Measurements of the Gluon fusion Fraction in ttbar Production using Azimuthal Correlation of Charged Leptons
in dilepton channel at 2.0 fb-1 data

Naoki Kimura, Yuji Takeuchi, Shinhong Kim
Unibersity of Tsukuba
CDF Collaboration

We present a measurement of the relative fraction of ttbar production through gluon fusion Fgg
using an azimuthal correlation of charged leptons in the ttbar dilepton Channel.
We use a total integrated luminosity of 2 fb-1 data, and find the fraction of gluon fusion
   

Fgg = 0.53	+0.36	(	+0.35	(stat)	+0.07	(syst)	)
	-0.38		-0.37		-0.08

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•  Public Note
•  CDF Internal Page (password protected)

Analysis Detail :

• Motivation

According to standard model, ttbar production is 85% of qqbar annihilation and 15% of gluon fusion. To validate this PQCD calculation
and serch for new physics, we measured this gluon fusion flaction.

• Analysis Methodology
  

qqbar annihilation and gluon fusion have different spin configuration, and this difference can be measure as dangler correlation between
leptons in Azimuthal plane. Finally we fited the data(2fb-1) by this different gluon fusion and qqbar annihilation's Delta Phi leptons distribution.

• Events Selection

We used exact same events selection and background as pre-tag ttbar dilepton channel cross section measurement.

• Template distribution (Delta Phi leptons)
  

Signal gluon fusion	Signal qqbar annihilation	background

•  Uncertaintys
  

• Results
  

   

Fgg = 0.53	+0.36	(	+0.35	(stat)	+0.07	(syst)	)
	-0.38		-0.37		-0.08

Delta Phi Leptons (CDF II preliminary (2fb-1)) and Best fit results	Feldman Cousins Band