Single top quark production with CMS

Measurements of single-top-quark production are presented, performed using CMS data collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV. The cross sections for the electroweak production of single top-quarks in the $t$-channel and in association with W-bosons are measured and the results are used to place constraints on the CKM matrix element $\mathrm{V}_{\mathrm{tb}}$. In the $t$-channel the ratio of top-quark and top-anti-quark production cross sections is determined and compared with predictions from different parton density distribution functions. Measurements of top-quark properties in single-top-quark production are also presented. The results include the W-helicity in top-quark decay, top-quark polarisation and the searches for $s$-channel production.