Extreme geometrical effects on relativistic isobaric collisions

The chiral magnetic effect (CME) is a phenomenon that could explain the dominance of matter over antimatter in the universe. Initially, symmetric isobaric collisions of Ruthenium (⁹⁶₄₄Ru) and Zirconium (⁹⁶₄₀Zr) nuclei were considered ideal for eliminating possible background signals when considering the ratio, potentially yielding a CME signal. However, in experiments, there are still multiple non-CME signals that make the detection of small CME signals difficult. The spectator protons produce a huge magnetic field, and therefore, understanding the initial magnetic field generated in isobaric collisions is necessary for studying the possible chiral charge separation and its alignment with the participant plane. In this study, we perform a beam energy scan (BES) analysis for several Relativistic Heavy Ion Collider energies (7.7, 9.2, 11.5, 14.6, 17.3, 19.6, 27, 39, and 200 GeV) and Large Hadron Collider energies (2.76, 5.02, and 5.44 TeV) per nucleon using a Glauber Monte Carlo formulation to study their effect on the initial magnetic field produced in isobaric collisions, in order to obtain a better understanding of magnetic field evolution in such systems. We found that for most central to mid-central events, the ratio ⟨B₂cos2(ψ_B​−ψ₂​)⟩_Ru​/⟨B₂cos2(ψ_B​−ψ₂​)⟩_Zr​ increases with energy as expected, but in most peripheral events, the ratio for the highest-energy collisions moves below that of all other energies.