Measurement of the hadronic activity in events with a Z and two jets and extraction of the cross section for the electroweak production of a Z with two jets in pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper reports the first measurement of the electroweak production cross section of a Z boson with two jets at 7 TeV, using CMS data, and explores hadronic activity relevant for Higgs and gauge boson studies.

Contribution

It provides the first experimental measurement of Z boson production with two jets via electroweak processes at the LHC, validating theoretical predictions.

Findings

Measured cross section: 154 +/- 24 (stat) +/- 46 (exp syst) +/- 27 (th syst) +/- 3 (lum) fb.

Hadronic activity in the rapidity interval between jets was characterized.

Results agree with theoretical expectations.

Abstract

The first measurement of the electroweak production cross section of a Z boson with two jets (Zjj) in pp collisions at sqrt(s) = 7 TeV is presented, based on a data sample recorded by the CMS experiment at the LHC with an integrated luminosity of 5 inverse femtobarns. The cross section is measured for the lljj (l = e, mu) final state in the kinematic region m[ll] >50 GeV, m[jj] > 120 GeV, transverse momenta pt[j] > 25 GeV and pseudorapidity abs(eta[j]) < 4.0. The measurement, combining the muon and electron channels, yields sigma = 154 +/- 24 (stat.) +/- 46 (exp. syst.) +/- 27 (th. syst.) +/- 3 (lum.) fb, in agreement with the theoretical cross section. The hadronic activity, in the rapidity interval between the jets, is also measured. These results establish an important foundation for the more general study of vector boson fusion processes, of relevance for Higgs boson searches and for measurements of electroweak gauge couplings and vector boson scattering.