Physicists Detect Mysterious X Particles in 'Primordial Soup' For The First Time - ScienceAlert

Specifically, in a medium called the quark-gluon plasma, generated in the Large Hadron Collider by colliding lead ions.

There, amid the trillions of particles produced by these collisions, physicists managed to tease out 100 of the exotic motes known as X particles.

Instead, for a few millionths of a second, it was filled with plasma superheated to trillions of degrees, consisting of elementary particles called quarks and gluons.

In less time than it takes to blink, the plasma cooled and the particles came together to form the protons and neutrons of which normal matter is constructed today.

Theoretically, however, X particles could appear in the very small flashes of quark-gluon plasma that physicists have been creating in particle accelerators for some years now.

"Theoretically speaking, there are so many quarks and gluons in the plasma that the production of X particles should be enhanced," Lee says.

Physicists believe that X particles may be made of four – either an exotic, tightly bound particle known as a tetraquark, or a new kind of loosely bound particle made from two mesons, each of which contain two quarks.