Magnetic moment of the Ω− in QCD sumrule (QCDSR)

The Ω− magnetic moment (μΩ) was measured very accurately and it differs from most of the theoretical estimates, thus posing a challenge to the latter. There are two existing calculations of the magnetic moment [F. X. Lee, Phys.Lett. B 419 (1998) 14, hep-ph/9707411; S. Zhu, W. Y. P. Hwang and Z. Yang, Phys. Rev. D 57 (1998) 1527, hep/ph 9802322] using QCDSR. The first is a careful theoretical study which underestimates the (μΩ). We revisit this calculation, using condensate parameters which were obtained from fitting the differences (μp−μn), (μΣ+−μΣ−) and (μΞ0−μΞ−) [J. Dey, M. Dey and M. Sinha Roy, Phys. Lett. B 443 (1998) 293] and confirm the experimental number. The μΔ++ is also found to agree with the experimental estimate. We conclude that there is no discrepancy between experiment and theory. The second QCDSR calculation reports agreement with experimental (μΩ) and it is found that this is inconsistent with the octet baryon magnetic moment differences investigated by Dey et al. [J. Dey, M. Dey and M. Sinha Roy, Phys. Lett. B 443 (1998) 293] and is unreliable.