Measurement of the production cross sections of a Z boson in association with b jets in pp collisions at a center of mass of 7 TeV

The production of a Z boson, decaying into two leptons, and produced in associationwith one or more b jets, have been studied using proton-proton collisions delivered bythe LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector, witha data sample collected in 2011 corresponding to an integrated luminosity of 5 /fb.Cross sections of the Z(ll)+b-jet(s) processes (where ll = ee or mm) are measured forZ bosons produced in association with exactly one or at least two b jets, as well asthe cross section ratio of a Z boson produced in association with any number of b jetsrelative to those containing any number of jets. The cross sections are estimated at theparticle level for events containing leptons with pT gt 20 GeV and IetaI lt 2.4, a dileptoninvariant mass 76 lt M(ll) lt 106 GeV, jets with pT gt 25 GeV and IetaI lt 2.1, anda separation between the leptons and the jets of DR(l, j) gt 0.5. The estimated crosssections are then compared with different theoretical predictions. Also, kinematicproperties are compared with the predictions from the MadGraph event generator,interfaced with Pythia for the parton shower.