Northwest Terascale Research Projects: Modeling the underlying event and minimum bias events

Topics to be discussed

This is a follow-on to the UO workshop "Parton showers and event structure at the LHC", 23 - 27 February 2009, but with a little different focus and with the benefit of early LHC data. The focus is on what the LHC data is telling us about the underlying event in hard scattering events and on the structure of minimum bias events. Having good models for this is important for sharpening our ability to distinguish new physics signals from backgrounds at the LHC. We will discuss how what we are learning in early LHC running differs from what we saw at the Tevatron, how the parton shower event generators are doing with the description, and what QCD theory says about what sorts of theoretical descriptions should be best.

These topics were discussed at a workshop at DESY September. There, recent tunes of Pythia taking LHC data into account were discussed and comparisons of Herwig and Pythia to this data were presented. One could note that Pythia has a more detailed approach while Herwig has what might be called a more minimalist approach to the underlying event. Since the the Pythia and Herwig approaches are different, there ought to be some tests that one can pass and the other cannot. Our workshop could discuss that. Both of the Pythia and Herwig models are based on multiple parton scattering. There was also discussion at DESY of the theory behind multiple parton scattering, which is more subtle than what has been traditionally assumed. Our workshop can discuss that.


Last updated 17 December 2010

Davison E. Soper
Institute of Theoretical Science
University of Oregon
Eugene OR 97403 USA