Electromagnetic structure of the low-lying baryons in covariant chiral perturbation theory

Abstract

We report a calculation of the low-lying baryon magnetic moments using covariant chiral perturbation theory within the extended-on-mass-shell renormalization scheme including intermediate octet and decuplet contributions. For the case of the baryon octet, we succeed to improve the Coleman-Glashow description by including the leading SU(3)${}_F$-breaking effects coming from the lowest-order loops. We compare with previous attempts at the same order using heavy-baryon and covariant infrared chiral perturbation theory, and discuss the source of the differences. For the case of the decuplet-baryons we fix the only unknown LEC with the well measured magnetic dipole moment of the ${\Omega }^{-}$ and predict the corresponding ones of the $\Delta (1232)$ isospin multiplet. In particular we obtain ${\mu }_{{\Delta }^{++}}=6.0(6){\mu }_N$ and ${\mu }_{{\Delta }^{+}}=2.84(34){\mu }_N$ that compare well with the current experimental information.

Comments: Proceedings-6th International Workshop on Chiral Dynamics-CD09 July 6-10, 2009-Bern, Switzerland