The QCD spectral sum rules in the presence of the external electromagnetic field F µν is used to calculate the magnetic moment of Σ c and Λ c . Our result

The method of QCD sum rules in the presence of the external electromagnetic

We use the method of QCD sum rules in the presence of an external pion field to investigate isospin symmetry breakings in pionnucleon couplings. Possible manifestations of such isospin symmetry breaking are examined in the context of low-energy nucleonnucleon (NN) scattering. We discuss numerical results in relation to both the existing data and other theoretical predictions.

The method of QCD sum rules in the presence of the external electromagnetic F µν field is used to calculate the Ω magnetic moment µ Ω and the Σ 0 Λ transition magnetic moment µ Σ 0 Λ , with the susceptibilities obtained previously from the study of octet baryon magnetic moments. The results µ Ω = −1.92µ N and µ Σ 0 Λ = 1.5µ N are in good agreement with the recent experimental data.Keywords: magnetic moment, QCD sum rules PACS: 13.40. Em, 14.20.Jn, 12.38.Lg According to the quark model the Ω − is composed of three strange quarks with parallel spins. This state is particularly interesting because of the large symmetry breaking that can not be accomodated consistently in the naive quark model. In Ref.[1], it has been shown that nonstatic baryon-dependent magnetic effects are large. In this paper we investigate these symmetry breaking effects and evaluate the Ω moment in the QCD sum rule [3]. The Ω moment has been studied in literaures [2] and various theoretical results range from −1.3µ N to −2.7µ N . We find our result is in good agreement with the recent data [4,5].In a typical hadronic scale the quantum chromodynamics (QCD) is highly nonperturbative which makes a direct analytical first-principle calculation impossible. In this work we adopt the method in the presence of an external electromagnetic field [6,7]

We calculate the on-shell ⌺ 0 -⌳ mixing parameter with the method of the QCD sum rule. Our result is (m ⌺ 0 2 )ϭ(Ϫ)(0.5Ϯ0.1) MeV. The electromagnetic interaction is not included. ͓S0556-2821͑98͒03103-8͔