Measurement of the Single Top Quark Production Cross Section at CDF

TL;DR

This paper reports a measurement of the single top quark production cross section at Fermilab, confirming the standard model prediction with a significance of 3.7 standard deviations.

Contribution

It combines three analysis methods to improve sensitivity and provides the first measurement of the cross section and CKM matrix element |V_{tb}| from this dataset.

Findings

Measured cross section: 2.2 pb with uncertainties

Significance of signal: 3.7 standard deviations

Limit on |V_{tb}|: greater than 0.66 at 95% CL

Abstract

We report a measurement of the single top quark production cross section in 2.2 ~fb-1 of p-pbar collision data collected by the Collider Detector at Fermilab at sqrt{s}=1.96 TeV. Candidate events are classified as signal-like by three parallel analyses which use likelihood, matrix element, and neural network discriminants. These results are combined in order to improve the sensitivity. We observe a signal consistent with the standard model prediction, but inconsistent with the background-only model by 3.7 standard deviations with a median expected sensitivity of 4.9 standard deviations. We measure a cross section of 2.2 +0.7 -0.6(stat+sys) pb, extract the CKM matrix element value |V_{tb}|=0.88 +0.13 -0.12 (stat+sys) +- 0.07(theory), and set the limit |V_{tb}|>0.66 at the 95% C.L.