Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

TL;DR

This paper measures the cross section of Z/gamma* boson production with b jets in proton-proton collisions at 7 TeV using CMS data, and compares the results with theoretical predictions.

Contribution

First measurement of Z/gamma* + b-jet cross section at 7 TeV with detailed kinematic analysis and comparison to MadGraph and PYTHIA simulations.

Findings

Measured cross section: 5.84 pb with uncertainties.

Event kinematics agree with MadGraph + PYTHIA predictions.

Results provide validation for theoretical models of b-jet production.

Abstract

The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.