Abstract
Measurements are presented of differential cross sections for the production of Z bosons in association with at least one jet initiated by a charm quark in pp collisions at sqrt{s} = 13 TeV. The data recorded by the CMS experiment at the LHC correspond to an integrated luminosity of 35.9 fb−1. The final states contain a pair of electrons or muons that are the decay products of a Z boson, and a jet consistent with being initiated by a charm quark produced in the hard interaction. Differential cross sections as a function of the transverse momentum pT of the Z boson and pT of the charm jet are compared with predictions from Monte Carlo event generators. The inclusive production cross section 405.4 ± 5.6 (stat) ± 24.3 (exp) ± 3.7 (theo) pb, is measured in a fiducial region requiring both leptons to have pseudorapidity |η| < 2.4 and pT> 10 GeV, at least one lepton with pT> 26 GeV, and a mass of the pair in the range 71–111 GeV, while the charm jet is required to have pT> 30 GeV and |η| < 2.4. These are the first measurements of these cross sections in proton-proton collisions at 13 TeV.
Highlights
Z at b√osso=ns1i3nTaeVss.oTcihateiodnatwa irtehcoartdleedasbtyotnhee jet initiated by a CMS experiment charm at the quark in pp collisions LHC correspond to an integrated luminosity of 35.9 fb−1
The final states contain a pair of electrons or muons that are the decay products of a Z boson, and a jet consistent with being initiated by a charm quark produced in the hard interaction
Differential cross sections as a function of the transverse momentum pT of the Z boson and pT of the charm jet are compared with predictions from Monte Carlo event generators
Summary
The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. A silicon pixel and strip tracker, covering a pseudorapidity region |η| < 2.5, a lead tungstate crystal electromagnetic calorimeter (ECAL), and a brass and scintillator hadron calorimeter, with each system composed of a barrel and two endcap sections, lie within the solenoid volume. Made of steel and quartz fibers, extend η coverage provided by the barrel and endcap detectors to |η| < 5. Events of interest are selected using a two-tiered trigger system [7]. The first level, composed of specialized hardware processors, uses information from the calorimeters and muon detectors to select events at a rate of ≈100 kHz within a fixed latency of about 4 μs. The second level, known as the high-level trigger, consists of a farm of processors running full event reconstruction software optimized for fast processing, that reduces the event rate to ≈1 kHz before data storage. A more detailed description of the CMS detector, together with a definition of the coordinate system and kinematic variables, can be found in ref. [8]
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