Measurement of textB[`(textB)] {text{B}}overline {text{B}} angular correlations based on secondary vertex reconstruction at Ös = 7 textTeV sqrt {s} = 7,{text{TeV}}

摘要

A measurement of the angular correlations between beauty and anti-beauty hadrons ( textB[`(textB)] {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 textB[`(textB)] {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 textB[`(textB)] {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 textb[`(textb)] {text{b}}overline {text{b}} production.