A study of proton-proton collisions in which two b hadrons are produced in association with a Z boson is reported. The collisions were recorded at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC, for an integrated luminosity of 5.2 inverse femtobarns. The b hadrons are identified by means of displaced secondary vertices, without the use of reconstructed jets, permitting the study of b-hadron pair production at small angular separation. Differential cross sections are presented as a function of the angular separation of the b hadrons and the Z boson. In addition, inclusive measurements are presented. For both the inclusive and differential studies, different ranges of Z boson momentum are considered, and each measurement is compared to the predictions from different event generators at leading-order and next-to-leading-order accuracy.
CMS, Basegmez, S., Beluffi, C., Bruno, G., Castello, R., Caudron, A., Ceard, L., Delaere, C., Du Pree, T., Favart, D., Forthomme, L., Giammanco, A., Hollar, J., Jez, P., Lemaitre, V., Liao, J., Militaru, O., Nuttens, C., Pagano, D., et al. (2013). Measurement of the cross section and angular correlations for associated production of a Z boson with b hadrons in pp collisions at sqrt(s) = 7 TeV. Journal of High Energy Physics, 1312, 39. https://doi.org/10.1007/JHEP12(2013)039 (Original work published 2013)