Journal Article

Model-independent extraction of absolute value of V.sub.tq matrix elements from top-quark measurements at hadron colliders

Hirschbuhl, D, Luck, J, Zaro, M, Menzel, A, Maltoni, F, Wagner, W, Lacker, H, Spettel, F

2012

Overview

Current methods to extract the quark-mixing matrix element [absolute value of [V.sub.tb]] from single-top-production measurements assume that [absoulute value of [V.sub.tb]] ≫ [absolute value of [V.sub.td]], [absolute value of [V.sub.ts]]: top quarks decay into b quarks with 100% branching fraction, s-channel single-top production is always accompanied by a b quark and initial-state contributions from d and s quarks in the t-channel production of single top quarks are neglected. Triggered by a recent measurement of the ratio R = [[absolute value of [V.sub.tb]].sup.2]/ [[[absolute value of [V.sub.td]].sup.2] + [[absolute value of [V.sub.ts]].sup.2] + [[absolute value of [V.sub.tb]].sup.2]] = 0.90 ± 0.04 performed by the D0 collaboration, we consider a [absolute value of [V.sub.tb]] extraction method that takes into account non zero d-and s-quark contributions both in production and decay. We propose a strategy that allows to extract consistently and in a model-independent way the quark-mixing matrix elements [absolute value of [V.sub.td]], [absolute value of [V.sub.ts]], and [absolute value of [V.sub.tb]] from the measurement of R and from single-top measured event yields. As an illustration, we apply our method to the Tevatron data using a CDF analysis of the measured single-top event yield with two jets in the final state, one of which is identified as a b-quark jet. We constrain the [absolute value of [V.sub.tq]] matrix elements within a four-generation scenario by combining the results with those obtained from direct measurements in flavor physics and determine the preferred range for the top-quark decay width within different scenarios.

• Publisher: Springer