Event-by-event Particle Yield Ratio Fluctuations in the CBM and NA49 Experiments

Non-statistical event-by-event fluctuations are considered an important signal for the critical endpoint of the QCD phase diagram. Event-by-event fluctuations of different observables are thus investigated in detail in current experiments. In this contribution, a study of the centrality dependence of event-by-event fluctuations of particle yield ratios by the NA49 experiment in Pb+Pb collisions at 158A GeV beam energy is presented for the first time. An increase of the absolute values of dynamical fluctuations towards lower centralities is observed. The influence of resonance decays will be discussed. Event-by-event fluctuations are an important observable to be studied at the future CBM experiment at FAIR. CBM will investigate the intermediate region of the QCD phase diagram in great detail searching for the first order phase transition line and the expected critical endpoint. It is therefore important to investigate the sensitivity of the CBM detector to particle ratio fluctuations in Au+Au collisions at 10-45 AGeV beam energy. Detailed simulation studies will be presented.Comment: proceedings of the CPOD 2009, Brookhaven, US