Top Cross Section Using Jet Probability

- Authors: Javier Cuevas, Gervasio Gómez, Enrique Palencia, Teresa Rodrigo, Luca Scodellaro, Alexander Sukhanov, Rocío Vilar and Song Ming Wang. Send us an e-mail

- Introduction:

In this analysis we present a measurement of the production cross section of top-antitop pairs in approximately 318 inverse picobarns of Run II data at CDF. The Jet Probability tagger is applied to events with a lepton + missing transverse energy signature. To purify the data sample and improve the significance of the measurement, a cut on the scalar transverse energy sum is applied. We also use the transverse mass of the leptonic W-boson to further reduce the Non-W background. Backgrounds are computed from Run II data and Monte Carlo simulation. Signal acceptance is determined from Run II signal (top mass=178~GeV/c) Pythia Monte Carlo. Finally, we measure

ttbar cross section	Single Tag	Double Tag
JP < 1%	8.9 + 1.0 - 1.0 ± 1.1	11.1 + 2.3 - 1.9 ± 1.9
JP < 5%	9.6 + 1.0 - 0.9 ± 1.2	11.6 + 1.7- 1.5 ± 1.9

- Documents:

Public note: Measurement of the ttbar Production Cross Section in the Jet Probability Tagged Sample in ppbar Collisions at sqrt{s}=1.96 TeV

- Blessed Plots and Tables:

Efficiency to tag b-jets in a top Monte Carlo sample vs the Et and eta of the jet (Click on any image to get a larger version of the figure and here to get the ps). The bands represent the systematic error on the data/Monte Carlo scale factors

Average efficiency for tight b-jets and c-jets jets after ttbar selection (ps)

b-jets	Monte Carlo	Scaled
JP < 1%	43.2 ± 0.1 %	35.3 ± 3.0 %
JP < 5%	54.6 ± 0.1 %	46.5 ± 3.9 %

c-jets	Monte Carlo	Scaled
JP < 1%	9.6 ± 0.2 %	7.8 ± 0.7 %
JP < 5%	20.3 ± 0.2 %	17.3 ± 1.5 %

Jet Probability Mistag rate for Jet Probability cuts of 0.01 and 0.05 as a function of the Et and eta of the jet (Click on any image to get a larger version of the figure and here to get the ps). They are derived from an inclusive jet data sample which includes all of the 5.3.3 jet20, jet50, jet70 and jet100 datasets. The bands represent the total uncertainty: statistical and systematic added in quadrature. The systematic uncertainty is 6.7% for JetProb<0.01 and 4.7% for JetProb<0.05

Yield of events in 318 inverse picobarns of RunII data (ps)

Selection acceptance and tagging efficiency for top pair production events (ps)

Summary of the background estimate before and after correction for signal contribution to the pretagged sample (ps)

Tagged background contributions and results from data as a function of event jet multiplicity (Click on any image to get a larger version of the figure and here to get the ps)

Single 1% tag analysis with the theoretical (left) and measured (right) cross section

Double 1% tag analysis with the theoretical (left) and measured (right) cross section

Single 5% tag analysis with the theoretical (left) and measured (right) cross section

Double 5% tag analysis with the theoretical (left) and measured (right) cross section

Summary of statistical uncertainties (ps)

Summary of systematic uncertainties (ps)

Probability to measure our double tag cross section given the single tag measurement for different values of the scale factor (ps)

	SF - sigma	SF	SF + sigma
JP < 1%	4.5 %	13.2 %	30 %
JP < 5%	2.8 %	15.6 %	35 %

Kinematic distributions

Single and double tag analyses with JP < 1%
Single and double tag analyses with JP < 5%