Abstract (data abstract)

- CERN-LHC. The production of single top quarks and top antiquarks via the $t$-channel exchange of a virtual $W$ boson are measured in proton--proton collisions at a centre-of-mass energy of 13 TeV at the LHC. The full Run 2 dataset recorded with the ATLAS detector in the years 2015--2018 is used. The total cross-sections are determined to be $\sigma(tq)=137^{+8}_{-8}\,\mathrm{pb}$ and $\sigma(\bar{t}q)=84^{+6}_{-5}\,\mathrm{pb}$ for top-quark and top-antiquark production, respectively. The combined cross-section is found to be $\sigma(tq+\bar{t}q)=221^{+13}_{-13}\,\mathrm{pb}$ and the cross-section ratio is $R_{t}=\sigma(tq)/\sigma(\bar{t}q)=1.636^{+0.036}_{-0.034}$. The measured cross-sections are in good agreement with predictions made at next-to-next-to-leading order in quantum chromodynamics. The predicted value of $R_{t}$ using different sets of parton distribution functions is compared to the measured value, demonstrating the potential to further constrain the functions when using this result in global fits. The measurements of $\sigma(tq)$, $\sigma(\bar{t}q)$, and $\sigma(tq+\bar{t}q)$ are interpreted in an effective field theory approach, setting limits at the 95\% confidence level on the strength of a four-quark operator and an operator coupling the third quark generation to the Higgs boson doublet: $-0.37 < C_{qQ}^{(1,3)}/\Lambda^2 < 0.06$ and $-0.87 < C_{\phi Q}^{(3)}/\Lambda^2 < 1.42$. The measured total cross-section is further used to derive the constraint $|V_{tb}|>0.95$ at the 95% confidence level. In a more general approach, pairs of CKM matrix elements involving top quarks are simultaneously constrained, leading to confidence contours in the corresponding two-dimensional parameter spaces.

Table 2

Table 2 on page 13 of the paper.

10.17182/hepdata.150693.v1/t1

The 17 variables used for the training of the NN ordered by their discriminating power. The jet that is not...
Table 3

Table 3 on page 21 of the paper.

10.17182/hepdata.150693.v1/t2

The impact of different groups of systematic uncertainties on the $\sigma(tq)$ , $\sigma(\bar t q)$, $\sigma(tq + \bar t q)$...
Table 4

Table 4 on page 22 of the paper.

10.17182/hepdata.150693.v1/t3

The impact of the eight most important systematic uncertainties on the $\sigma(tq)$ , $\sigma(\bar t q)$ and \(\sigma(tq + \bar...
Table 5

Table 5 on page 23 of the paper.

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The impact of the eight most important systematic uncertainties on $R_t$, in %.
Table 6

Table 6 on page 23 of the paper.

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The post-fit yields in the two SRs. All uncertainties applied in the analysis are included.
EFT limits and Vtb

Page 26 of the paper.

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Limits on EFT parameters and Vtb extracted from the analysis. The upper and lower limits correspond to 95% CL.
Results

Page 20 of the paper.

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Results of the main analysis.
SR plus prefit

Figure 6(a) on page 17

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Pre-fit distribution of the NN discriminant $D_{\text{nn}}$ in SR plus.
SR plus postfit

Figure 7(a) on page 22

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Post-fit distribution of the NN discriminant $D_{\text{nn}}$ in SR plus.
muon CR plus postfit

Figure 12(a) on page 31

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Post-fit distribution of the $\Delta\phi(\vec{p}_{T}^{miss},\mu)$ variable in the muon-plus CR.
SR minus prefit

Figure 6(b) on page 17

10.17182/hepdata.150693.v1/t11

Pre-fit distribution of the NN discriminant $D_{\text{nn}}$ in SR minus.
SR minus postfit

Figure 7(b) on page 22

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Post-fit distribution of the NN discriminant $D_{\text{nn}}$ in SR minus.
muon CR minus postfit

Figure 12(b) on page 31

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Post-fit distribution of the $\Delta\phi(\vec{p}_{T}^{miss},\mu)$ variable in the muon-minus CR.
$m(jb)$ prefit

Figure 4(a) on page 15

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Pre-fit distribution of the invariant mass of the untagged jet and the b-tagged jet, $m(jb)$, in SR plus.
$|\eta(j)|$ prefit

Figure 4(b) on page 15

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Pre-fit distribution of the absolute value of the pseudorapidity of the untagged jet, $|\eta(j)|$, in SR plus.
$|\Delta p_{\text{T}}(W, jb)|$ prefit

Figure 4(c) on page 15

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Pre-fit distribution of the absolute value of the difference in $p_{\text{T}}$ between the reconstructed W boson and the jet pair,...
$|\Delta\phi(W, jb)|$ prefit

Figure 4(d) on page 15

10.17182/hepdata.150693.v1/t17

Pre-fit distribution of the difference in azimuth angle between the reconstructed W boson and the jet pair, $|\Delta\phi(W, jb)|$, in...
$m(t)$ prefit

Figure 5(a) on page 16

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Pre-fit distribution of the invariant mass of the reconstructed top quark, $m(t)$, in SR plus.
$|\Delta\eta(\ell ,j)|$ prefit

Figure 5(b) on page 16

10.17182/hepdata.150693.v1/t19

Pre-fit distribution of the absolute value of the difference in pseudorapidity between the charged lepton and the untagged jet, \(|\Delta\eta(\ell...
$\Delta R(\ell ,j)$ prefit

Figure 5(c) on page 16

10.17182/hepdata.150693.v1/t20

Pre-fit distribution of the angular distance of the charged lepton and the untagged jet, $\Delta R(\ell ,j)$, in SR plus.
$|\Delta\eta(b,\ell )|$ prefit

Figure 5(d) on page 16

10.17182/hepdata.150693.v1/t21

Pre-fit distribution of the absolute value of the difference in pseudorapidity between the b-tagged jet and the charged lepton, \(|\Delta\eta(b,\ell...

Table 2

Table 3

Table 4

Table 5

Table 6

EFT limits and Vtb

Results

SR plus prefit

SR plus postfit

muon CR plus postfit

SR minus prefit

SR minus postfit

muon CR minus postfit

\(m(jb)\) prefit

\(|\eta(j)|\) prefit

\(|\Delta p_{\text{T}}(W, jb)|\) prefit

\(|\Delta\phi(W, jb)|\) prefit

\(m(t)\) prefit

\(|\Delta\eta(\ell ,j)|\) prefit

\(\Delta R(\ell ,j)\) prefit

\(|\Delta\eta(b,\ell )|\) prefit

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