# Measurement of the single top quark cross section and the CKM matrix element $|V_{tb}|$ at the Tevatron

We present combinations of CDF and D0 measurements of single top quark production cross sections 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 the $t$-channel cross section is measured to be $\sigma_t = 2.25^{+0.29}_{-0.31}$ pb. We also measure the $s$- and $t$-channel cross sections simultaneously and the $s+t$ combined cross section resulting in $\sigma_{s+t} = 3.30^{+0.52}_{-0.40}$ pb. We measure the modulus of the CKM matrix element as $|V_{tb}| = 1.02^{+0.06}_{-0.05}$ and set a lower limit of $|V_{tb}| > 0.92$ at $95\%$ C.L.
Tevatron s+t combination note (CDF note 11113, D0 note 6448)

## Figures from the paper

 Discriminant distribution ranked by (s-channel - t-channel)/background with background composition. The s-channel and t-channel signals and all backgrounds and the background uncertainty are normalized to their expected value. Two-dimensional posterior probability density distribution for the s-channel vs t-channel single top quark signals. The measurement is compared to the SM prediction as well as several different BSM models. Summary of all Tevatron single top measurements. Posterior probability density distribution for the s+t channel single top quark production with the yellow region indicating the allowed values of $|V_{tb}|^{2}$.