Scalar form factors in SU(3) chiral perturbation theory

Abstract

The scalar form factors for the pions and kaons are calculated in SU(3) Chiral Perturbation Theory at order $p^6$, in the isospin limit $m_u=m_d=\hat{m}$. We find in general sizable corrections of $\mathcal{O}(p^6)$. We use our results to obtain results on the $1/N_c$ suppressed low energy constants $L_4^r$ and $L_6^r$ as well as on two $\mathcal{O}(p^6)$ low energy constants. We present some numerical results for masses and decay constants as well. We derive a relation for the scalar form factors analogous to Sirlin's relation for vector form factors.