Chiral Lagrangians with $\Delta (1232)$ to one loop

Abstract

We construct the Lorentz-invariant chiral Lagrangians up to the order $\mathcal{O}(p^4)$ by including $\Delta (1232)$ as an explicit degree of freedom. A full one-loop investigation on processes involving $\Delta (1232)$ can be performed with them. For the $\pi \Delta \Delta$ Lagrangian, one obtains 38 independent terms at the order $\mathcal{O}(p^3)$ and 318 independent terms at the order $\mathcal{O}(p^4)$. For the $\pi N\Delta$ Lagrangian, we get 33 independent terms at the order $\mathcal{O}(p^3)$ and 218 independent terms at the order $\mathcal{O}(p^4)$. The heavy baryon projection is also briefly discussed.

Comments: 23 pages,8 tables. Less terms are found with more constraints. Version accepted by PRD