EMMI Workshop: Light-ion collisions 2026

The observation of collective behavior in small collision systems has raised the fundamental question of how small a system can be while still exhibiting fluid-like dynamics. Recent OO collision measurements suggest that the produced medium may already exhibit fluid-like behavior, motivating investigations of even lighter nuclear systems. In this contribution, we investigate the dynamics of...

We study the bulk collective behaviour in ion collision systems, going from PbPb to light ions, in the context of the Relativistic Boltzmann Transport model. This kinetic theory approach numerically solves the Boltzmann Equation with the full collision integral, including realistic event-by-event initial conditions, a non-conformal equation of state and $\eta/s(T)$. The model is suitable to...

Many features of heavy-ion collisions are well described by hybrid approaches, where the droplet of strongly coupled quark gluon plasma (QGP) is modeled by hydrodynamics and the subsequent dilute stage is performed with a hadronic transport model. Conventionally, the formation of a QGP is well established in larger collision systems like lead and gold. However, hints of collectivity were found...

Highly-energetic heavy-ion collisions are known to produce a viscous relativistic fluid with a very short lifetime that we call Quark-Gluon Plasma (QGP). For such a system to form we need an extraordinarily rapid thermalization that has been explained within the kinetic theory framework for longitudinally boost-invariant expanding systems. These studies assume that the system has an infinite...

Recent experiments with ultracold fermionic gases have demonstrated that even in extremely small systems with only 10 atoms, fluid-like behaviour can emerge [1]. As this is far outside the traditional regime of applicability for hydrodynamics, this ongoing project seeks to understand how this can arise from the microscopic interactions. We briefly review density functional theory (DFT) and...

In an effort to scan the degree of collective behaviour as a function of system size, last year, O+O and Ne+Ne collisions were ran at the LHC, and to great success. Hydrodynamic models were able to accurately predict anisotropic flow, especially ratios of flow harmonics between these two systems, which carry imprints of the tetrahedral shape of oxygen and the bowling pin shape of neon. In this...

Different studies of the initial stage of heavy- and light-ion collision propose that non-trivial azimuthal anisotropies may be produced at very early times. In heavy-ion collisions their effect is expected to be washed out at hydrodynamization time, $\tau_{\mathrm{hydro}}$. However, in scenarios in which the lifetime of the system is comparable to $\tau_{\mathrm{hydro}}$, the observed final...