We present measurements of cross-sections for production of a leptonically decaying Z boson in association with a large-radius jet in 13 TeV proton-proton collisions at the LHC, using 36 fb^-1 of data from the ATLAS detector. Integrated and differential cross-sections are measured at particle-level in both a flavor-inclusive and a doubly b-tagged fiducial phase-space. The large-radius jet mass and transverse momentum, its kinematic relationship to the Z boson, and the angular separation of b-tagged small-radius track-jets within the large-radius jet are measured. This measurement constitutes an important test of perturbative quantum chromodynamics in kinematic and flavor configurations relevant to several Higgs boson and beyond-Standard-Model physics analyses. The results highlight issues with modeling of additional hadronic activity in the flavor-inclusive selection, and a distinction between flavor-number schemes in the b-tagged phase-space.

Measurement of cross sections for production of a Z boson in association with a flavor-inclusive or doubly b-tagged large-radius jet in proton-proton collisions at √s = 13 TeV with the ATLAS experiment

Gaudio G.;Introzzi G.;Livan M.;Negri A.;Pezzotti L.;Rebuzzi D. M.;Rimoldi A.;Sottocornola S.;