Calculations show that relativistic heavy quarks moving through the universe’s first fluid experience large momentum changes far more frequently than standard Brownian motion models predict. phys.org reported that Jean Du Plessis and Bruno Scheihing-Hitschfeld calculated the forces operating on a heavy quark flying through a fluid at close to the speed of light, finding a tilted, uneven probability distribution.
Calculating the Strong Nuclear Force in Relativistic Fluids
The researchers started their study by modeling a relativistic heavy quark moving through a gas of weakly interacting quarks and glouns, providing a manageable baseline for calculations of the strong nuclear force. By computing how much the quark’s momentum changes, the team produced a probability distribution curve. While Albert Einstein established in 1905 that standard Brownian motion yields a symmetric, bell-shaped curve for small kicks in ordinary fluids, the MIT and UCSB calculations revealed a distinct tilt for relativistic heavy quarks.
The resulting tails at either end of the curve proved uneven. Large kicks that slow down the quark happen more frequently than equally large kicks that accelerate it beyond expected drag. This asymmetry indicates that primordial quark-gluon plasma behaves much more like a strongly interacting liquid than a dilute gas.
Detecting Quark-Gluon Plasma in Oxygen Collisions
Experimental evidence for this primordial state of matter continues to emerge from particle collider facilities. UA.news reported that the STAR experiment at the Relativistic Heavy Ion Collider found strong evidence of quark-gluon plasma during oxygen-nucleus collisions at an energy of 200 GeV, analyzing data from a 2021 run. An oxygen nucleus contains eight protons and eight neutrons, allowing physicists to study much smaller systems than the heavier gold nuclei typically used at the facility.
Researchers recorded an approximately 20 percent suppression of high-energy particles associated with jet quenching, where narrow streams of high-energy particles lose energy passing through the post-collision matter. While CERN’s Large Hadron Collider previously observed jet quenching in oxygen collisions at energies exceeding 5,000 GeV, the RHIC measurement establishes a lower limit for the conditions required to form quark-gluon plasma in smaller systems.
Signatures Across Large Hadron Collider Experiments
Additional observations from multiple international collaborations reinforce the presence of plasma-like conditions in compact collision systems. Cadena 3 reported that results from the ALICE, ATLAS, CMS, and LHCb collaborations at the Large Hadron Collider show multiple signatures of quark-gluon plasma in small oxygen and neon collisions. These indicators point to plasma-like conditions without establishing that every individual collision forms the state.
ATLAS measured energy differences between paired jets in oxygen-oxygen and neon-neon collisions, detecting stronger effects in more central collisions. CMS reported suppressed charged-particle production relative to proton-proton collisions. Meanwhile, the LHCb collaboration measured the D⁰-meson production ratio in neon-neon versus oxygen-oxygen collisions at 5.36 TeV per nucleon pair, adding charm-particle observations to the broader dataset.
Frequently Asked Questions About Quark-Gluon Plasma
What is quark-gluon plasma?
Quark-gluon plasma is an ultra-hot and ultra-dense state of matter that existed in the first fraction of a second after the Big Bang, before protons and neutrons formed.
How do heavy quarks reveal the structure of the plasma?
By tracking how heavy quarks move and experience momentum shifts through the fluid, researchers can analyze the microscopic forces and determine whether the plasma behaves more like a liquid or a gas.
What did the Relativistic Heavy Ion Collider measure during oxygen collisions?
The STAR experiment recorded an approximately 20 percent suppression of high-energy particles from jet quenching during 2021 oxygen-nucleus collisions at 200 GeV.
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