分类： 物理学 >> 核物理学 提交时间： 2023-11-14
Yijie Wang
Fenhai Guan
Dawei Si
Sheng Xiao
Boyuan Zhang
Yaopeng Zhang
Baiting Tian
Xianglun Wei
Herun Yang
Peng Ma
Rongjiang Hu
Limin Duan
Fangfang Duan
Qiang Hu
Junbing Ma
Shiwei Xu
Zhen Bai
Yanyun Yang
Jiansong Wang
Wenbo Liu
摘要： Two-body correlations of the isotope-resolved light and heavy clusters are measured in 86Kr+ 208Pb reactions at 25 MeV/u. The yield and kinetic variables of the A = 3 isobars, triton and 3He, are analyzed in coincidence with the heavy clusters of 7 A 14 emitted at the earlier chance. While the velocity spectra of both triton and 3He exhibit scaling behavior over the type of the heavy clusters, the yield ratios of t/ 3He correlate reversely to the neutron-to-proton ratio N/Z of the latter, showing the ping-pong modality of the N/Z of emitted clusters. The commonality that the N/Z of the residues keeps the initial system value is extended to the cluster emission in heavy ion reactions. The comparison of transport model calculations to the data is discussed.
分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间： 2017-11-10
摘要： 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 effect 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 configuration 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 different interpretations of the d∗ structure, as different pictures for the d∗ may result quite different partial decay width.
分类： 物理学 >> 核物理学 提交时间： 2016-09-13
摘要： 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.
分类： 物理学 >> 核物理学 提交时间： 2016-09-13
摘要： 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.
分类： 物理学 >> 核物理学 提交时间： 2016-09-01
摘要： 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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