JPC=1++ heavy hybrid masses from QCD sum-rules

QCD Laplace sum-rules are used to calculate axial vector (JPC=1++) charmonium and bottomonium hybrid masses. Previous sum-rule studies of axial vector heavy quark hybrids did not include the dimension-six gluon condensate, which has been shown to be important in the 1−− and 0−+ channels. An updated analysis of axial vector heavy quark hybrids is performed, including the effects of the dimension-six gluon condensate, yielding mass predictions of 5.13 GeV for hybrid charmonium and 11.32 GeV for hybrid bottomonium. The charmonium hybrid mass prediction disfavours a hybrid interpretation of the X(3872), if it has JPC=1++, in agreement with the findings of other theoretical approaches. It is noted that QCD sum-rule results for the 1−−, 0−+ and 1++ channels are in qualitative agreement with the charmonium hybrid multiplet structure observed in recent lattice calculations.