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Tuesday, July 27, 2021

Physicists uncover ‘strange’ antihyperparticle

A recent discovery at the United States Department of Energy’s Brookhaven National Laboratory in New York has physicists excited.

The experiment group called “STAR,” located at the Relativistic Heavy Ion Collider (RHIC) in the New York laboratory, found a strange new antihyperparticle called the antihypertriton.

“We have discovered a small of piece of the puzzle that will help physicists understand more about matter and antimatter,” said Manuel Calderon de la Barca Sanchez, an associate professor of physics at UC Davis who is part of the STAR experiment.

STAR Collaboration published a report online in the journal Science last month. Data analysis for antihypertriton was conducted by Jinhui Chen of the STAR Collaboration, a postdoctoral researcher at Kent State University.

Physicists at the Brookhaven Laboratory were using the RHIC to create high-speed collisions of gold particles when they discovered the antihypertriton. The energy released from these collisions forms new particles.

A triton is the nucleus of a hydrogen isotope that consists of a proton and two neutrons. In particle physics, neutrons are made up of three quarks, one “up” and two “down.” One of the neutrons in a hypertriton, on the other hand, is replaced with a lambda hyperon particle. Unlike the neutron, Calderon said, the lambda hyperon contains one “up,” one “down” and one “strange” quark.

Therefore, an antihypertriton is composed of antimatter equivalents to the up, down and “strange” quarks.

“The problem with detecting these antihyperparticles is that they are extremely unstable and decay in fractions of a second or even millionths of a second, “said Rosi Reed, a graduate student in physics at UC Davis, who is part of the STAR experiment.

Researchers worked backwards to identify the antihyperparticle by tracing the trajectory of collision particles. This allowed them to analyze new particles formed from the decay of the original particle, said Daniel Cebra, a UC Davis professor of physics who is involved in ensuring data quality for this research project.

Cebra said that so far, researchers have been able to collect evidence of about 70 antihypertritons from approximately 100 million collisions.

“The laws of physics tell us that the matter and antimatter world are roughly the same,” Calderon said. “However, if you look around, you do not see antimatter all the time, you see matter. So, we know there is a fundamental problem.”

The existing imbalance between matter and antimatter is a phenomenon that physicists still cannot account for.

Calderon said understanding antihyperparticles is a small yet critical piece to perhaps one day answering difficult questions about antimatter.

SRI RAMESH can be reached at campus@theaggie.org.


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