Measurement of $b$-hadron pair production with the ATLAS detector in proton-proton collisions at $\sqrt{s}=8$ TeV

"A measurement of b-hadron pair production is presented,based on a data set corresponding to an integrated luminosity of 11.4 fb^-1 of proton-proton collisions recorded at sqrtS = 8 TeV with the ATLAS detector at the LHC. The fiducial cross section is measured to be 17.7 +/- 0.1(stat.) +/- 2.0(syst.) nb. A number of normalised differential cross sections are also measured, and compared to predictions from the Pythia8, Herwig++, MadGraph5_aMC@NLO+Pythia8 and Sherpa event generators, providing new constraints on heavy flavour production. See DOI: JHEP 11 (2017) 062 for more details. Events are selected in which a b-hadron is reconstruc- ted in a decay channel containing JPsi -> mumu, and a second b-hadron is reconstructed in a decay channel containing a muon. Results are presented in a fiducial volume defined by kin- ematic requirements on three muons based on those used in the analysis."