coupling constant

We calculate the π∆∆ coupling gπ0∆++∆++ using light cone QCD sum rule. Our result is gπ0∆++∆++ = (11.8 ± 2.0). We compare various model predictions. PACS numbers: 12.39.Fe, 14.20.Gk The π∆∆ coupling constant g1, like the nucleon axial charge gA, is a basic parameter which enters the loop calculation in all processes involved with delta resonance [1] in chiral perturbation theory. Unfortunately it is not directly accessible experimentally. In a recent letter [2] Jido et al. proposed a special quartet scheme of chiral symmetry realization for evenand odd-parity baryon resonances. Based on their specific scheme they concluded that the parity nonchanging couplings such as π∆±N ∗ ± , π∆±∆±, and πN ∗ ± N ± are forbidden. Such a result is in strong contrast with quark model prediction [3] and large Nc argument g1 = 9 5 gA [4]. So an independent theoretical extraction will prove useful to clarify the present ambiguous situation concerning this coupling. We have calculated πNN and πNN [5], ηNN [6] and ρNN , ωNN [7] coupling constants in the framework of light cone QCD sum rule (LCQSR). The extracted values of various couplings from LCQSR are in good agreement with those used in or obtained from phenomenological analysis. In this short note we extend the same formalism to calculate the π∆∆ coupling constant. Let’s first introduce some notations. For the ∆ resonance, we use the isospurion formalism, treating the ∆ field T i μ(x) as a vector spinor in both spin and isospin space with the constraint τ T i μ(x) = 0. The components of this field are T 3 μ = − √