Public: Lepton + Jets ttbar cross section with SLTmu b-tagging

Measurement of tt Production Cross Section

with SLTμ b-Tagging

**Alice Bridgeman, Lucio Cerrito+, Ulysses Grundler,**

**Tony Liss*,** Xiaojian Zhang*

*University of Illinois Urbana-Champaign

+University College London

We present a measurement of the tt production cross section in ~2 fb^-1 of CDF Run 2 data. The Soft Muon Tagger (SLT) is applied to events with a lepton + 3-or-more jets and missing E_T. Backgrounds are computed from a combination of Run 2 data and simulation. Signal acceptance is determined from Run 2 Pythia Monte Carlo. Based on the tags in the 3 and 4-jet bins, a production cross section of

is measured.

Public Note

	Summary of background contributions, tt expectation (s_tt=6.7 pb), and observed tags.
	SLT_m tagged events vs. jet multiplicity.
	Summary of systematic uncertainties.

Various kinematic distributions (1,2 jets)	Various kinematic distributions (3-or-more jets)






	Estimated mistags, both raw and corrected by (1-F_QCD)
	Summary of QCD background estimation.
	Summary of Drell-Yan background estimation.

	Mass difference, M(Kpp)-M(Kp), showing sharp peak consistent with D*→D⁰p→Kpp decay. The p_T range is that of the SLT taggable track. Other p_T ranges.
	Mass, M(pp), showing peak consistent with L⁰→pp decay. The p_T range is that of the SLT taggable track. Other p_T ranges.
	Tag rate vs. invariant mass. Inside the D* signal region, the rate is dominated by the p and K tag rate, but outside that region there are also muons that may be tagged, resulting in a higher rate.
	Invariant mass, M(pp), in two different SLT taggable track p_T ranges. The relative peak height over the sideband changes with taggable p_T indicating different fractions of background under the peak.
	Measured and sideband subtracted pion tag rates vs. p_T.
	Measured and sideband subtracted kaon tag rates vs. p_T.
	Measured and sideband subtracted proton tag rates vs. p_T.
	Relative abundances of various particle types in W+jets taggable tracks. Plot is normalized to sum of pion, kaon, and proton contributions. Other types of particles are not common amongst SLT_m taggable tracks.
	Tag rate vs. p_T of finalized mistag matrix.
	Tag rate vs. h offinalized mistag matrix.
	Fraction of taggable jets that contain heavy flavor as a function of the maximum impact parameter significance allowed in an event.
	Fraction of taggable tracks that are from decays-in-flight (DIF) as a function of the maximum impact parameter significance allowed in an event. Plot shows no bias created with cut on d₀ significance at 2. Inset shows the number of taggable tracks from DIF vs. the maximum impact parameter significance allowed in an event.
	Left: Agreement between predicted and observed tags in generic jets as a function of jet E_T. Above: Same results in tabular form.
	Jet E_T spectrum in W+jets (MC). The W+≥3-jets spectrum is used to weight the results above to determine an average agreement. The weighted average D=(pred.-obs.)/pred. is (0.1±4.4)% from which we assign a systematic of 5%.
	Agreement between predicted and observed tags in various jet samples.
	Agreement between predicted and observed tags in various jet samples using double SLT_m tagged jets. The agreement is not bad but, due to limited statistics, is only used as a cross check.