Quark-number susceptibility in quenched quantum chromodynamics

Using staggered fermions, we measure the quark-number susceptibility of quenched quantum chromodynamics in a Monte Carlo simulation on an $8^3$×4 lattice. At low temperatures it is consistent with zero and it rises suddenly to nonzero values across the known deconfinement phase transition. Implications for the interpretation of this susceptibility as an indicator of the presence of light baryonic modes in the plasma are discussed.