Categoria: General Revisiting the theory of spin correlations and entanglement in top pair production at the LHC - Prof. Paolo Nason (Milano Bicocca)

Revisiting the theory of spin correlations and entanglement in top pair production at the LHC - Prof. Paolo Nason (Milano Bicocca)


Maggio 20, 2025

Seminario di Fenomelogia

Recent ATLAS and CMS studies of spin correlations and entanglement in top pair production at hadron colliders have evidenced some inadequacy in the current modeling of the process of top pair production and decay. It has been argued that one needs to include the effect of a very short lived $t{bar t}$ pseudoscalar bound state to reconcile the data with the theoretical prediction. In this talk I review the problem, and argue that in fact standard perturbation theory is enough to correctly describe these phenomena, withot the need to resum threshold enhance corrections to all orders and deal with bound states. A simple quantum mechanical model is used to show that shows that the leading correction due to bound state formation has the same form as other corrections that arise from from the continuum right above threshold, and that the combination of two leads to a well defined expansion in perturnation theory. Furthermore, by examining critically the calculation of the process as implemented in current Monte Carlo generators, I show that these corrections, that are of the third subleading order in the strong coupling constant, are tiny, while threshold enhanced corrections of first and second subleading order (not related to bound states) seem to be enough to understand the current <a href="http://discrepancies.

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Aula 603

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