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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Experimentelle Elementarteilchenphysik

Humboldt-Universität zu Berlin | Mathematisch-Naturwissen­schaft­liche Fakultät | Institut für Physik | Experimentelle Elementarteilchenphysik | ATLAS | Publikationen | Model-independent extraction of |Vtq| matrix elements from top-quark measurements at hadron colliders

Heiko Lacker, Andreas Menzel, Fabian M Spettel, Dominic Hirschbühl, Jan Lück, Fabio Maltoni, Wolfgang Wagner, and Marco Zaro (2012)

Model-independent extraction of |Vtq| matrix elements from top-quark measurements at hadron colliders

Eur. Phys. J. C, 72:1644.

Current methods to extract the quark-mixing matrix element |Vtb| from single-top production measurements assume that |Vtb|≫|Vtd|,|Vts|: 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=|Vtb|^2/(|Vtd|^2+|Vts|^2+|Vtb|^2)=0.90±0.04 performed by the D0 collaboration, we consider a |Vtb| 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 |Vtd|, |Vts|, and |Vtb| 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 |Vtq| 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.