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posted by chromas on Wednesday March 27 2019, @08:21AM   Printer-friendly
from the omnes-baryonia-est-divisa-in-partes-tres dept.

Experimental physicists Tomasz Skwarnicki, professor of physics in the College of Arts and Sciences at Syracuse University, assisted by Liming Zhang, an associate professor at Tsinghua University in Beijing, analyzed data from the Large Hadron Collider and uncovered three new pentaquarks.

(Normal matter particles, or baryons, consist of three quarks. Pentaquarks are subatomic particles consisting of four quarks and one antiquark. The anti-quark and one quark offset each other creating an exotic baryon particle comprised of five quarks.)

What is unique about each of these three pentaquarks is that its mass is slightly lower than the sum of its parts—in this case, the masses of the baryon and meson. "The pentaquark didn't decay by its usual easy, fall-apart process," Skwarnicki says. "Instead, it decayed by slowly and laboriously rearranging its quarks, forming a narrow resonance."

Skwarnicki notes

"Pentaquarks may not play a significant role in the matter we are made of," he says, "but their existence may significantly affect our models of the matter found in other parts of the universe, such as neutron stars."

There is also a theorized stable pentaquark that could conceivably be produced in appropriately energetic situations, so there might even be a few laying about.


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  • (Score: 0) by Anonymous Coward on Wednesday March 27 2019, @10:15AM (2 children)

    by Anonymous Coward on Wednesday March 27 2019, @10:15AM (#820564)

    Maybe weighing less than it's constituent parts is unique within the pentaquarks we know about, but it's hardly unique without qualification: https://en.wikipedia.org/wiki/Mass_defect#Mass_defect [wikipedia.org] .

    Also, can four antiquarks and a quark not form a pentaquark, or is that called an antipentaquark, or can that not happen for some reason?

  • (Score: 4, Interesting) by PiMuNu on Wednesday March 27 2019, @10:52AM (1 child)

    by PiMuNu (3823) on Wednesday March 27 2019, @10:52AM (#820574)

    > can four antiquarks and a quark not form a pentaquark

    Yes they can.

    > or is that called an antipentaquark

    Often physicists don't bother with the "anti" once you are dealing with things that are not regular matter.

    • (Score: 0) by Anonymous Coward on Wednesday March 27 2019, @11:15AM

      by Anonymous Coward on Wednesday March 27 2019, @11:15AM (#820576)

      Thanks.