If the gluon field tensor is represented as Gμν, then the gluon condensate is the vacuum expectation value . It is not clear yet whether this condensate is related to any of the known phase changes[which?] in quark matter. There have been scattered studies of other types of gluon condensates, involving a different number of gluon fields.
For more on the context in which this quantity occurs, see the article on the QCD vacuum.