Abstract
Associated production of bottomonia and open charm hadrons in $pp$ collisions at $\sqrt{s}=7$ and $8$TeV is observed using data corresponding to an integrated luminosity of 3$fb^{-1}$ accumulated with the LHCb detector. The observation of five combinations, $\Upsilon(1S)D^0$, $\Upsilon(2S)D^0$, $\Upsilon(1S)D^+$, $\Upsilon(2S)D^+$ and $\Upsilon(1S)D^+_{s}$, is reported. Production cross-sections are measured for $\Upsilon(1S)D^0$ and $\Upsilon(1S)D^+$ pairs in the forward region. The measured cross-sections and the differential distributions indicate the dominance of double parton scattering as the main production mechanism. This allows a precise measurement of the effective cross-section for double parton scattering.
Highlights
Detector and data sampleThe LHCb detector [46, 47] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks
The requirements favour the selection of charm hadrons produced promptly at the pp collision vertex and significantly suppress the feed down from charm hadrons produced in decays of beauty hadrons
The associated production of Υ mesons with open charm hadrons is observed in pp collisions at centre-of-mass energies of 7 and 8 TeV using data samples corresponding to integrated luminosities of 1 fb−1 and 2 fb−1 respectively, collected with the LHCb detector
Summary
The LHCb detector [46, 47] is a single-arm forward spectrometer covering the pseudorapidity range 2 < η < 5, designed for the study of particles containing b or c quarks. The tracking system provides a measurement of the momentum, p, of charged particles with a relative uncertainty that varies from 0.5% at low momentum to 1.0% at 200 GeV/c. The online event selection is performed by a trigger [48], which consists of a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, which applies a full event reconstruction. Events for this analysis are selected ger than requiring dimuon 1.7 (2.6) GeV2/c2 candidates with a product √. In the subsequent software trigger, two well reconstructed tracks are required to have hits in the muon system, to have pT > 500 MeV/c and p > 6 GeV/c and to form a common vertex. The interaction of the generated particles with the detector, and its response, are implemented using the Geant toolkit [53, 54] as described in ref. [55]
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