Hello. My name is Oveis Sheibani. I am a postdoctoral physics researcher.
I work on Quantum Chromodynamics, the theory of how quarks and gluons bind into the protons and neutrons that ordinary matter is made of. Most of what we touch and see, the chemistry of materials, the colors of light, the workings of biology, sits a layer above this. My work sits underneath it.
The strong force does not behave the way the other forces do. It does not weaken with distance. It grows stronger, which is why a single quark has never been seen on its own. Quarks are kept inside the particles they help to form. To study them at all, we collide heavy nuclei at speeds close to the speed of light, and for an instant the protons and neutrons come undone. The quarks and gluons inside flow together as a fluid.
That fluid is the Quark-Gluon Plasma. It is most clearly produced in lead-lead collisions at the LHC, where it forms a small, hot droplet about ten femtometers across, and lives for less than a millionth of a billionth of a second. It is the smallest thermodynamic system anyone has measured, and the hottest matter ever made in a laboratory. In its brief life it resembles the state of the universe at a few microseconds of age.
Some of the signatures of this plasma, collective flow and strangeness enhancement among them, have started to appear in much smaller collisions, in particular in high-multiplicity proton-proton events. Whether what we are seeing in pp is the same plasma in a smaller form, or something different that only mimics it, is not yet settled. It is one of the questions I spend most of my time on.