Electric charge fluctuations from lattice QCD in the continuum limit

Abstract

Electric charge fluctuations ${\chi }_n^Q$ allow comparisons between theory and experiment, but are elusive on the lattice due to severe cutoff effects. We use a 4HEX action to obtain ${\chi }_2^Q$ and, for the first time ever, ${\chi }_4^Q$ in the continuum limit. We find disagreement with the hadron resonance gas (HRG) model, which we cannot explain with finite volume effects. We include light meson interactions in the HRG model via the S-matrix, reducing the tension for ${\chi }_4^Q$, but worsening the agreement for ${\chi }_2^Q$. We propose measuring the ratio ${\chi }_4^Q/{\chi }_2^Q$ at the LHC to investigate this tension.

Comments: 10 pages, 5 figures