Z(->ee/mumu)
+ jets with b-tagging
Measurement of the Inclusive Cross Section Ratio of Z+b/Z+j
Conference note can be found here (
ps ,
pdf ).
Contact persons: Suyong Choi (suyong@fnal.gov), Kazu Hanagaki (kazu@fnal.gov), Qizhong Li (qzli@fnal.gov), Yildirim Mutaf (mutafy@fnal.gov)
Introduction:
Heavy flavor production in association with the Z boson is the main background for Higgs production associated with Z boson. Observing the Z+b events and
measureing the inclusive cross section ratio of Z+b/Z+j is a interest of many
theorists and experimental physicists.
This analysis is done separately in Z->ee channel and in Z->mumu channel,
then combining these
two analyses we obtain the inclusive cross section ratio of Z+b/Z+j.
Data Sample and Event Selection
The analysis is based on the data collected from April 2002 to September 2003.
The integrated luminosity used in the analysis is 184 pb-1 for dielectron
channel and 152 pb-1 for dimuon channel.
Event Selection Criteria:
- At least two isolated electrons with pT>15 GeV and |eta|<2.5
At least one electron is required to have a matched track
or
- Two isolated muons with pT>15 GeV and |eta|<2.0
The two muon are required to have opposite sign
- 70 GeV < M_ee < 110 GeV or 65 GeV < M_mumu < 115 GeV
b-tag:
A taggable jet is a jet associated with at least one track.
A tagged jet satisfies:
- a secondary vertex with decay length significance > 7
- the openning angle between jet and secondary vertex < 0.5
Plots:
|
eta distribution for taggable jets
( .eps version)
|
pT distribution for taggable jets
(.eps version)
|
|
ee and mumu combined b-jet pT
(.eps version)
|
2D Decay Length Significance
(.eps version)
|
|
a Z(->mumu) + b_jet event
(.eps version)
|
Results:
Combining ee and mumu channel, we measured the ratio of Z+b/Z+j to be
0.024+-0.007.
This page is maintained by Qizhong Li and Suyong Choi
Last modified: Sun May 2 17:00:33 CDT 2004