A method to determine |Vcb| at the weak scale in top decays at the LHC

Abstract Until now, the Cabibbo Kobayashi Maskawa matrix element, |Vcb|, has always been measured in B decays, i.e. at an energy scale %$ {q}_b\sim \frac{m_b}{2} %$, far below the weak scale. We consider here the possibility of measuring it close to the weak scale, at qW ∼ mW, in top decays at the L...
Ausführliche Beschreibung

Abstract Until now, the Cabibbo Kobayashi Maskawa matrix element, |Vcb|, has always been measured in B decays, i.e. at an energy scale %$ {q}_b\sim \frac{m_b}{2} %$, far below the weak scale. We consider here the possibility of measuring it close to the weak scale, at qW ∼ mW, in top decays at the Large Hadron Collider (LHC). Our proposed method would use data from the LHC experiments in hadronic top decays %$ t\to b{W}^{+}\to b\overline{b}c %$, tagged by the semileptonic decay of the associated top. We estimate the uncertainty of such a measurement, as a function of present and potential future experimental jet flavour-tagging performances, and conclude that first measurements using the data collected during 2016-2018 could yield a fractional error on |Vcb| of order 7% per experiment. We also give projected performances at higher luminosities, representative of those anticipated at LHC Run 3 and HL-LHC. Ausführliche Beschreibung