Heaviest exotic antimatter nucleus created in ion collider

Amazing stuff!

"... Now scientists have produced the heaviest antimatter nucleus so far, a substance known as antihyperhydrogen-4. It’s made up of an antiproton, two antineutrons, and an antihyperon. While protons and neutrons are well known, hyperons are less so, but they’re essentially a slightly heavier version of a neutron. ...
these antihyperhydrogen-4 nuclei decay in about one-10th of a nanosecond. ...

From their detections, the team was able to compare the lifetime of antihyperhydrogen-4 to that of hyperhydrogen-4, and found they seem to be the same. ..."

From the abstract:

"At the origin of the Universe, an asymmetry between the amount of created matter and antimatter led to the matter-dominated Universe as we know it today. The origins of this asymmetry remain unknown so far. High-energy nuclear collisions create conditions similar to the Universe microseconds after the Big Bang, with comparable amounts of matter and antimatter.  ... Here we report the observation of the antimatter hypernucleus , composed of a  , an antiproton and two antineutrons. The discovery was made through its two-body decay after production in ultrarelativistic heavy-ion collisions by the STAR experiment at the Relativistic Heavy Ion Collider. In total, 15.6 candidate 

 antimatter hypernuclei are obtained with an estimated background count of 6.4. The lifetimes of the antihypernuclei and  are measured and compared with the lifetimes of their corresponding hypernuclei, testing the symmetry between matter and antimatter. Various production yield ratios among (anti)hypernuclei (hypernuclei and/or antihypernuclei) and (anti)nuclei (nuclei and/or antinuclei) are also measured and compared with theoretical model predictions, shedding light on their production mechanisms."

Heaviest-ever clumps of antimatter created in atom smasher

New Heaviest Exotic Antimatter Nucleus (original news release) "Scientists teasing through six billion particle smashups detect roughly 16 "antihyperhydrogen-4" particles"

Observation of the antimatter hypernucleus (no public access)

An artistic representation of antihyperhydrogen-4 — an antimatter hypernucleus made of an antiproton, two antineutrons, and an antilambda particle — created in a collision of two gold nuclei (left).