According to Charles Seife's article in the
June 10th, 2005 issue of
Science, KEK has discovered two bizarre particles:
The numbers indicate masses in MeV. The lighter one (which is a sharper resonance) is most likely a bound state of D0 and D0*, analogous to the nuclei that are bound states of protons and neutrons. The heavier one is more puzzling, and a leading conjecture is that it is an example of a long-sought hybrid meson, i.e. a bound state of quarks connected by an excited (QCD) string - excuse me - an excited gluon fluxtube. Its mass is less sharply well-defined and it often decays to J/psi which a bound state of mesons would not do. More mundane explanations have not been ruled out yet.
