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.
-rich entities might be tight combinations of particles with fewer quarks
rather than a single, quark
-laden particle, Swanson says.
-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.