The transverse momentum (PT) of W and Z bosons produced in proton-antiproton collisions is coupled to the associated production of one or more gluons or quarks. At low transverse momentum, multiple soft gluon emission is expected to dominate the cross section. In this regime, soft gluon resummation techniques must be used to make reliable QCD predictions. At high transverse momentum, standard perturbative QCD is expected to be applicable. Prescriptions have been proposed for matching the predictions at high and low PT in order to provide a prediction for all PT. In the calculation by Arnold and Kaufmann (AK), next-to-leading order QCD is matched with a resummed calculation at low PT. Two parameters, g1 and g2, are introduced to account for non-perturbative effects. The Ladinsky and Yuan (LY) calculation matches leading order QCD with the resummed region, and introduces an additional non-perturbative parameter, g3.

Also see:

Ratio of W and Z pt differential cross sections

In addition to the individual W and Z pt measurements described below, we have recently studied the ratio of differential cross sections for W and Z boson production. Ratios between W and Z observables can be calculated reliably using perturbative QCD. Using the ratio of differential cross sections reduces the experimental and theoretical uncertainties.

See our measurement of this ratio in the following paper:

*Measurement of the ratio of differential cross
sections for W and Z boson production as a function of transverse momentum
*

Phys. Lett. B {517} 299 (2001)

FERMILAB-Pub-01/212-E, hep-ex/0107012.
PS

The following plots show our results on the W and Z boson differential
cross sections dsigma/dpT .

(Click on the plot to get the postscript file).

**W boson PT distributions - Run 1b data**

Results are described in the following paper:

*Differential Cross Section for W Boson Production
as a Function of Transverse Momentum in pbarp Collisions at sqrt(s)=1.8
TeV*

Phys. Lett. B513, 292 (2001)

FERMILAB-Pub-00/268-E, hep-ex/0010026.
PS

**W boson PT distributions - Run 1a data**

Our results from Run 1a are summarized
here.

**Z Boson PT distributions**

Our latest results, using Run 1b data, are described in the following two publications:

*Measurement of the inclusive differential cross
section for Z bosons as a function of transverse momentum produced in p\bar{p}
collisions at sqrt{s}=1.8 TeV*

Phys. Rev. D {61}, 032004 (2000)
PDF
(Copyright by the APS)

FERMILAB PUB-99/197-E, hep-ex/9907009
PS

* Differential production cross section of Z bosons
as a function of transverse momentum at sqrt(s)=1.8 TeV*

Phys. Rev. Lett. {84} 2792 (2000)
PDF
(Copyright by the APS)

FNAL ?, hep-ex/9909020
PS

Comparison of our unsmeared data with theoretical predictions are shown below. We extract a new values of the non-perturbative parameters g_1, g_2, and g_3, which describe the form of the Sudakov form factor for the low-pT region of Z production. The measurement is primarily most sensitive to the g_2 parameter and we obtain

g_2 = 0.59 +- 0.06 GeV^2

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Last modified: Oct 8 2001