arXiv subjects
Publications and source records attributed to N. F. Nasrallah.
A QCD sum rule calculation of Balistky and Ji on the spin content of the nucleon is done with a different approach to the evaluation of the bilocal contributions and to the extraction of the nucleon pole residues. The result obtained is much more numerically stable which puts their conclusion that about half of the nucleon spin is carried by gluons on firmer ground.
The evaluation of sum rules and vacuum condensates used in the calculation of the mixing parameters of the $ω-ρ$ system involve dangerous cancellations of large numbers. In this note the contribution of the continuum is eliminated in order to avoid such a large source of uncertainty. It is also seen that the hypothesis of vacuum saturation used in the estimate of the dimension 6 condensate is inadequate. The value obtained for the parameter $β$ which governs the off-shell variation of the $ω-ρ$ mixing is $β=.25$.