Pool CMS_2019_I1744604 – CMS_13

Abstract: A measurement is presented of differential cross sections for $t$-channel single top quark and antiquark production in proton-proton collisions at a centre-of-mass energy of 13 TeV by the CMS experiment at the LHC. From a data set corresponding to an integrated luminosity of 35.9 $\textrm{fb}^{-1}$, events containing one muon or electron and two or three jets are analysed. The cross section is measured as a function of the top quark transverse momentum ($p_\textrm{T}$), rapidity, and polarisation angle, the charged lepton $p_\textrm{T}$ and rapidity, and the $p_\textrm{T}$ of the W boson from the top quark decay. In addition, the charge ratio is measured differentially as a function of the top quark, charged lepton, and W boson kinematic observables. The results are found to be in agreement with standard model predictions using various next-to-leading-order event generators and sets of parton distribution functions. Additionally, the spin asymmetry, sensitive to the top quark polarisation, is determined from the differential distribution of the polarisation angle at parton level to be $0.440 \pm 0.070$, in agreement with the standard model prediction. Rivet: This analysis is to be run separately on t-channel single top quark and top antiquark simulation and the resulting outputs have to be merged for caculating the top quark and antiquark cross section sums and ratios. The particle level selection requires: exactly one dressed lepton (electron or muon; including those from intermediate $\tau$ lepton decay) with $p_{T} > 26$ GeV and $|\eta| < 2.4$; exactly two jets with $p_{T} > 40$ GeV and $|\eta| < 4.7$ that are separated from the dressed lepton by $\Delta R>0.4$. A neutrino candidate reconstructed from the summed transverse momenta of all prompt neutrinos using a W boson mass constraint ($m_\textrm{W}=80.4$ GeV). The four momentum of the top quark is found by summing the dressed lepton, neutrino, and the jet momenta, where the latter is chosen such that a top quark mass closest to 172.5 GeV is obtained. The other jet is taken to be the one that recoils against the W boson in production and used for calculating the top quark polarization angle.

Inspire record | Eur.Phys.J. C80 (2020) 370, 2020 | DOI:10.1140/epjc/s10052-020-7858-1 | arXiv:1907.08330

d13-x01-y01