1/Nc expansion and the spin-flavor structure of the quark interaction in the constituent quark model

Abstract

We study the hierarchy of the coefficients in the 1/Nc expansion for the negative parity L=1 excited baryons from the perspective of the constituent quark model. This is related to the problem of determining the spin-flavor structure of the quark interaction. The most general two-body scalar interaction between quarks contains the spin-flavor structures $t_1^a{t}_2^a,{\vec{s}}_1\cdot {\vec{s}}_2$ and ${\vec{s}}_1\cdot {\vec{s}}_2{t}_1^a{t}_2^a$. We show that in the limit of a zero range interaction all these structures are matched onto the same hadronic mass operator $S_c^2$, which gives a possible explanation for the dominance of this operator in the 1/Nc expansion for the L=1 states and implies that in this limit it is impossible to distinguish between these different spin-flavor structures. Modeling a finite range interaction through the exchange of a vector and pseudoscalar meson, we propose a test for the spin-flavor dependence of the quark forces. For the scalar part of the quark interaction we find that both pion exchange and gluon exchange are compatible with data.

20 pages, 4 figures

References in corpus (6)

• The Physics of Glueballs
• Baryonic mass formula in large $N_c$ QCD versus quark model
• Analysis of Negative Parity Baryon Photoproduction Amplitudes in the $1/N_c$ Expansion
• The permutation group S_N and large Nc excited baryons
• Mass formula for strange baryons in large $N_c$ QCD versus quark model
• Quark Forces from Hadron Spectroscopy

Cited by in corpus (1)

• Testing for three-body quark forces in L=1 excited baryons