Investigation of Standard Model Physics and Beyond

Experiments at the Large Hadron Collider (LHC) have confirmed the existence of a Higgs boson, a discovery which led to the 2013 Nobel Prize in physics. The Higgs mechanism is therefore the one chosen by Nature for
the generation of mass. Currently, all measurements of the properties of the newly discovered object are consistent with the Standard Model (SM), the current prevalent description of particle physics. The SM has therefore been remarkably successful, yet it leaves unsolved the following well known puzzles: the large difference between the Electro-Weak and Planck scale, the absence of unification of forces and the problem of flavour. Hence, in spite of the Higgs boson discovery, there remains a need for Beyond the SM (BSM) physics.

This PhD project is to support the research which addresses these questions. The main goal is to provide the theoretical ideas and techniques which will help our experimental colleagues to discover BSM signatures, to influence the analyses which will be performed and to contribute to the theoretical interpretation of the experimental data.

There are many aspects to this task and we now briefly review some of these which could be covered by this project.

The experimental discovery signatures of the Higgs Boson, and indeed of additional new particles possibly present in BSM scenarios, depend on the masses of these particles and on the new theories. In Southampton we have expertise and experience in devising strategies for these searches and also in developing theories of new physics.

Of course, in order to be confident that we have observed a signal of new physics we have to be sure that what we are seeing is not simply a subtle effect of the SM. Frequently, as a result of our limited ability to quantify the effects of the strong nuclear force, which intervenes in all LHC processes, this is difficult to do. In Southampton we have outstanding expertise in Quantum Chromo-Dynamics (QCD), the theory of these strong interactions. This includes a major research programme using state-of-the-art supercomputers to calculate these effects for a wide variety of physical processes.

It is however also possible that some (or perhaps all) new particles will be too heavy to be observed directly at the LHC. In that case their presence will have to be deduced indirectly, by observing deviations from SM predictions for "rare" processes. The programme of collider phenomenology exploiting numerical simulations will be central in establishing these deviations and delineating their properties.

We also have a wide interest in the behaviour of strongly interacting systems which could play a role in BSM and in cosmology. For example, we will study Composite Higgs Models and variants of QCD with very different behaviour. Such systems are also deeply connected to theories of gravitation through a "duality" which provides an alternative description of strong coupling in terms of general relativity, string theory and
black-hole physics. Thus, these studies will shed light on physics from phase transitions in QCD to quantum gravity.