The study of minimum bias (MB) and underlying events (UE) is carried out by Dr. I. Dawson. Measuring MB and UE characteristics will allow a better understanding of the structure of the proton at at low-x. This in turn will allow a better understanding of jet backgrounds to SM and BSM physics processes.

So far the work has focussed on understanding and tuning the physics models used in Monte Carlo event generators, using data taken from many experiments at several collider energies. This has allowed us to provide ATLAS with MC tunings at LHC energies for the data challenges. Currently being investigated are track reconstruction issues to allow reconstruction down to lower pT's, which will give better MB and UE measurements.