Measurement of the ratios of the Z/G* + >= n jet production cross sections to the total inclusive Z/G* cross section in ppbar collisions at sqrt(s) = 1.96 TeV

Abstract

We present a study of events with Z bosons and jets produced at the Fermilab Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV. The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding to the integrated luminosity of 0.4 fb-1 collected using the D0 detector. Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross section have been measured for n = 1 to 4 jet events. Our measurements are found to be in good agreement with a next-to-leading order QCD calculation and with a tree-level QCD prediction with parton shower simulation and hadronization.

Figures (2)

• Figure 1: Ratios of the $Z/\gamma^* +\geq n$ jet cross sections to the total inclusive $Z/\gamma^*$ cross section versus jet multiplicity. The uncertainties on the data (dark circles) include the combined statistical and systematic uncertainties added in quadrature. The dashed line represents predictions of LO Matrix Element (ME) calculations using pythia for parton showering (PS) and hadronization, normalized to the measured $Z/\gamma^* +\geq 1$ jet cross-section ratio. The dotted line represents the predictions of pythia normalized to the measured $Z/\gamma^* +\geq 1$ jet cross-section ratio. The two open diamonds represent predictions from mcfm.
• Figure 2: Comparison between data and theory (ME-PS) for the highest $p_T$ jet distribution in the $Z/\gamma^* + \geq 1$ jet sample (dark circles), for the second highest $p_T$ jet distribution in the $Z/\gamma^* + \geq 2$ jet sample (open circles), and for the third highest $p_T$ jet distribution in the $Z/\gamma^* + \geq 3$ jet sample (open triangles). The uncertainties on the data are only statistical. The MC distributions are normalized to the data.