The $[56,4^{+}]$ baryon multiplet in the $1/N_c$ expansion of QCD

Abstract

We use the $1/N_c$ expansion of QCD to 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 $[\text{56},4^{+}]$ multiplet. The mass operator is similar to that of $[\text{56},2^{+}]$, previously studied in the literature. The analysis of the latter is revisited. In the $[\text{56},4^{+}]$ 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.}

Comments: 12 pages, Talk given at the International Workshop on Large N_c QCD 2004, ECT*, Trento (Italy), July 5-9, 2004, to be published in World Scientific (Singapore) 2005, added reference, typos corrected