The Status of Glueballs

Understand

Calculations within QCD (lattice and sum rules) find the lightest glueball to be a scalar and with mass in the range of about 1000-1700 MeV.

• Several phenomenological investigations are discussed which aim at the identification of the scalar meson nonets of lowest mass and the super-numerous states if any.
• Results on the flavour structure of the light scalars f0(500), f0(980) and f0(1500) are presented; the evidence for f0(1370) is scrutinized.
• A significant surplus of leading clusters of neutral charge in gluon jets is found at LEP in comparison with MCs, possibly a direct signal for glueball production; further studies with more energetic jets at LHC are suggested.