d^′dibaryon in a colored cluster model

Abstract

The mass and wave function of a six-quark system with quantum numbers J P =0 − , T=0, called d ′ , are calculated. We use a colored diquark-tetraquark cluster model for the six-quark wave function. A constituent quark model Hamiltonian with a two-body confinement potential, and residual one-gluon, one-pion, and one-sigma exchange interactions is used. The complications due to the quark exchange interactions between tetraquark and diquark clusters (Pauli principle) are taken into account within the framework of the Resonating Group Method. The calculated d ′ mass is some 350 MeV above the empirical value if the same two-body confinement strength as in the nucleon and ∆ is used. This paper also examines the validity of the usual assumption of a universal two-quark confinement strength. We propose that the effective two-body confinement strength in an exotic six-quark system, such as the d ′ , could be weaker than in a single baryon. The weaker confinement hypothesis leads to a d ′ mass of M d ′ = 2092 MeV and a d ′ radius of r d ′ = 1.53 fm.

Dynamical calculation of theΔΔdibaryon candidates

“…A worldwide theoretical and experimental effort to search for dibaryon states with and without strangeness lasts for a long time. The S = 0, J P = 0 − d ′ dibaryon, which is hard to be explained by quark models [4], was claimed by experiments in 1993 and disappeared years later [5]. Our group showed that the S = 0, I = 0, J = 3 d * is a tightly bound sixquark system rather than a loosely bound nucleus-like system of two ∆s [6][7][8][9].…”

Quark delocalization, color screening model and nucleon–baryon scattering

“…[7]. Recently, the proposed d ′ (IJ P = 00 − ) dibaryon has been studied by Faessler's group [8] , who concluded that both bag and hybrid meson-gluon exchange models cannot obtain such a state with a mass as low as 2.06GeV. If the d ′ is proven to exist, that will argue strongly against the completeness of these models.…”

Quark-model study of few-baryon systems

“…The possible existence of unstable non-strange two-and three-baryon resonances corresponding to bound-state solutions of systems composed of nucleons and deltas has been speculated for years [217][218][219][220][221][222][223][224][225][226]. In the case of two-body systems (that we shall refer to as dibaryons) they will decay mainly into two nucleons and either one or two pions, while for the three-body case (tribaryons) they will decay mainly into three nucleons and either one, two, or three pions.…”