Establish whether isospin violation fades at high collision energies

Establish whether the isospin-symmetry violation observed in charged-over-neutral kaon production at SIS, SPS, and RHIC energies fades with increasing collision energy and decreasing baryochemical potential.

Background

ALICE measurements in pp, p+Pb, and Pb+Pb collisions at collision energies from 0.9 to 13 TeV yield charged-over-neutral kaon ratios apparently consistent with unity. However, the experimental uncertainties are approximately 10%, preventing a definitive comparison with the excess observed at lower energies.

The paper therefore identifies the energy evolution of the apparent isospin violation as an unresolved issue requiring more precise high-energy measurements.

References

The question whether the IS violation apparent at SIS/SPS/RHIC energies would fade out with increasing \hspace*{-0.05cm}$\sqrt{s_\mathrm{NN}$ (decreasing baryochemical potential) appears as an issue of great interest, to be solved once more precise experimental data are available.

— Unexpectedly large violation of isospin symmetry in nucleus-nucleus collisions at CERN SPS energies  (2610.23498 - Collaboration, 16 Oct 2026) in Section 3, “Data from ALICE”