Speaker
Description
We present predictions from a perturbative quantum chromodynamics energy loss model that includes small system size corrections and event-by-event hydrodynamic evolution of the medium. The effective strong coupling is constrained by a rigorous statistical analysis of high-$p_T$ suppression data from central heavy-ion collisions at RHIC and LHC.
Extrapolating downwards in system size, we find quantitative agreement with recent $\mathrm{Ne}+\mathrm{Ne}$ and $\mathrm{O}+\mathrm{O}$ $R_{AA}$ measurements, and measurable suppression persisting in very light ions down to ${}^{3}\mathrm{He}+{}^{3}\mathrm{He}$, where deep inelastic scattering data tightly constrain the nPDF baseline.
Strikingly, the same model predicts $v_2 \approx 0$ at high-$p_T$ for all small systems. We argue this prediction is generic to energy loss models when $v_2$ is extracted via the standard experimental method of hard-soft correlations, due to a geometric decorrelation between the hard and soft sector participant planes.
