I work on the ATLAS experiment at the CERN Large Hadron Collider (LHC). I led a UCL group which contributed to the tracking, trigger and software. My own work has focussed on physics processes at the LHC which will help us discover more about electroweak symmetry breaking, or basically "why some things have mass". This included searching for the Higgs boson, discovered in July 2012. I wrote some of the first papers on using the substructure of hadronic jets to identify the decays of boosted, massive particles - including the Higgs. I am now working on using precision measurements at the LHC to constrain or characterise physics beyond the Standard Model. I was convener of the ATLAS Monte Carlo group (2007-2009) and of the ATLAS Standard Model group (2010-2012).

Until 2008 I worked on ZEUS experiment at the HERA electron proton collider at DESY in Hamburg. I made the first measurements of the photoproduction of hadronic jets. I was physics chair of the experiment in 2003-2004. I led efforts to translate HERA data to have an impact at the LHC.

I have made several contributions to theory/phenomenology, including writing the widely used "JIMMY" programme to simulate multiparton interactions, other apects of QCD at colliders, supesymmetty, WW scattering, and jet substructure.