Studies of 2 b-jet + 2 jet production in proton-proton collisions at 7 TeV

Measurements are presented of inclusive differential two b- and two-jet production cross sections as a function of the transverse momentum $p_\text{T}$, pseudorapidity $\eta$, as well as of correlations in azimuthal angle $\phi$, pseudorapidity $\eta$ and $p_\text{T}$ balance among the jets. The data sample was collected from proton-proton collisions at a centre-of-mass energy of 7~TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 3.03 pb$^{-1}$. The jets are reconstructed with the anti-$k_T$ jet algorithm with $p_\text{T}$ $>$ 20 GeV. At least four jets are required: two jets need to be originated by a bottom quark within the range of pseudorapidity $|\eta|$ $<$ 2.4, while the other two jets are required to be in $|\eta|$ $<$ 4.7 without any flavour requirement on the initial quark. Only the two leading jets of each selection are considered. The cross section is measured to be $\sigma$(pp$\rightarrow$ 2 b + 2 j + X) = 64.6 $\pm$ 2.4 (stat.) $\pm$ 21.6 (syst.) nb. Various model predictions are compared to the measured differential cross sections. The data agree within uncertainties with the predictions of parton shower Monte Carlo event generators and with NLO calculations matched to parton showers only in some regions of the phase space.