, 2011:136,
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Date: 28 Mar 2011

Measurement of \( {\text{B}}\overline {\text{B}} \) angular correlations based on secondary vertex reconstruction at \( \sqrt {s} = 7\,{\text{TeV}} \)


A measurement of the angular correlations between beauty and anti-beauty hadrons (\( {\text{B}}\overline {\text{B}} \)) produced in pp collisions at a centre-of-mass energy of 7 TeV at the CERN LHC is presented, probing for the first time the region of small angular separation. The B hadrons are identified by the presence of displaced secondary vertices from their decays. The B hadron angular separation is reconstructed from the decay vertices and the primary-interaction vertex. The differential \( {\text{B}}\overline {\text{B}} \) production cross section, measured from a data sample collected by CMS and corresponding to an integrated luminosity of 3.1 pb−1, shows that a sizable fraction of the \( {\text{B}}\overline {\text{B}} \) pairs are produced with small opening angles. These studies provide a test of QCD and further insight into the dynamics of \( {\text{b}}\overline {\text{b}} \) production.