AtlasMeeting_29_10_08

Table of Sherpa numbers for fully leptonic ttbar cross-section:

Problems I can think of so far with the analysis.

*charge veto implimented in AOD too soon.

*muon isolation implimented in AOD too soon before electron definition.

-- KennyWraight - 29 Oct 2008

For WZ the W decays inclusively and the simluation is filtered for at least 2 leptons.For ZZ the Z's decay inclusively and the sample is filtered for at least 2 leptons. The reason for this is that WZ and ZZ produce dileptons through inefficiencies in the detector where 1 or 2 leptons are lost. For WZ one lepton may come from W and one from Z with a lepton from Z lost.

Wgamma produces a lepton plus a conversion lepton and the third lepton in the conversion is lost. This has a rapidity dependence since material increases with increasing |eta|. Same sign leptons are a good monitor of this background.

The Drell Yan has a section below mll< 20 added to the mll>20 to get reasonable statistics for the spectrum down to mll of order 10-12 GeV. This is relevant for Higgs but perhaps not top.

Cross sections taken at NLO are just given and those at LO with a k factor are indicated.

Section 11 has top analysis, with yields in table 31 on page 74. Here they are reproduced:

It is interesting to compare the 70 ttbar events in 3fb-1 at 1960 GeV to the 140 that Kenny has in his talk with 14000 GeV. It will be interesting to compare the background to those shown above.

The W+jet background is estimated from the data by taking dijet events, identifying one jet and asking how often the other passes loose lepton cuts compared to how often it passes full lepton id. This defines the fake probability. The single lepton sample is then searched and events with jets that are found to pass the loose lepton cuts are given a weight according to the measured probability. The kinematics and numbers of these events are then used in the analysis.

• cdf9402_HWW_30_V2.pdf: CDF 3.0 fb dilepton higgs WW analysis