Observation of Long-Range Collective Flow in O + O and Ne + Ne Collisions and Implications for Nuclear Structure Studies

The long-range collective flow of particles produced in oxygen-oxygen (O+O) and neon-neon (Ne+Ne) collisions is measured with the CMS detector at the CERN LHC. The data samples were collected at a center-of-mass energy per nucleon pair of 5.36 TeV, with integrated luminosities of 7 nb^{-1} and 0.8 nb^{-1} for O+O and Ne+Ne collisions, respectively. Two- and four-particle azimuthal correlations are measured over nearly five units of pseudorapidity. Significant elliptic (v_{2}) and triangular (v_{3}) flow harmonics are observed in both systems. The ratios of v_{n} coefficients between Ne+Ne and O+O collisions suggest sensitivity to the intrinsic nuclear structure of the respective Ne and O ions. Hydrodynamic models with ab initio nuclear structure inputs qualitatively reproduce the collision-overlap dependence of both the v_{n} values and the Ne+Ne to O+O ratios. These measurements provide new constraints when modeling the interplay of nuclear structure and collective dynamics in collisions of ^{16}O and ^{20}Ne ions, respectively.