CERN Confirms Top Quarks Pair with Antimatter, Exceeding Discovery Threshold

Researchers at CERN’s Large Hadron Collider, analysing data from 2016-2018, have observed evidence of top quarks momentarily pairing with their antimatter counterparts to form a quasi-bound state termed toponium. The CMS experiment measured a cross section of 8.8 picobarns for this observed excess, with an uncertainty of 1.3 picobarns, exceeding the five sigma level of statistical certainty typically required for a discovery in particle physics. This finding, presented at the European Physical Society’s High-Energy Physics conference, suggests a previously unconfirmed interaction involving these heaviest elementary particles and necessitates further analysis informed by quantum chromodynamics.

Observation of Toponium

The CMS and ATLAS experiments at CERN’s Large Hadron Collider have confirmed an unforeseen feature in the behaviour of top quarks, revealing these particles can momentarily pair with their antimatter counterparts. This fleeting union results in a quasi-bound-state known as toponium, a phenomenon reported at the European Physical Society’s High-Energy Physics conference in Marseille. Further analysis, informed by complex theoretical calculations of quantum chromodynamics (QCD), will be necessary to fully elucidate the nature of this interaction.

High-energy proton-proton collisions at the Large Hadron Collider routinely produce top quark-antiquark pairs, a process used as a crucial test of the Standard Model of particle physics and a means of searching for particles beyond its scope. An unusual surplus of top quark-antiquark pairs was observed by CMS researchers while analysing data collected between 2016 and 2018 during a search for new Higgs bosons. This excess appeared at the minimum energy required to produce such a pair, prompting consideration of the hypothesis of a short-lived union of a top quark and a top antiquark.

Typically, top quarks exist as solitary particles, unlike other quarks which form bound states known as hadrons due to their longer lifetimes. However, quantum mechanics allows for the possibility of a top quark-antiquark pair surviving long enough to exchange gluons, the force-carrying particles of the strong force, and bind into the toponium state, provided they are produced almost at rest relative to each other. Based on a simplified toponium production hypothesis, CMS measured the cross section for the observed top quark-antiquark excess to be 8.8 picobarns (pb) with an uncertainty of approximately 1.3 pb.

This result surpasses the five sigma level of statistical certainty, conventionally required for claiming a discovery in particle physics, indicating that the observed excess is highly unlikely to be attributable to random fluctuations; this is relevant to ongoing top quark research. The measurement provides further evidence for the behaviour of top quarks and their interactions, contributing to the refinement of the Standard Model.

Confirmation via Statistical Analysis

CMS researchers measured the cross section for the observed top quark-antiquark excess to be 8.8 picobarns (pb) with an uncertainty of approximately 1.3 pb, based on a simplified toponium production hypothesis. This result surpasses the five sigma level of statistical certainty, a conventional threshold for claiming a discovery in particle physics. Consequently, the observed excess is highly unlikely to be attributable to random fluctuations, supporting the findings related to top quark research.

Theoretical Implications and Context

Measuring the probability, or cross section, of top quark-antiquark pair production serves as both a crucial test of the Standard Model of particle physics and a means of searching for particles beyond its scope. Last year, CMS researchers observed an unusual surplus of top quark-antiquark pairs while analysing data collected between 2016 and 2018 to search for new Higgs bosons. This excess appeared at the minimum energy required to produce such a pair, prompting consideration of the hypothesis of a short-lived union of a top quark and a top antiquark.

Typically, top quarks exist as solitary particles; unlike other quarks, their extremely short lifetime prevents them from forming bound states known as hadrons. However, quantum mechanics allows for the possibility of a top quark-antiquark pair surviving long enough to exchange gluons – the force-carrying particles of the strong force – and bind into the toponium state, provided they are produced almost at rest relative to each other.

Based on a simplified toponium production hypothesis, CMS measured the cross section for the observed top quark-antiquark excess to be 8.8 picobarns (pb) with an uncertainty of approximately 1.3 pb. This result surpasses the five sigma level of statistical certainty conventionally required for claiming a discovery in particle physics, indicating that the observed excess is highly unlikely to be attributable to random fluctuations.