LHC breaks the record for heaviest antimatter nucleus ever seen

> In 2024, researchers from the STAR Collaboration at Brookhaven National Laboratory’s Relativistic Heavy Ion Collider (RHIC) in New York reported briefly creating a then unprecedentedly heavy antimatter nucleus called **antihyperhydrogen-4.**

> Now, Benjamin Dönigus at Goethe University Frankfurt in Germany and his colleagues from the Large Hadron Collider (LHC) at the CERN particle physics laboratory near Geneva, Switzerland, have upped the ante by creating an even heavier antimatter nucleus: **antihyperhelium-4.**

> Antihyperhelium-4 comprises a mix of antimatter versions of protons, neutrons and particles called **hyperons** that are in themselves exotic because they contain one or more quarks of the strange type. This “strangeness” is hard to find and hard to make. Consequently, researchers still do not fully understand how hyperons behave in nature, where they are thought to occur in exotic settings such as the **interiors of neutron stars,** says Dönigus. Additionally, questions remain about how antimatter versions of these, and other, particles interact with each other.

> “Only two antimatter hypernuclei have been discovered and both in the last 15 years,” says Zhangbu Xu at Kent State University in Ohio. “ The ALICE detector [now] provides the evidence of the third.”