Resummation Study on Decay $ρ\toππ$ in $U(2)_L\times U(2)_R$ Chiral Theory of Mesons

Abstract

We improve $O(p^4)$ calculation in $U(2)_L\times U(2)_R$ chiral theory of mesons by resummation calculation for vector mesons physics and restudy decay $ρ\toππ$. A complete and compact expression for $f_{ρππ}(p^2)$ (up to $O(p^\infty)$) is obtained, from which an important non-perturbative conclusion is given based on convergence and unitarity consideration.