Patrick Janot edited Outlook.tex  about 9 years ago

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\section{Summary and outlook}  In this paper, it has been shown that the measurements of the angular and energy distributions in semi-leptonic ${\rm t\bar t}$ events (${\rm e^+e^- \to t \bar t} \to \ell \nu {\rm q \bar q b \bar b}$ b}$)  at future ${\rm e^+e^-}$ colliders have a strong potential for a precise determination of the top-quark electroweak couplings. It has been demonstrated, even with the sole use of these two distributions and modest detector performance, that  the lack of incoming beam polarization at the FCC-ee ismore than  compensated by the use polarization  of the final state polarization top quarks,  and by a significantly larger integrated luminosity, even with the sole use of the lepton energy and angular distributions, and modest detector performance. luminosity.  The present study is only a first look at this topic for Although these projections were obtained with somewhat conservative hypotheses on  the FCC-ee. It enhances detector performance, it will also be important to reproduce  the fantastic potential of a 100-km circular ${\rm e^+e^-}$ collider already envisioned in Ref.~\cite{Bicer_2014} results  with the a  full profiling of the top quark from simulation in  a precise measurement of its electroweak couplings. It becomes now of particular interest Monte Carlo study, as  to check further investigate that  the added value of these measurements to detector requirements are indeed quite modest. While  the sensitivity to new physics, when combined inferred precisions are already competitive  with other projects on  the unequalled precision of the measurements market, such a Monte Carlo study will allow a reliable reconstruction  of all observables in  the Z, event, beyond  the W, lepton energies  and directions, and is expected to bring sizeable improvements, especially on  the Higgs boson properties, as well as of the top-quark mass, at the FCC-ee. few remaining correlations between form factors.  Although the The  present projections were obtained with somewhat conservative hypotheses on the detector performance, it will also be important to reproduce these results with study is only  a Monte Carlo study, as to further investigate that first look at this topic for  the detector requirements are indeed quite modest. While FCC-ee. It enhances  the inferred precisions are fantastic potential of a 100-km circular ${\rm e^+e^-}$ collider  already competitive envisioned in Ref.~\cite{Bicer_2014}  withother projects on  the market, this study will benefit from, for example, the energy and angular distrbutions full profiling  of the b-quark jets and top quark from a precise measurement of its electroweak couplings. In view of these new estimates, it becomes of particular interest to check  their correlations with added value to  the lepton distributions, sensitivity  to improve new physics, especially when combined with  the unequalled  precision on all couplings and in particular on $F_{1A}^Z$. Finally, the CP-violating form factors, ignored in this study for of  the sake measurements  ofan easy comparison with Ref.~\cite{Baer_2013}, will have to be included too. Event variables, such as  the asymmetry between Z,  the negative W,  and the positive lepton distributions~\cite{Grzadkowski_2000}, will be interesting to study in this perspective. Higgs boson properties, as well as of the top-quark mass, at the FCC-ee.