We point out that the third moments of conserved charges, the baryon and
electric charge numbers, and energy, as well as their mixed moments, change
their signs around the QCD phase boundary in the temperature and baryon
chemical potential plane. These signs can be measured in relativistic heavy ion
collisions, and will give clear information on the phase structure of QCD and
the state of the system in the early stage of relativistic heavy ion
collisions. The behaviors of these moments on the temperature axis and at small
quark chemical potential can be analyzed in lattice QCD simulations. We
emphasize that the third moments obtained on the lattice, together with the
experimental results, will provide a deep understanding about the QCD phase
diagram and the location of the state created in heavy ion collisions.Comment: 7 pages, 2 figures, Contribution to the "XXVII International
Symposium on Lattice Field Theory", July 26-31, 2009, Peking University,
Beijing, Chin