RevModPhys.84.1477】Tests of the standard electroweak model at the energy frontier

K is an overall normalization parameter for process k

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: jth process such P that j kj ¼ 1. The templates of the LRWW distribution are created for signal and each background process given in Table X. A binned maximum likelihood is used to extract the WW production cross section from the shape and normalization of the LRWW templates. The likelihood is formed from the Poisson probabilities of observing ni events in the ith bin when i are expected. Variations corresponding to the systematic uncertainties described previously are included as normalization parameters for signal and background, constrained by Gaussian terms. The likelihood is given by Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 ∆ λ Z = 0.16 - 10 2 Events / 20 GeV c-1 LRWW (10) c SM W W PWW P ¼ ; PWW þ kj Pj 1 FIG. 18 (color online). The LRWW distributions for the signal (W þ W À ) and background processes after a maximum likelihood fit to the data for the CDF WW cross-section measurement. From Aaltonen et al., 2010a. k (7) - Background Data 10 ∆ gZ = 0.34 ∆κ γ = 0.72 1 1 10 -1 10 -2 0 50 100 150 200 250 300 350 400 450 500 Lepton p [GeV c-1] T FIG. 19 (color online). Leading-lepton pT distribution for data compared to the SM expectation for the CDF WW ! ‘‘ analysis (Aaltonen et al., 2010a). Also shown is how the expectation would be modified by anomalous couplings near the observed limits. Hobbs, Neubauer, and Willenbrock: Tests of the standard electroweak model at . . . Data 20 WW Z/γ *→ll 10 -1 (b) ee+eµ+ µµ DØ, 1 fb 40 Events / 15 GeV/c Events / 12.5 GeV/c -1 (a) ee+eµ+ µµ DØ, 1 fb 30 Multijet, W/Z+j/γ WZ,ZZ 30 20 tt 0 50 100 150 Leading Lepton p (GeV/c) Ã (TeV) 0 50 100 150 Trailing Lepton p (GeV/c) T T FIG. 20 (color online). Distributions of the (a) leading and (b) trailing lepton pT for the D0 WW ! ‘‘ analysis (Abazov et al., 2009e). Data are compared to the estimated signal ðWW Þ ¼ 12 pb and the background sum. The fit to the data of the signal and sum of the individually fitted background templates is shown in Fig. 18. The measured WW production cross section is " ðpp ! WW þ X Þ ¼ 12:1 Æ 0:9ðstatÞ1:6 :4 ðsystÞ pb À1 (Aaltonen et al., 2010a) in agreement with the NLO theoretical expectation of 11:7 0:7 pb (Campbell and Ellis, 1999). Both of the CDF and D0 WW cross-section measurements are consistent with the SM expectations at NLO. CDF searches for anomalous WW and WWZ couplings using the observed leading charged-lepton pT spectrum (see Fig. 19). In the D0 analysis, the subleading (trailing) lepton pT is also included in a 2D histogram with the leading lepton -1 DØ, 1 fb 0.4 (a) -1 DØ, 1 fb 0.4 (b) 0.2 λγ 1 ∆ gZ 0.2 0 -0.2 -0.4 -1 0.4 (c) 0 ∆κ γ 1 -1 -1 DØ, 1 fb 0.2 (d) 0 ∆κ γ 1 -1 DØ, 1 fb 1 0 -0.2 1.5 1.5 2.0 2.0 (À 0:05, (À 0:16, (À 0:05, (À 0:14, 0.07) 0.16) 0.06) 0.15) Á (À 0:23, (À 0:63, (À 0:20, (À 0:57, 0.31) 0.72) 0.27) 0.65) ÁgZ 1 (À 0:09, (À 0:24, (À 0:08, (À 0:22, 0.17) 0.34) 0.15) 0.30) pT to constrain possible anomal...
View Full Document

This document was uploaded on 09/28/2013.

Ask a homework question - tutors are online