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Decay width of d (2380) ! NN process in a chiral constituent quark model

Yubing Dong; Fei Huang; Pengnian Shen; Zongye ZhangSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The width of three-body single-pion decay process d? → NNπ0,± is calculated by using the d? wave function obtained from our chiral SU(3) constituent quark model calculation. The e?ect of the dynamical structure on the width of d? is taken into account in both the single ?? channel and cou-pled ??+CC two-channel approximations. Our numerical result shows that in the coupled-channel approximation, namely, the hidden-color con?guration being considered, the obtained partial decay width of d? → NNπ is about several hundred KeV, while in the single ?? channel it is just about 2 ? 3 MeV. We, therefore, conclude that the partial width in the single-pion decay process of d? is much smaller than the widths in its double-pion decay processes. Our prediction may provide a criterion for judging di?erent interpretations of the d? structure, as di?erent pictures for the d? may result quite di?erent partial decay width. |

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

F. Huang; P. N. Shen; Y. B. Dong; Z. Y. ZhangSubjects: Physics >> Nuclear Physics

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(JP)=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?→dπ0π0?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. |

A study of the $d^*(2380) \to d \pi \pi$ decay width

Yubing Dong; Pengnian Shen; Fei Huang; Zongye ZhangSubjects: Physics >> Nuclear Physics

The decay widths of the?$\ds\to d \pi^0\pi^0$?and?$\ds\to d \pi^+\pi^-$?processes are explicitly calculated in terms of our chiral quark model. By using the experimental ratios of cross sections between various decay channels, the partial widths of the?$\ds\to pn \pi^0\pi^0$,?$\ds\to pn \pi^+\pi^-$,?$\ds\to pp \pi^0\pi^-$, and?$\ds\to nn \pi^+\pi^0$?channels are also extracted. Further including the estimated partial width for the?$\ds\to pn$?process, the total width of the?$\ds$resonance is obtained. In the first step of the practical calculation, the effect of the dynamical structure on the width of$\ds$?is studied in the single?ΔΔ?channel approximation. It is found that the width is reduced by few tens of MeV, in comparison with the one obtained by considering the effect of the kinematics only. This presents the importance of such effect from the dynamical structure. However, the obtained width with the single?ΔΔ?channel wave function is still too large to explain the data. It implies that the?$\ds$?resonance will not consist of the?ΔΔ?structure only, and instead there should be enough room for other structure such as the hidden-color (CC) component. Thus, in the second step, the width of?$\ds$?is further evaluated by using a wave function obtained in the coupled?ΔΔ?and CC channel calculation in the framework of the Resonating Group Method (RGM). It is shown that the resultant total width for?$\ds$?is about 69 MeV, which is compatible with the experimental observation of about 75 MeV and justifies our assertion that the?$\ds$?resonance is a hexaquark-dominated exotic state. |

Decay width of $d^*(2380)\to NN \pi\pi$ processes

Yubing Dong; Fei Huang; Pengnian Shen; Zongye ZhangSubjects: Physics >> Nuclear Physics

The decay widths of four-body double-pion decays?$\ds\to pn \pi^0\pi^0$,?$\ds\to pn \pi^+\pi^-$, and iso-scalar parts of?$\ds\to pp \pi^0\pi^-$?and?$\ds\to nn \pi^+\pi^0$?are explicitly calculated with the help of the?d??wave function obtained in a chiral SU(3) quark model calculation. The effect of the dynamical structure on?$\ds$'s width is analyzed both in the single?ΔΔ?channel and coupled?ΔΔ?and?CC?channel approximations. It is found that in the coupled-channel approximation, the obtained partial decay widths of?$\ds\to pn \pi^0\pi^0$,?$\ds\to pn \pi^+\pi^-$, and those of?d??to the iso-scalar parts of?ppπ0π??and?nnπ+π0?are about?7.4MeV,?16.4MeV,?3.5MeV and?3.5MeV, respectively As a consequence, the total width is about?64.5MeV. These widths are consistent with those estimated by using the corresponding cross section data in our previous investigation and also the observed data. But in the single?ΔΔ?channel approximation, the widths are still almost 2-times larger than the measured values. Apparently, the explicitly calculated width together with the evaluated mass of?d??in the coupled?ΔΔ?and?CC?channel approximation can well explain the observed data, which again supports our assertion that the?$\ds$resonance is a six-quark dominated exotic state. |

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