Evidence for Production of Single Top Quarks and First Direct Measurement of |V_tb|

Authors

V. M. Abazov, Joint Institute for Nuclear Research, Dubna, Russia
Kenneth A. Bloom, University of Nebraska-LincolnFollow
Gregory R. Snow, University of Nebraska-LincolnFollow
D0 Collaboration

Document Type

Article

Date of this Version

5-4-2007

Comments

Published in PHYSICAL REVIEW LETTERS 98, 181802 (2007). © 2007 The American Physical Society. Used by permission.

Abstract

The D0 Collaboration presents first evidence for the production of single top quarks at the Fermilab Tevatron pp̅ collider. Using a 0.9 fb^-1 dataset, we apply a multivariate analysis to separate signal from background and measure σ (pp̅ → tb + X, tqb + X) = 4.9 ± 1.4 pb. The probability to measure a cross section at this value or higher in the absence of a signal is 0.035%, corresponding to a 3.4 standard deviation significance. We use the cross section measurement to directly determine the Cabibbo- Kobayashi-Maskawa matrix element that describes the Wtb coupling and find 0.68 < |V _tb| ≤ 1 at 95% C.L. within the standard model.