Energy dependence of the deformed nuclear structure at small-$x$

Abstract

We quantify the effect of high-energy JIMWLK evolution on the deformed structure or heavy (Uranium) and intermediate (Ruthenium) nuclei. The soft gluon emissions in the high-energy evolution are found to drive the initially deformed nuclei towards a more spherical shape, although the evolution is slow ,especially for the longest distance-scale quadrupole deformation. We confirm a linear relationship between the squared eccentricity $\varepsilon_n^2$ and the deformation parameter $\beta_n^2$ in central collisions across the energy range covered by the RHIC and LHC measurements. The applied JIMWLK evolution is found to leave visible signatures in the eccentricity evolution that can be observed if the same nuclei can be collided at RHIC and at the LHC, or in rapidity-dependent flow measurements. Our results demonstrate the importance of including the Bjorken-$x$ dependent nuclear geometry when comparing simulations of the Quark Gluon Plasma evolution with precise flow measurements at high collision energies.