Separating Zee+ 2 Jets from Top Dilepton ee Decays  

        H. J. Frisch


                               
Intro: These are plots/files of variables of events from MadGraph, so are at generator (parton) level. A delta-R cut of 0.4 has been applied to all visible particles at generator level. The lepton thresholds are 1.0 GeV; the jet thresholds 7.0 GeV. All particles are within abs(eta) < 4.0. For the Z sample only the Z pole is included here (uncharacteristically)- no photon pole events are generated. The electron momenta have been smeared (Gaussian) with 13.5%/root(E), jet momenta by 15% of E, and the underlying event met by 5 GeV in each of the x and y components. This is no substitute for a full simulation, but is easy. The files of these values for each process are the intended input to the likelihood- 1 line per event. The present Zjj sample has 9894 events and the top dielectron has 9996 events. It's trivial to make many more. H.
    Separating Zee+ 2 Jets from Zee+ bbbar  

Approx 10,000 events of each:
Crossection for Zee+2 jet sample is 28.289 \pm 0.108 pb
Crossection for Zee+bbbar sample is 0.333 \pm 0.001 pb
Both have delta-R cuts of 0.4 between the 2 jets (and the lepton+jets)

Note: only plot that is really different is the bbbar mass, as expected- this comes from gluon splitting in Zbbbar. (The met-jet mass plots are a little different too, but it's not going to help much). But all the rest is very close to the same, particularly given jet resolutions. Conclusion is that Zbbbar/top separation will be much like that for Z2jet/top, but is easier in that the cross-section is much lower.


The URL for this page is http://hep.uchicago.edu/cdf/frisch/boos/

Oct. 21, 2004 HJF