First measurements on $K/\pi$, $p/\pi$ and $K/p$ fluctuations are measured by the ALICE detector at the CERN LHC as a function of centrality in \PbPb collisions at mbox{\snn~=~2.76~TeV}. The observable \nudyn, which is defined in terms of the moments of particle multiplicity distributions, is used to quantify the magnitude of dynamical fluctuations of particle ratios and also provides insight into the correlation between particle pairs. This study is based on a novel experimental technique, called Identity Method, which allows to measure the moments of multiplicity distributions in case of incomplete particle identification. The results for $p/\pi$ changes sign from positive to negative towards more peripheral collisions. Moreover, for the most central collisions a change of sign for $p/\pi$ and $K/p$ is observed compared to the measurements at lower energies.

PB: https://indico.cern.ch/event/475586/