Abstract
The top quark plays a central role in many New Physics scenarios and in understanding the details of Electro-Weak Symmetry Breaking. In the short- and mid-term future, top-quark studies will mainly be driven by the experiments at the Large Hadron Collider. Exploration of top quarks will, however, be an integral part of particle physics studies at any future facility and an e+e− collider will have a very comprehensive top-quark physics program. We discuss the possibilities of testing NP in the top-quark sector within a composite Higgs scenario through deviations from the Standard Model in top pair production for different Centre-of-Mass energy options of a future e+e− machine. In particular, we focus on precision studies of the top-quark sector at a CM energy ranging from 370 GeV up to 3 TeV.
Highlights
Part of the new particle content of CHMs, both fermions and vector bosons, can manifest itself in ttproduction processes in two ways
We expect that such deviations are all detectable within experimental errors, which are generally claimed to be at the level of percent or even smaller for both the cross section and the asymmetry [38,39,40,41]
Concerning the differential behaviour, the cross section deviations are larger in the backward region while for AL they are slightly bigger for small pT
Summary
The top quark is the heaviest known elementary particle. Thanks to its large mass, and the related strength of its coupling to the Higgs boson, this particle plays a central role in many NP models, in understanding the details of EWSB. The result is that a choice of optimal observables of the lepton angular and energy distributions of events from ttproduction in the lνqqbb final states can give sensitivities to the top-quark EW couplings which are comparable to the ones from a polarised ILC-500. With an e+e− collider, one can in general reach an excellent separation of different NP models while the LHC will not be able to do so even at the high-luminosity option This is clear for the NP scheme we will consider in this paper as a prototype of CHMs. in the right plot of figure 1 we include the points corresponding to the deviations obtained within the 4DCHM (as described ). It is clear that the LHC will not be able to disentangle the 4DCHM by the SM for a wide range of its parameter space.
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