Revolutionary discovery: Researchers find toponium at the LHC!

Revolutionary discovery: Researchers find toponium at the LHC!

Researchers of the University of Hamburg and DESY have made groundbreaking advances in particle physics by finding evidence of the particle toponium. Toponium arises from a bound state between a top quark and its antiparticle, the anti-top quark. This discovery could provide crucial new insights into the fundamental structure of all matter.

The advance was made possible by signals obtained in two experiments Large Hadron Collider (LHC) of CERN were identified. The top quark, the heaviest known elementary particle, decays in less than a quadrillionth of a second, underscoring what was considered an extremely challenging assumption to observe bound states. Until now, the opinion was that such a state could not be detected with the antiparticle, but new data is shaking this view.

Discovery in experiments

The discovery of toponium was made independently in the CMS and ATLAS experiments at the LHC. According to the researchers, a larger amount of top quarks with low kinetic energy were measured, which enables the formation of toponium. The first indications of toponium were already in the CMS experiment in 2016, which was reinforced with additional data from 2017 and 2018. ATLAS was able to confirm the connection using its own data, which further underlines the relevance of the results.

Laurids Jeppe, a doctoral student at the University of Hamburg, emphasizes that the precision achieved when measuring rare processes is remarkable. The results achieved were carried out at the High Energy Physics Conference of the European Physical Society.

In addition, the analyzes of the CMS experiment reveal an unexpected property in the behavior of top quarks. This observation suggests that top quarks briefly form a “quasi-bound state” with their antiparticles, called toponium. This discovery is not only surprising, but could also foreshadow new particles that test the limits of the current Standard Model of particle physics.

Measurements and their meaning

The CMS experiment found the production cross section for the excess of top quark-antiquark pairs to be 8.8 picobarns (pb), with an uncertainty of 1.3 pb, achieving a “five sigma” level of confidence. The ATLAS collaboration found that the same effects were confirmed in the overall LHC Run-2 data, measuring the production cross section to 9.0±1.3 pb and excluding significant models that ignore the formation of a quasi-bound state.

An alternative explanatory model could involve the existence of a new particle with a mass close to twice the mass of the top quark. However, in order to conclusively interpret the phenomena, precise modeling of the behavior of quarks and gluons in high-energy collisions is required.

The discovery of Toponium would not only expand the understanding of Quarkonia, but also direct the research landscape to new ways of studying the strong interaction. These formations of heavy quark-antiquark pairings already represent the previous discoveries of charmonian and bottomonian in the 1970s, and the ongoing third phase of the LHC is expected to provide additional data to further explore top quark-antiquark interactions.