「小さなビッグバン」を再現――ボウリングピン形の原子核が宇宙初期の姿に新たな光を当てる（Researchers create a Little Big Bang: Bowling-pin-shaped nuclei shed new light on the Universe’s first moments）

2026-08-20 コペンハーゲン大学（UCPH）

The ALICE detector at CERN (credit: Julien Ordan/CERN)

＜関連情報＞

• https://news.ku.dk/all_news/2026/08/researchers-create-a-little-big-bang-bowling-pin-shaped-nuclei-shed-new-light-on-the-universes-first-moments/
• https://journals.aps.org/prl/abstract/10.1103/gymp-vp87

核幾何学駆動異方性流れの証拠O+OそしてNe+Ne衝突事故√SNN=5.36  TeV Evidence of Nuclear Geometry-Driven Anisotropic Flow in O+O and Ne+Ne Collisions at √SNN=5.36  TeV

I. J. Abualrob, S. Acharya, G. Aglieri Rinella, L. Aglietta, N. Agrawal, Z. Ahammed, S. Ahmad, I. Ahuja, Z. Akbar et al. (ALICE Collaboration)
Physical Review Letters  Published: 17 August, 2026
DOI: https://doi.org/10.1103/gymp-vp87

Abstract

A central question in strong-interaction physics, governed by quantum chromodynamics (QCD), is whether femtoscale droplets of quark-gluon plasma form in small collision systems involving projectiles significantly smaller than heavy ions. Collisions of light ions such as ¹⁶O and ²⁰Ne offer a unique opportunity to probe the emergence of collective behavior in QCD matter. This Letter presents the first measurements of the elliptic (ν₂) and triangular (ν₃) flow of charged particles in ¹⁶O–¹⁶O and ²⁰Ne–²⁰Ne collisions at a center-of-mass energy per nucleon pair of √S_NN=5.36  TeV with the ALICE detector. The hydrodynamic model predictions, explicitly incorporating the nuclear structures of ¹⁶O and ²⁰Ne, exhibit a good agreement with the flow measurements presented. The observed increase of ν₂ in central Ne–Ne collisions relative to OO collisions, driven by the nuclear geometries, highlights the importance of utilizing light nuclei with well-defined geometric shapes to constrain the initial conditions. These findings support the presence of nuclear geometry-driven hydrodynamic flow in light-ion collisions at the LHC.