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Résumé |
The CMS and ATLAS experiments have observed spin correlation effects
and a cross section excess near threshold in top-antitop production at
the LHC. They have attempted to explain these observation by assuming
that they arise from the contribution of a top-antitop bound state to the
production cross section. I will discuss the dynamics of top-antitop
production and of their spin correlations near threshold, that is
dominated by non-relativistic Quantum Chromodynamics Coulombic
interaction. This discussion is realtively elementary, since it is
carried out in the context of
non-relativistic quantum mechanics. I will show that when
all non-relativistic effects are included, the description of the
phenomenon cannot simply be represented by the production of a bound
state, and that, on the other hand, the dominant effects are
calculable in perturbation theory. Finally I will assess the current
status of the comparison of the experimental measurements with the
theoretical calculation. |
