Positive and NegativeParity Baryons in Coupled QCD Sum Rules
Abstract
We apply the method of the QCD sum rule, in which positive and negativeparity baryons couple with each other, to the flavoroctet baryons and investigate the parity splittings. The obtained sum rules turn out to have a very good Borel stability and also have a Borel window. The predicted masses of the positive and negativeparity baryons reproduce the experimental ones fairly well in the Λ and Σ channels, if we assign the Λ(1670) and the Σ(1620) to the parity partners of the Λ and the Σ, respectively. This implies that the Λ(1405) is not the party partner of the Λ and may be a flavorsinglet or exotic state. In the Ξ channel, the sum rule predicts the mass of the negativeparity state to be about 1.8~GeV, which leads to two possibilities; one is that the observed state, Ξ(1690), is the parity partner and the other is that the parity partner is not yet found but exists around 1.8~GeV.
 Publication:

Progress of Theoretical Physics Supplement
 Pub Date:
 2007
 DOI:
 10.1143/PTPS.168.50
 Bibcode:
 2007PThPS.168...50K