Particle Phenomenology, QCD and the Standard Model.

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Keith Hamilton's research concerns the development of high precision Monte Carlo simulations of collider Physics processes. These facilitate discovery and interpretation of new physics at the Large Hadron Collider (LHC). While precision simulations may not be needed to claim a discovery, e.g. if new physics appears as a clear `bump' in a smooth distribution, (as did the Higgs boson), in many scenarios, such as supersymmetry, signals are expected to manifest as subtle distortions in the shapes of distributions. An accurate understanding of the Standard Model background, subject to all experimental cuts, is then unavoidable for claiming a discovery, or setting exclusion limits. Precision simulations are also essential to determine what it is that has been found. The recently discovered 125 GeV mass Higgs boson is the prime example of this. In 2012-2013 Hamilton and collaborators in Milan and Oxford developed the world's most accurate simulation of Higgs boson production. This simulation is used by the ATLAS collaboration, appearing in their publications confronted with measurements which test various Higgs boson properties. Hamilton plans to fully exploit the innovations which led to the latter simulation, applying them to produce precision simulations of other important LHC reactions, in particular the W-pair and diphoton production processes, where anomalies have been reported in recent experimental measurements. In tandem with application of these new techniques he has helped develop, Hamilton also plans to continue to press on with further innovations in the theoretical frameworks they are based on, towards greater accuracy.Thorne's work is complementary and in many senses similar. It involves the details of the initial state in particle collisions. At colliders which use hadrons, e.g. the LHC which uses protons, the beam is effectively made up of the hadronic constituents, quarks and gluons, generically known as partons. Hence, in order to make predictions for any reaction, both for Standard Model and new physics, one needs to know the precise partonic composition of the hadrons in terms of both the energy fraction of the hadron and the energy scale of the scattering process (e.g., the mass of a particle produced). Thorne is the lead member of the MMHT (previously MSTW) group that provides one of the standard sets of parton distribution functions (PDFs) used in both the experimental and theoretical analyses at the LHC and previous colliders, and in high energy neutrino and cosmic ray physics. The technique is constantly being improved in terms of the theoretical basis, and more data are appearing which help constrain the PDFs further. Hence, Thorne's work will be based on improving PDF determination, providing updated PDFs for use at colliders (and elsewhere) and helping to investigate the consequences of any changes in both central values and uncertainties. Thorne is also a core member of the PDF4LHC working group (being a member of the steering committee since the inception, and hosting the website) which provides recommendations for use of PDF sets at the LHC.Both Hamilton and Thorne are involved in precision calculations at the LHC and will provide expertise in interpreting any deviations which could be the first sign of Beyond the Standard Model (BSM) Physics.