EMMI Workshop: Light-ion collisions 2026

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 state might be sensible to this initial state anisotropies. In this talk, we explore how the initial anisotropies relax in the pre-equilibrium stage of the collision due to the final state interactions that we model in the Boltzmann Equation in Diffusion Approximation (BEDA). We find that the azimuthal isotropization time, $\tau_{\mathrm{iso}}$ is comparable to $\tau_{\mathrm{hydro}}$. Besides, we perform a phenomenologically oriented study applied to small systems, finding that, starting from a Color Glass Condensate inspired shape for the initial $v_2(p_T)$, the pre-equilibrium evolution will mimic experimental data in proton-proton and proton-lead collisions.