. 130 pupils attend each year, with 65% subsequently applying to study with us.

* We will make a video on particle physics for use by schoolteachers as part of the new Scottish curriculum for excellence at Higher and Advanced Higher level.

* We will continue to engage project students at masters level in our research, leading to enhanced training in computational and analytical skills, as well as academic publications.

Thirdly there is the use of our research to foster scientific awareness amongst the public.

* We will continue to engage, along with our PhD students, in a wide range of outreach programmes. These include talks in schools and community centres and at organised events such as the Glasgow Science Festival, now one of the largest in the UK, European Researchers Night and Pint of Science.

* We will also 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.

Publications


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