EN
Baryon number cumulants are invaluable tools to diagnose the primordial stage of heavy ion collisions. In experiments, however, proton number cumulants have been measured as substitutes. In fact, proton number fluctuations are further modified in the hadron phase and different from those of baryon number. We give formulas that express the baryon number cumulants solely in terms of proton number fluctuations, which are experimentally observable.