Z Forward-backward Asymmetry 364 pb-1

Measurement of Z Forward-backward Asymmetry

Authors: Jedong Lee, Gilles De Lentdecker, Kevin McFarland
Last Updated: May 14^th, 2006

Abstract

We present a measurement of the Z boson forward-backward asymmetry of the process ppbar -> &gamma*/Z + X -> e+e- + X, in the region where the dielectron invariant mass is larger than 50 GeV/c^2. The measurement uses 364/pb of CDF Run II data. The method of matrix inversion is used to correct for the distortion in the measurement caused by the detector resolution and photon radiation in the final state.

Event Selection

Variable	Central	Plug
Fiducial	Fid = 1 or 2	1.18 < \|eta\| < 3.0
E_T	> 25 GeV	> 25 GeV
\|Track Z₀\|	<= 60 cm	N/A
P_T	> 15 GeV (E_T < 100 GeV), > 25 GeV (E_T > 100 GeV)	N/A
E_had/E_em	<= 0.055 + 0.00045 * E	<= 0.05 + 0.026 * log(E/100)
Isolation(GeV)	<= 3 + 0.02 E_T	<= 1.6 + 0.02 E_T
E/p	<= 2.5 + 0.015 E_T (E_T < 100 GeV)	N/A
\|delta X\|	< 3 cm	N/A
\|delta Z\|	< 5 cm	N/A
L_shr	< 0.2	N/A
PEM chi2 3x3	N/A	25
Charge	Opposite charge for CC events. For the CP events, plug electron charge is assumed to be the opposite to the central electron.
M_ee	> 50 GeV

Tables and Plots

	Dielectron invariant mass distribution of data and MC. Energy scale correction is applied. 50-120 GeV. .gif
	Dielectron invariant mass distribution of data and MC. Energy scale correction is applied. 120-600 GeV. .gif
	Dielectron invariant mass distribution of data and MC. Energy scale correction is applied. 500-120 GeV, in ratio. .gif
	Dielectron invariant mass distribution of data and MC. Energy scale correction is applied. 120-600 GeV, in ratio. .gif
	Response matrix .gif
	Unfolded A_FB. Agreement with the LO SM calculation is chi2/ndof = 10.9/12. .gif
	Unfolded A_FB. Residual. .gif
	Unfolded A_FB. Zoomed into the Z pole. .gif
	Unfolded A_FB. Zoomed into the Z pole. Residual. .gif
	Background estimation. .gif
	Raw and unfolded A_FB in 12 bins. .gif
	Summary of uncertainties. .gif

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