Search for Single-top Production at Cdf

This article reports on recent searches for single-top-quark production by the CDF collaboration at the Tevatron using a data set that corresponds to an integrated luminosity of 955 pb. Three different analyses techniques are employed, one using likelihood discriminants, one neural networks and one matrix elements. The sensitivity to single-top production at the rate predicted by the standard model ranges from 2.1 to 2.6 σ. While the first two analyses observe a deficit of single-top like events compared to the expectation, the matrix element method observes an excess corresponding to a background fluctuation of 2.3 σ. The null results of the likelihood and neural network analyses translate in upper limits on the cross section of 2.6 pb for the t-channel production mode and 3.7 pb for the s-channel mode at the 95% C.L. The matrix element result corresponds to a measurement of 2.7 −1.3 pb for the combined tand s-channel single-top cross section. In addition, CDF has searched for non-standard model production of single-top-quarks via the s-channel exchange of a heavy W ′ boson. No signal of this process is found resulting in lower mass limits of 760GeV/c in case the mass of the right-handed neutrino is smaller than the mass of the right-handed W ′ or 790GeV/c in the opposite case.