Transition magnetic moment ofΛ→Σ0in QCD sum rules

Abstract

The Λ → Σ 0 transition magnetic moment is computed in the QCD sum rules approach. Three independent tensor structures are derived in the external field method using generalized interpolating fields. They are analyzed together with the Λ and Σ 0 mass sum rules using a Monte-Carlo-based analysis, with attention to OPE convergence, ground-state dominance, and the role of the transitions in the intermediate states. Relations between sum rules for magnetic moments of Λ and Σ 0 and sum rules for transition magnetic moment of Λ → Σ 0 are also examined. Our best prediction for the transition magnetic moment is µ Σ 0 Λ = 1.60±0.07 µN . A comparison is made with other calculations in the literature.

Determination of the Σ-Λ mixing angle from QCD sum rules

“…So the problem of determination of the mixing angle requires the calculation of the theoretical part of the correlation function, for which the expressions of the interpolating currents are needed. According to the SU(3) f classification the interpolating currents for the unmixed Λ 0 and Σ 0 are chosen as [10,11],…”

“…This difference usually changes in the range between 0.3-0.8 GeV. It follows from the analysis of the mass sum rules that in order to reproduce the experimental values of the masses of the Σ and Λ baryons, the continuum threshold s 0 should lie in the range 2.5 GeV 2 ≤ s 0 ≤ 3.2 GeV 2 [10,11].…”

“…This difference usually changes in the range between 0.3-0.8 GeV . It follows from the analysis of the mass sum rules that in order to reproduce the experimental values of the masses of the Σ and Λ baryons, the continuum threshold s 0 should lie in the range 2.5 GeV 2 ≤ s 0 ≤ 3.2 GeV 2 [8,9]. Moreover, the working region of the Borel mass parameter should be such that, the results for the Σ-Λ mixing angle should exhibit good stability with respect to the variation of M 2 at fixed values of s 0 .…”

Magnetic moment for the negative parity Λ → Σ 0 transition in light cone QCD sum rules

“…These amplitudes appear when the matrix elements of the nonlocal operators are sandwiched between the vacuum and one-particle states (about the details of the LCSR see [5]). The magnetic moment of the Λ → Σ 0 transition has already been calculated in framework of the traditional QCD sum rules [6], the external field method in the traditional QCD sum rules [7], and in the light cone version of the QCD sum rules method [8]. Note that the magnetic moments of the negative parity octet baryons, J P = 3 − /2 heavy baryons, as well as diagonal and transition magnetic moments of negative party heavy baryons are calculated within the same framework in [9], [10] and [11], respectively.…”