Kaon fluctuations from lattice QCD

Understand

We show that it is possible to isolate a set of kaon fluctuations in lattice QCD.

• By means of the Hadron Resonance Gas (HRG) model, we calculate the actual kaon second-to-first fluctuation ratio, which receives contribution from primordial kaons and resonance decays, and show that it is very close to the one obtained for primordial kaons in the Boltzmann approximation.
• The latter only involves the strangeness and electric charge chemical potentials, which are functions of $T$ and $\mu_B$ due to the experimental constraint on strangeness and electric charge, and can therefore be calculated on the lattice.
• This provides an unambiguous method to extract the kaon freeze-out temperature, by comparing the lattice results to the experimental values for the corresponding fluctuations.