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
|
Documents :
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.
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.
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
|
![](jpg_pub/Fit_GSIG_DelPhiLep_all_2mjet_SignalR_v2.jpg)
|
![](jpg_pub/Fit_QSIG_DelPhiLep_all_2mjet_SignalR_v2.jpg) |
![](jpg_pub/Fit_bkg_DelPhiLep_all_2mjet_SignalR_v2.jpg)
|
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
|
![](jpg_pub/Data_Fit_final.jpg)
|
![](jpg_pub/FC_results_final.jpg)
|
Last
modified by Naoki Kimura at July 07, 2008