Understanding the structure of d*(2380) in chiral quark model

Abstract

The structure and decay properties of d * have been detailedly investigated in both the chiral SU(3) quark model and the extended chiral SU(3) quark model that describe the energies of baryon ground states and the nucleon-nucleon (NN) scattering data satisfactorily. By performing a dynamical coupled-channels study of the system of ΔΔ and hidden-color channel (CC) with quantum numbers I(J P ) = 0(3 + ) in the framework of the resonating group method (RGM), we find that the d * has a mass of about 2.38-2.42 GeV and a root-mean-square radius (RMS) of about 0.76-0.88 fm. The channel wave function is extracted by a projection of the RGM wave function onto the physical basis, and the fraction of CC component in the d * is found to be about 66%-68%, which indicates that the d * is a hexaquark-dominated exotic state. Based on this scenario the partial decay widths of d * → dπ 0 π 0 and d * → dπ + π − are further explicitly evaluated and the total width is then obtained by use of the branching ratios extracted from the measured cross sections of other possible decay channels. Both the mass and the decay width of d * calculated in this work are compatible with the data (M ≈ 2380 MeV, Γ ≈ 70 MeV) reported by WASA-at-COSY Collaboration. hexaquark state, d * (2380), quark model, hidden-color channel PACS number(s): 14.20.Pt, 13.75.Cs, 12.39.Jh, 13.30.Eg Citation:

Form factors of the d*(2380) resonance

“…With the assumption of such a structure, its mass was predicted [8]. In recent years, a series of sophisticated studies on the structure and decay properties of d à has further been performed, and a compact picture for it, an exotic hexaquark dominated state, was deduced [8,[10][11][12][13][14]39]. In order to get a meaningful result for a 6-quark system, those calculations were dynamically carried out on the quark degrees of freedom by using a chiral SU(3) constituent quark model.…”

“…Þη η ΔΔðC 8 C 8 Þ is the relative wave function between A and B clusters which will be determined by dynamically solving the RGM equation [10,11] …”

“…1 and Table I, one sees that comparing with corresponding D-waves, the S-wave in both ΔΔ, and C 8 C 8 channels are overwhelmingly dominant, and the D-waves are negligibly small. The probability of the S-wave in the C 8 C 8 channel is about 2 times larger than that in the ΔΔ channel which is essential for our understanding of the partial widths in the double-pion and singlepion decays of d à , and consequently of a narrow total width in our assumption of the compact structure of d à [10][11][12][13][14][15]39].…”

“…In our previous studies [8,[10][11][12][13][14][15], we enlarged the Fock space to involve the next lowest QCD allowed configuration, proposed the possible structure of d à as a hexaquark dominated state and dynamically calculated it in the framework of the resonating group method (RGM) with a trial wave function of the ΔΔ þ C 8 C 8 structure in the chiral SU(3) constituent quark model. It should be stressed that the approach can explain most of the data available on the masses of the ground states of baryons, the scattering and reaction data of the baryon-baryon interactions, the binding energy of the deuteron and even H particle, etc.…”

Shedding light on Hexaquarks

“…Calculations started with the pioneering work of Dyson and Xuong [9] in 1964 and have developed in many studies since then [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. Various configurations were suggested to describe the d * internal structure.…”