We are making strides toward comprehending when the powerful nuclear force weakens its influence on the most basic components of matter, causing quarks and gluons within particles to suddenly morph into a hot soup of particles.

There exist unique combinations of temperature and pressure where all three phases of water (liquid, ice, and vapor) coexist simultaneously. For years, scientists have sought similar “critical points” in matter impacted by the potent nuclear force that binds quarks and gluons into protons and neutrons.

In a particle collider, when ions collide, the strong force is disrupted, resulting in a state where quarks and gluons form a soup-like “quark-gluon plasma.” However, it remains uncertain if there is a tipping point preceding this transition. Shinto Researchers at the Lawrence Berkeley National Laboratory in California are getting closer to unraveling this mystery.

They assessed the number and distribution of particles produced after the collision of two high-energy gold ions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory in New York. Dong mentioned they were essentially attempting to formulate a phase diagram for quarks and gluons, depicting what types of matter are generated by strong forces under varied conditions. Although the new experiment did not definitively locate the critical point on this diagram, it significantly narrowed the possible area for its existence.

The phase diagram indicates a region where the material gradually “melts” into plasma, akin to butter softening on a countertop, but a critical point would correspond to a more sudden transition, similar to a chunk of ice unexpectedly forming in liquid water. Agnieszka Sorensen from the Rare Isotope Beam Facility in Michigan, which was not part of the study, stated that this new experiment not only guides researchers in pinpointing this critical point but also uncovers which particle properties might best indicate its presence.

Claudia Ratti from the University of Houston in Texas emphasized that many researchers eagerly anticipated the new analysis due to its precision, which surpasses that of previous measurements, particularly in parts of phase diagrams difficult to theoretically compute. She noted that several predictions regarding the critical point’s location have recently converged, and the challenge for experimenters will now be to analyze data at even lower collision energies that align with these predictions.

Dong remarked that the clear detection of the tipping point would mark a generational milestone. This is significant as the only fundamental force suspected of possessing a critical point is the strong force, which has played a crucial role in the universe’s formation. It governs the characteristics of the hot, dense matter created shortly after the Big Bang and continues to influence the structure of neutron stars. Dong concluded that collider experiments like this one could deepen our understanding of these exotic celestial objects once the strong force phase diagram is finalized.