Investigations in Quantum Chromodynamics and Physics Beyond the Standard Model

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

Abstract

The Glasgow theory group has a strong reputation in two different methods of studying the subatomic world, and pushing forward our understanding of how it works. In the first, we attempt very accurate calculations within the theoretical framework called the Standard Model that we believe correctly describes the particles that we see at high energy accelerators and their interactions, through 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 going beyond our existing framework to a deeper theory that describes fundamental particle physics more completely. The second method is concerned with what we might see at the new experiments associated with the Large Hadron Collider (LHC) (shortly to start running at CERN) if one or other of the suggested deeper theories is correct. We must make sure that we optimise the analysis of these experiments to learn as much as possible. Accurate calculations in the Standard Model often founder 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 made 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' makes calculations of the effects of the strong force on the hadrons we can see very hard. The only practical method is numerical simulation of the theory, and this is very challenging. Recently significant progress was made - we calculated the masses of lots of different hadrons accurately with answers that agreed with experiment for the first time. Glasgow played a big part in this and continues to lead progress, particularly with results for hadrons containing b and c quarks. These hold the key to the tests of the Standard Model described above both from current experiments and future ones at LHC. Experiments can measure, for example, the rate at b or c hadrons change into other hadrons by a reaction mediated by the weak force, akin to nuclear beta decay. With the precision calculations that the Glasgow team will now do in our numerical simulations we can make a comparison with experiment and pin down the parameters of the weak force that allow for violations of symmetry between matter and antimatter. This allows us to test the Standard Model very stringently. The Glasgow team will also investigate theories that go beyond the Standard Model, in particular theories that predict new particles that we might discover at the LHC. We expect to find at least the Higgs particle, which gives rise to the masses of other particles, and may even discover exotic new particles associated with theories such as supersymmetry or extra dimensions. We hope that discovering these particles and measuring their properties will lead to a unified theory of the fundamental forces. To achieve this goal requires both precision calculations and systematic investigations of new physics models, for which our expertise leaves us ideally placed. This allows us to make theoretical predictions for both the Standard Model and the new physics so that we can accurately compare them with results from our experimental colleagues working on the LHC. We also investigate additional signals and ways of improving existing methods for finding new physics. The next five years will be a very exciting time for theoretical particle physics and Glasgow aims to be at the forefront of this.

Publications

10 25 50
 
Description We have performed a number of ground-breaking computations of the properties of hadrons from the theory of the strong interaction along with studies of signals at the Large Hadron Collider that can be used to test the Standard model of particle physics.
Exploitation Route Our findings are regularly used by experimental particle physicists and other theoretical particle physicists in their analyses and for their calculations.
Sectors Education

URL http://www.physics.gla.ac.uk/ppt
 
Description Deisa Extreme Computing Initiative
Amount £100,000 (GBP)
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 09/2010 
End 05/2011
 
Description High Performance Computing Grant
Amount £500,000 (GBP)
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 11/2009 
End 10/2012
 
Description HPQCD collaboration 
Organisation University of Cambridge
Department Department of Applied Mathematics and Theoretical Physics (DAMTP)
Country United Kingdom 
Sector Academic/University 
PI Contribution We did the numerical simulations
Collaborator Contribution We have done numerical simulations of QCD using information provided from the mathematical calculations done in Cambridge
Impact several publications and grants for computer time in the USA.
 
Description general article 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Primary Audience Public/other audiences
Results and Impact wrote article for 2Physics.com following their invitation to do so.

several comments posted by those who read it
Year(s) Of Engagement Activity 2010
 
Description school visit 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Primary Audience Schools
Results and Impact around 30 pupils attended, lively discussion

encouraged several applications by potential undergraduates to the physics department
Year(s) Of Engagement Activity 2009,2010
 
Description schoolteachers conference 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Primary Audience Schools
Results and Impact discuss my research with a view to providing teachers with ideas for extra topics/illustration of existing topics within their A-level courses

well-received - impact not yet clear
Year(s) Of Engagement Activity 2011