A search for resonances in top quark pair (tt-) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC at sqrt(s)=13TeV, corresponding to 138 fb-1. The analysis explores the invariant mass of the tt- system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematic tt- threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar (1S0[1]) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for 1S0[1] toponium, the cross section of the excess above the pQCD prediction is measured to be 8.8-1.4+1.2 pb.

Observation of a pseudoscalar excess at the top quark pair production threshold

Fabozzi, F.;
2025-01-01

Abstract

A search for resonances in top quark pair (tt-) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC at sqrt(s)=13TeV, corresponding to 138 fb-1. The analysis explores the invariant mass of the tt- system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematic tt- threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar (1S0[1]) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for 1S0[1] toponium, the cross section of the excess above the pQCD prediction is measured to be 8.8-1.4+1.2 pb.
2025
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11563/208716
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