上广电DVD-2380 试用纪实

以前很长一段时间,我对国产器材的品质不大信得过.倒不是崇洋媚外,早期我也曾买过几款国产器材,但总是感到不甚满意,没有多久就会出现一些小毛病,使人后悔不已.所购的进口器材则要好得多,突出的便是可靠性高,让人买得放心,用得放心.不过,近来情况有些反常,不知怎么搞的,家里多件正宗进口的洋器材纷纷在闹罢工.录像机、LD机姑且算是年久失修,行将退役;WALKMAN没怎么用,闲置数月就产生自激啸叫,这固然是因为微型电解电容器容易干涸失效所致,也不说它了.可是,几件购置两年左右的名牌产品出现的故障就有些说不过去了:Hi-Fi功放的音源选择开关接触不良;AV功放有几个声道的输出时有时无;CD机先是出盒不正常,最后主轴电机停转.于是乎我对进口器材的可靠性也产生了怀疑,至少现在可靠性不会再影响我的选择了.

Constituent counting rule and the production of d~*(2380) at high energies

The constituent counting rule, determining the scaling behavior of the transition amplitudes in an exclusive process at high energies, is applied to probe the internal structure of the newly observed d*(2380) resonance. Several selected exclusive processes at high energies for the production of d* are discussed. Results of two structural scenarios for d*(2380), a hexaquark dominant compact system in the quark degrees of freedom, and a threebody bound state in the hadronic degrees of freedom, are analyzed and compared. A rather remarkable difference between the results of these two scenarios for the mentioned processes are addressed.

On the decays of d^＊(2380) in a constituent chiral quark model

After summarizing the experimental results and present status of the d^＊（2380） observed at WASA@COSY,two “extreme” models for explaining its structure, a compact hexaquark dominated model and a loose △△＇-D_（12）π model, are briefly discussed, especially the former. By comparing their results with the corresponding data, the differences of the two models are addressed. As a remedy for the latter model, a mixing model and its result are also quoted for a comparison. It is shown that the compact hexaquark dominated structure might be more promising.However, the mixing model is also a possible structure, and more accurate Γ_（d^＊）→NN_π data are needed for confirmation.

Phenomenological study on the decay widths of Υ(nS)→d~*(2380)+X

The decay widths of Υ（nS）→d^＊（2380）＋X with n=1,2,3 are studied in a phenomenological way. With the help of crossing symmetry, the decay widths are obtained by investigating the imaginary part of the forward scattering amplitudes between d^＊ and Υ（nS）. The wave functions of d^＊ and deuteron obtained in previous studies are used for calculating the amplitude. The interaction between d^＊（d） and Υ is governed by the quark-meson interaction, where the coupling constant is determined by fitting the observed widths of Υ（nS）→d＋X. The numerical results show that the decay widths of Υ（nS）→d^＊＋X are about 2-10 times smaller than that of d＋X. The calculated momentum of d^＊ is in the range 0.3-0.8 GeV. Therefore, it is very likely that one can find d^＊（2380） in these semi-inclusive decay processes.

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

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 △△ and hidden-color channel （CC） with quantum numbers l（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＊ → dπ^0π^0 and d＊ → dn^＋n^- 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, F ≈ 70 MeV） reported by WASA-at-COSY Collaboration.

An estimate of dibaryon production in the process of pp→d^(∗)(2380)+pn at Panda facility

Although d∗(2380)was first observed by WASA@COSY,its existence has yet to be further confirmed in different types of processes at other facilities.In this work,the possible production of the single dibaryon state d^(∗)(2380)in the process of pp→d^(∗)(2380)pn in a future experiment at the Panda facility is estimated.Following the method used in our previous study(Chin.Phys.C 46,023105),a phenomenological Lagrangian approach is employed to study the single d^(∗)production.Based on the conclusions obtained by the non-relativistic constituent quark model,the cross section of the pp→d^(∗)(2380)pn reaction via the ΔΔ intermediate state is estimated,which is in the order of nb.It is shown that the dominant contribution comes from the diagram with the ΔΔ→pn subprocess.However,it is difficult to measure owing to the large background.Further,although the cross section of the diagram with the d^(∗)→pn subprocess is small,i.e.,only approximately 3%∼4% of the total cross section or even smaller,the corresponding number of events is still sufficiently large and can be measured at Panda because the outgoing p and n come from the same source d^(∗).

同方服务器方队:奠基于技术 崛起于应用

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产品

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敦煌写本S.2506V等《失名史书》疑难草书校释

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Possible dibaryon production at Panda with a Lagrangian approach

In order to confirm the existence of the dibaryon state d^(*)(2380)observed at WASA@COSY,we estimate the cross section for production of the possible dibaryon and anti-dibaryon pair d^(*)d^(*)in the energy region of the upcoming experiments at Panda.Based on some qualitative properties of d^(*)extracted from the analyses in the non-relativistic quark model,the production cross section for this spin-3 particle pair are calculated with the help of a phenomenological effective relativistic and covariant Lagrangian approach.