New Antimatter Hypernucleus Discovered by Chinese Academy of Sciences

TapTechNews August 22nd news, in the research of participating in the RHIC-STAR international cooperative experiment, the Institute of Modern Physics, Chinese Academy of Sciences, for the first time observed a new antimatter hypernucleus - anti-hyperhydrogen-4 in relativistic heavy ion gold-gold collisions, which is also the heaviest antimatter hypernucleus found experimentally so far.

Project Background

What are positive matter and antimatter? Current physics knowledge believes that at the beginning of the birth of the universe, there should be positive matter and antimatter, and both exist in equal amounts.

But now it is difficult to find antimatter in the universe, so many people are curious, where did all the antimatter go? The answer given by scientists is that antimatter is very easy to annihilate with the surrounding positive matter, that is, it disappears as soon as it exists.

If the positive and antimatter in the universe keep the same number all the time, they will eventually be completely annihilated and turn into a ball of light. Fortunately, under the action of a certain physical mechanism, there is an imbalance in the number of positive and antimatter.

However, a certain mysterious physical mechanism leads to a very small asymmetry in the number of positive and antimatter in the early universe. After most of the positive and antimatter are annihilated, about one billionth of the positive matter survives and constitutes today's material world and becomes the basis for the birth and existence of human civilization.

Antimatter is very rare, and antimatter atomic nuclei and antimatter hypernuclei (that is, atomic nuclei containing hyperons such as Lambda) formed by further combination of several anti-baryons are even more difficult to produce.

Since the negative energy solution of the Dirac equation in 1928 predicted the existence of antimatter, for nearly a century, scientists have only discovered 6 kinds of antimatter (hyper)nuclei.

Research Process

Qiu Hao introduced that the newly discovered anti-hyperhydrogen-4 was produced in the relativistic heavy ion collision experiment. The Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory in the United States can accelerate heavy ion beams to nearly the speed of light and make them collide to simulate the state of the early universe in the big bang in the laboratory.

This kind of collision can produce a high-temperature fireball of tens of thousands of degrees Celsius, including almost equal amounts of positive matter and antimatter. The fireball expands and cools rapidly, so that some antimatter has a chance to escape the fate of annihilation with positive matter and be observed by the STAR experiment detector surrounding the collision point.

Introduction to Anti-Hyperhydrogen-4

Anti-hyperhydrogen-4 is composed of one anti-proton, two anti-neutrons and one anti-Lambda hyperon. Due to the inclusion of the unstable anti-Lambda hyperon, anti-hyperhydrogen-4 decays after flying only a few centimeters.

The research team analyzed the experimental data of about 6.6 billion heavy ion collision events in total, and reversely reconstructed anti-hyperhydrogen-4 through the anti-helium-4 and π+ mesons produced by decay, and finally obtained about 16 signals of anti-hyperhydrogen-4.

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