Observation of s-channel production of single top quarks at the Tevatron

We report the first observation of single-top-quark production in the s-channel through the combination of the CDF and D0 measurements of the cross section in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb-1 per experiment. The measured cross section is 1.29+0.26-0.24 pb. The probability of observing a statistical fluctuation of the background to a cross section of the observed size or larger is 1.8E-10, corresponding to a significance of 6.3 standard deviations for the presence of an s-channel contribution to the production of single-top quarks.
Tevatron s-channel combination paper (PRL 112, 231803 (2014), arXiv:1402.5126, FERMILAB-PUB-14-031-E).

Publications by CDF and D0 that form the inputs to this combination

Figures from the PRL

Feynman diagram for single top quark production in the s-channel.
Discriminant distribution ranked by expected signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Posterior probability density distribution for the s-channel single top quark observation.
Summary of Tevatron s-channel single top quark measurements.
Expected and observed significance given by the log-likelihood ratio distribution for the Tevatron s-channel combination.

Supplemental material

Background-subtracted discriminant distribution, ranked by signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Signal region of the background-subtracted discriminant distribution, ranked by signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Discriminant distribution including background composition, ranked by signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Signal region of the discriminant distribution including background composition, ranked by signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Discriminant distribution ranked by expected signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Ranked discriminant distribution of the D0 s-channel-optimized discriminant, including background composition, sorted by signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Signal region of the D0 s-channel discriminant distribution including background composition, ranked by signal/background. The s-channel signal and all backgrounds and the background uncertainty are normalized to their expected value.
Summary of all Tevatron single top measurements.