The $[\bf{56},4^+]$ baryons in the $1/N_c$ expansion

Abstract

Using the $1/N_c$ expansion of QCD we analyze the spectrum of positive parity resonances with strangeness $S = 0, -1, -2$ and -3 in the 2-3 GeV mass region, supposed to belong to the $[\textbf{56},4^+]$ multiplet. The mass operator is similar to that of $[\textbf{56},2^+]$, previously studied in the literature. The analysis of the latter is revisited. In the $[\textbf{56},4^+]$ multiplet we find that the spin-spin term brings the dominant contribution and that the spin-orbit term is entirely negligible in the hyperfine interaction, in agreement with constituent quark model results. More data are strongly desirable, especially in the strange sector in order to fully exploit the power of this approach.