Measurement of the production cross section for Z + b jets in proton-proton collisions at √s=13 TeV

The measurement of the cross section for the production of a Z boson, decaying to dielectrons or dimuons, in association with at least one bottom quark jet is performed with proton-proton collision data at ffiffiffi s p ¼ 13 TeV. The data sample corresponds to an integrated luminosity of 137 fb−1, collected by the CMS experiment at the LHC during 2016–2018. The integrated cross sections for Zþ ≥ 1 b jet and Zþ ≥ 2 b jets are reported for the electron, muon, and combined channels. The fiducial cross sections in the combined channel are 6.52  0.04ðstatÞ  0.40ðsystÞ  0.14ðtheoÞ pb for Zþ ≥ 1 b jet and 0.65  0.03ðstatÞ  0.07ðsystÞ  0.02ðtheoÞ pb for Zþ ≥ 2 b jets. The differential cross section distribu- tions are measured as functions of various kinematic observables that are useful for precision tests of perturbative quantum chromodynamics predictions. The ratios of integrated and differential cross sections for Zþ ≥ 2b jets and Zþ ≥ 1 b jet processes are also determined. The value of the integrated cross section ratio measured in the combined channel is 0.100  0.005ðstatÞ  0.007ðsystÞ  0.003ðtheoÞ. All mea- surements are compared with predictions from various event generators