Abstract (data abstract)

A study of the associated production of a Z boson and a charm quark jet (Z+c), and a comparison to production with a b quark jet (Z+b), in pp collisions at a centre-of-mass energy of 8 TeV are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7 fb$^{-1}$, collected with the CMS detector at the CERN LHC. The Z boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of c or b flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with $p_T^l > 20$ GeV, $|\eta_l| < 2.1$, $71 < m_{\ell\ell} < 111$ GeV, and heavy flavour jets with $p_T^{\text{jet}} > 25$ GeV and $|\eta_\text{jet}| < 2.5$. The Z+c production cross section is measured to $\sigma(pp \to Z + c + X) \mathcal{B}(Z \to \ell^+\ell^-) = 8.8 \pm 0.5$ (stat) $\pm 0.6$ (syst) pb. The ratio of the Z+c and Z+b production cross sections is measured to be $\sigma(pp \to Z + c + X)/\sigma(pp \to Z + b + X) = 2.0 \pm 0.2$ (stat) $\pm 0.2$ (syst). The Z+c production cross section and the cross section ratio are also measured as a function of the transverse momentum of the Z boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.

Table 1

Data from Table 1

10.17182/hepdata.85868.v1/t1

Signal yields N(Z+c) and N(Z+b), efficiency*acceptance correction factors C(Z+c) and C(Z+b), cross section sigma(Z+c)B and cross section ratios sigma(Z+c)/sigma(Z+b) in...
Table 2

Data from Table 2

10.17182/hepdata.85868.v1/t2

Z+c and Z+b signal yields, differential cross section dsigma(Z+c)/dpTZ times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTZ...
Table 3

Data from Table 3

10.17182/hepdata.85868.v1/t3

Z+c and Z+b signal yields, differential cross section dsigma(Z+c)/dpTZ times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTZ...
Table 4 upper

Data from Table 4 upper

10.17182/hepdata.85868.v1/t4

Differential cross section dsigma(Z+c)/dpTZ times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTZ for three ranges of the...
Table 4 lower

Data from Table 4 lower

10.17182/hepdata.85868.v1/t5

Differential cross section dsigma(Z+c)/dpTjet times branching ratio and differential cross sections ratio dsigma(Z+c)/dpTZ / dsigma(Z+b)/dpTjet for three ranges of the...
Figure 1 a

Figure 1 a

10.17182/hepdata.85868.v1/t6

Transverse momentum distribution of the selected muon-inside-a-jet for events with an identified muon among the jet constituents in the dielectron...
Figure 1 b

Figure 1 b

10.17182/hepdata.85868.v1/t7

Transverse momentum distribution of the selected muon-inside-a-jet for events with an identified muon among the jet constituents in the dimuon...
Figure 2 a

Figure 2 a

10.17182/hepdata.85868.v1/t8

The invariant mass distribution of three-prong secondary vertices for events selected in the D± mode, in the dielectron channel
Figure 2 b

Figure 2 b

10.17182/hepdata.85868.v1/t9

The invariant mass distribution of three-prong secondary vertices for events selected in the D ± mode, in the dimuon channel
Figure 3 a

Figure 3 a

10.17182/hepdata.85868.v1/t10

The invariant mass distribution of the three-track system composed of a two-prong secondary vertex and a primary particle for events...
Figure 3 b

Figure 3 b

10.17182/hepdata.85868.v1/t11

The invariant mass distribution of the three-track system composed of a two-prong secondary vertex and a primary particle for events...
Figure 4 a

Figure 4 a

10.17182/hepdata.85868.v1/t12

Transverse momentum distribution of the c-tagged jet normalized to unity, in simulated W+c and Z+c samples and in W+c data...
Figure 4 b

Figure 4 b

10.17182/hepdata.85868.v1/t13

Number of reconstructed secondary vertices normalized to unity, in simulated W+c and Z+c samples and in W+c data events.
Figure 5 a

Figure 5 a

10.17182/hepdata.85868.v1/t14

Distribution of the corrected secondary-vertex mass normalized to unity, in simulated W + c and Z + c samples, and...
Figure 5 b

Figure 5 b

10.17182/hepdata.85868.v1/t15

Distribution of the JP discriminant for the D± mode normalized to unity, in simulated W + c and Z +...
Figure 5 c

Figure 5 c

10.17182/hepdata.85868.v1/t16

Distribution of the JP discriminant for the D∗(2010) ± mode normalized to unity, in simulated W + c and Z...
Figure 6

Figure 6

10.17182/hepdata.85868.v1/t17

Distribution of the corrected secondary-vertex mass normalized to unity from simulated Z + b and eμ-tt data events
Figure 7 a

Figure 7 a

10.17182/hepdata.85868.v1/t18

Corrected secondary-vertex mass distributions, after background subtraction in the dielectron channel for events selected in the semileptonic mode.
Figure 7 b

Figure 7 b

10.17182/hepdata.85868.v1/t19

Corrected secondary-vertex mass distributions, after background subtraction in the dimuon channel for events selected in the semileptonic mode.
Figure 8 a

Figure 8a

10.17182/hepdata.85868.v1/t20

Background-subtracted distributions of the JP discriminant in the dielectron channel for Z + jets events with a D± → K∓...
Figure 8 b

Figure 8 b

10.17182/hepdata.85868.v1/t21

Background-subtracted distributions of the JP discriminant in the dimuon channel for Z + jets events with a D± → K∓...
Figure 9 a

Figure 9 a

10.17182/hepdata.85868.v1/t22

Background-subtracted distributions of the JP discriminant in the dielectron channel for Z +jets events with a D∗(2010)± → D0 π±...
Figure 9 b

Figure 9 b

10.17182/hepdata.85868.v1/t23

Background-subtracted distributions of the JP discriminant in the dimuon channel for Z +jets events with a D∗(2010)± → D0 π±...
Figure 10

Figure 10

10.17182/hepdata.85868.v1/t24

ontributions to the systematic uncertainty in the measured Z+c cross section and in the (Z+c)/(Z+b) cross section ratio.
Figure 11 a

Figure 11 a

10.17182/hepdata.85868.v1/t25

Differential Z + c cross section as a function of the transverse momentum of the Z boson
Figure 11 b

Figure 11 b

10.17182/hepdata.85868.v1/t26

(Z +c)/(Z +b) cross section ratio as a function of the transverse momentum of teh Z boson
Figure 11 c

Figure 11 c

10.17182/hepdata.85868.v1/t27

Differential Z + c cross section as a function of the transverse momentum of the jet
Figure 11 d

Figure 11 d

10.17182/hepdata.85868.v1/t28

(Z +c)/(Z +b) cross section ratio as a function of the transverse momentum of the jet.

Table 1

Table 2

Table 3

Table 4 upper

Table 4 lower

Figure 1 a

Figure 1 b

Figure 2 a

Figure 2 b

Figure 3 a

Figure 3 b

Figure 4 a

Figure 4 b

Figure 5 a

Figure 5 b

Figure 5 c

Figure 6

Figure 7 a

Figure 7 b

Figure 8 a

Figure 8 b

Figure 9 a

Figure 9 b

Figure 10

Figure 11 a

Figure 11 b

Figure 11 c

Figure 11 d

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