Physicists detect hints of exotic matter in particle collisions
Scientists at CERN have observed an unexpected excess of events when smashing top quarks together, suggesting a rare form of matter may exist. The finding could reshape understanding of fundamental particles and may eventually unlock new materials or energy applications, though further validation is needed.
Originaltitel: Observation of a pseudoscalar excess at the top quark pair production threshold
<p>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 √s = 13TeV, corresponding to 138 fb<sup>−1</sup>. 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 withthe production of a color-singlet pseudoscalar (<sup>1</sup>S<sup>[1]</sup><sub>0</sub>) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for <sup>1</sup>S<sup>[1]</sup><sub>0</sub> toponium, thecross section of the excess above the pQCD prediction is measured to be 8.8<sup>+1.2</sup><sub>−1.4 </sub>pb.</p>