It is shown that in the constituent quark model of Georgi-Manohar, the dispersion relation that leads to the Adler- Weisberger sum rule for the axial vector coupling gA requires a subtraction constant. This fact explains the discrepancy between the results of different recent estimates of the 1 Nc corrections to Weinberg's large Nc result gA = 1, where Nc is the number of QCD colours. We also discuss a possible scenario which shows that gA = 1 might not be a necessary consequence of QCD in the large Nc limit. © 1993.
|Journal||Physics Letters B|
|Publication status||Published - 15 Jul 1993|