Breaking News:CERN’s ALICE Collaboration Finds Evidence Of Quark-Gluon Plasma In Proton Collisions– What Just Happened

Researchers with the ALICE Collaboration at the Large Hadron Collider have found evidence that a state of matter resembling the earliest moments of the universe, quark-gluon plasma, can arise even in collisions of comparatively small particles like protons. Previously, physicists believed that generating quark-gluon plasma required the extreme energy of heavy ion collisions; however, this new analysis of proton-proton and proton-lead collisions reveals a similar pattern of anisotropic flow, where particles emerge with a directional preference. This flow is stronger in baryons, particles composed of three quarks, than in mesons with only two. “This is the first time we have observed, for a large interval in momentum and for multiple species, this flow pattern in a subset of proton collisions in which an unusually large number of particles are produced,” says David Dobrigkeit Chinellato, Physics Coordinator of the ALICE experiment, suggesting that an expanding system of quarks may form even in smaller collision systems.

Anisotropic Flow Distinguishes Baryons and Mesons in Multiple Collisions

This observation challenges earlier assumptions that quark-gluon plasma formation required the extreme conditions generated only by collisions of larger nuclei like lead. Researchers initially proposed that smaller systems lacked the necessary temperature and pressure, but recent evidence suggests otherwise. A crucial aspect of this research centers on the differing behavior of baryons, composed of three quarks, and mesons, containing only two; the ALICE team meticulously isolated particles exhibiting collective flow to analyze this distinction. The analysis revealed that, mirroring observations in heavy-ion collisions, baryons demonstrated a stronger anisotropic flow than mesons at intermediate momenta, a phenomenon explained by a process called quark coalescence, where quarks within the quark-gluon plasma combine to form larger particles. The team validated these findings by comparing the observed flow to simulations incorporating quark-gluon plasma formation and quark coalescence; models accurately reflecting these processes successfully reproduced the observed patterns, while those omitting them failed. Kai Schweda, ALICE Spokesperson, anticipates further refinement of these models with data from oxygen collisions recorded in 2025, which promises a deeper understanding of quark-gluon plasma evolution across varying collision systems and its implications for the earliest moments of the universe.

ALICE Collaboration Validates Quark Coalescence Models of QGP Evolution

The search for quark-gluon plasma, the state of matter theorized to have existed moments after the Big Bang, has expanded beyond collisions of massive lead nuclei; recent investigations at the Large Hadron Collider suggest quark-gluon plasma may also form in smaller systems. The ALICE Collaboration published findings in Nature Communications detailing a consistent pattern observed across proton-proton, proton-lead, and lead-lead collisions, providing further evidence for quark-gluon plasma creation even in less energetic interactions. Initial assumptions held that the extreme temperatures and pressures necessary for quark-gluon plasma formation were unattainable in smaller collisions, but accumulating data challenges this view.