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The particles' masses, decay products and other data indicated a composition of a charm quark, its antimatter counterpart, two up quarks and a down quark.
A baryon is a mixture of three quarks such as that a proton is composed of two up quarks and one down quark and that a neutron is composed of one up quark and two down quarks.
Its mass, says Poling, who is part of the BESIII team, suggests that it is an electrically neutral meson made up of two quarks with opposite charges, called charm and anticharm.
When the team examined their data, the researchers realized that the sought-after quark combinations had shown up.
That's partly because the rules of quantum mechanics permit countless additional quarks and other particles to continually flit in and out of existence inside each hadron.
They've found a system of quarks and gluons that's very different from normal nuclear matter," says Joseph Kapusta of the University of Minnesota, Twin Cities.
Experiments and current theories suggest that quarks existed in isolation only in the first 0.
Particles called baryons, such as protons and neutrons, contain three quarks or antiquarks each.
Such quark-rich entities might be tight combinations of particles with fewer quarks rather than a single, quark-laden particle, Swanson says.
Because charm-quark-containing particles are so readily produced at HERA, researchers belonging to what's known as DESY's H1 team decided to seek evidence of pentaquarks containing charm quarks in data from past HERA runs.
From previous experiments, scientists knew that only valence quarks can grab major portions of a nucleons total energy content, says Jian-Ping Chen of the Jefferson lab, a coleader of the experiment.
The discovery of yet other combinations of quarks and antiquarks could illuminate the force that binds quarks and antiquarks together.