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Study of Electric Polarizabilities of Nucleon with a Constituent Quark Model and Pion Meson Cloud

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Communications in Theoretical Physics 2006年第5期45卷 885-888页

作者： dong yu-bing Institute of High Energy Physics the Chinese Academy of Sciences Beijing 100049 China

In this work, a subtle role of the pion meson cloud effect on the electric polarizabilities of the proton and neutron is stressed. It is shown that the electric polarizabilities of the proton and neutron, and the difference between the electric polarizabilities of the proton and neutron can be explained by including the pion meson cloud explicitly. However, the magnitude of the estimated mean-square charge radius of the neutron is still far from the measurement.

关键词： electric polarizability pion meson cloud charge radius

氮肥调控对紫云英-水稻轮作系统结瘤固氮特征及生产力的影响

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植物营养与肥料学报 2024年第1期30卷 1-11页

作者：张军倩董玉兵焦颖王冰雪王琛源宋梦馨熊正琴南京农业大学资源与环境科学学院/江苏省低碳农业与温室气体减排重点实验室江苏南京210095 江苏省农业科学院江苏徐淮地区淮阴农业科学研究所江苏淮安223001

[目的]研究不同水平氮肥管理对绿肥季共生固氮、固氮酶活性及后茬单季稻养分吸收和产量的综合影响。[方法]本试验以长期紫云英-水稻轮作系统为研究对象,设置4个处理:水稻-冬闲-NO (RF-N0)、水稻-紫云英-NO (RM-N0)、水稻-紫云英-N1 (RM-... 详细信息

[目的]研究不同水平氮肥管理对绿肥季共生固氮、固氮酶活性及后茬单季稻养分吸收和产量的综合影响。[方法]本试验以长期紫云英-水稻轮作系统为研究对象,设置4个处理:水稻-冬闲-NO (RF-N0)、水稻-紫云英-NO (RM-N0)、水稻-紫云英-N1 (RM-N1)、水稻-紫云英-N2 (RM-N2),NO、N1、N2分别代表绿肥季施用NO、50、100 kg/hm^(2),水稻季则统一施入N200 kg/hm^(2)。进行两个轮作周期的田间试验,测定紫云英季植株氮吸收量、根瘤量、根瘤固氮酶活性及水稻季植株氮吸收、籽粒产量和品质。[结果]在绿肥季,RM-N0处理紫云英两年平均共生固氮量达N 78.3 kg/hm^(2),共生固氮率高达91.1%。与RM-N0处理相比,RM-N1和RMN2处理两年平均固氮量分别减少6.5%和50.8%,共生固氮率分别降低22.1%和72.1%。配施氮肥改善了根瘤固氮酶活性,但配施高量氮肥显著降低了紫云英根瘤重量。RM-N0处理紫云英氮吸收量为N 86.0 kg/hm^(2),与之相比,RM-N1和RM-N2处理紫云英两年平均氮吸收量分别提高25.5%和62.7%。与RF-N0处理相比,RM的3个处理水稻产量2021年提高了6.1%~10.8%,2022年提高了6.7%~10.9%。与RF-N0相比,RM-N1和RMN2处理水稻籽粒蛋白质含量分别显著提高了11.5%和21.5%,籽粒直链淀粉含量和食味值则无显著变化。与RF相比,RM的3个处理均显著抑制杂草生长,改善土壤全氮含量。紫云英根际土壤RM-N0处理AOA基因拷贝数最大,RM-N2处理AOB基因拷贝数最大,RM-N1处理nifH基因拷贝数最大。[结论]种植并翻压紫云英可显著抑制杂草生长,增加水稻产量,改善水稻品质。紫云英施用氮肥可提高其氮吸收量,改善固氮酶活性;低氮肥用量还可显著提高根瘤生物量,显著增加土壤中nifH基因拷贝数。因此,在水稻-紫云英轮作系统,紫云英季施用N 50 kg/hm^(2)可显著提升绿肥对水稻的增产提质效果,提高土壤生产力。

关键词：紫云英单季稻共生固氮固氮酶活性水稻产量水稻品质

Electromagnetic Properties of S11 States in a Light Cone Quark Model

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Communications in Theoretical Physics 2006年第2X期46卷 269-274页

作者： HE Jun dong yu-bing Institute of High Energy Physics the Chinese Academy of Sciences P.O. Box 918-4 Beijing 100049 China Graduate School of the Chinese Academy of Sciences Beijing 100049 China

Using relativistic spin-flavor wave functions of a Lorentz-covariant light cone quark model, we calculate the electromagnetic form factors of two S11 resonances, N（1535） and N（1650）, and the helicity amplitudes A1/2 and S1/2 for electroexcitation of the S11 resonances from the nucleon. The electromagnetic form factors of these S11 resonances are found to be similar to those of the nucleon in shape, while the charge form factor of neutral N（1650） is nearly zero. The relative peak height of the S11 charge form factors is controlled by the mixing angle common to both resonance wave functions. As in most quark models, there is a systematic overestimate of A1/2 in both N（1535） and N（1650） cases at the photon point. A sizeable S1/2 for all cases is produced as suggested by experiments.

关键词： electromagntic properties S11 states light cone quark model

Pion Cloud Effects on △-N Mass Splitting from Quark Models

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Communications in Theoretical Physics 2002年第8期38卷 189-194页

作者： dong yu-bing FENG Qing-Guo Institute of High Energy Physics the Chinese Academy of Sciences P.O. Box 918-4 Beijing 100039 China Institute of High Energy Physics the Chinese Academy of Sciences P.O. Box 918-4 Beijing 100039 China

Pion cloud effects on △-N mass splitting are studied based on quark models. Pseudo-scalar pion-quarkcoupling is discussed in the relativistic and nonrelativistic frameworks. We separately calculate the pion cloud effects bythe one-pion exchange potential and by another method which is consistent with the baryon chiral perturbation *** able discrepancy in the mass splitting between the two methods is shown.

关键词： quark models, coupling constants, pion cloud, △-N mass splitting

Two-Photon Exchange Corrections to Single Spin Asymmetry of Neutron and 3He

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Communications in Theoretical Physics 2011年第3期55卷 489-494页

作者： CHEN Dian-Yong dong yu-bing Research Center for Hadron and CSR Physics Lanzhou University ＆ Institute of Modern Physics of CAS Lanzhou 73000 China Institute of Modern Physics Chinese Academy of Science Lanzhou 730000 China Institute of High Energy Physics Chinese Academy of Science Beijing 100049 China Theoretical Physics Center for Science Facilities Chinese Academy of Science Beijing 100049 China

In a simple hadronie model, the two-photon exchange contributions to the single spin asymmetries for the nucleon and the 3He are estimated. The results show that the elastic contributions of two-photon exchange to the single spin asymmetries for the nucleon are rather small while those for the 3He are relatively large. Besides the strong angular dependence, the two-photon contributions to the single transfer. spin asymmetry for the 3He are very sensitive to the momentum

关键词： simple hadronic model two-photon exchange single spin asymmetry

Nucleon Form Factors and N-△ Transitions in a Hypercentral Constituent Quark Model with Meson Cloud

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Communications in Theoretical Physics 2007年第3期47卷 539-546页

作者： CHEN Dina-Yong dong yu-bing Institute of High Energy Physics the Chinese Academy of Sciences Beijing 100049 China Gradtuate School of the Chinese Academy of Sciences Beijing 100049 China

We study the nucleon form factors and the nucleon-△（1232） transitions in a framework of hypercentral constituent quark model. The pion meson cloud effect is taken into account explicitly. Our results show that the pion cloud contributes substantially to the nucleon form factors as well as to the helicity amplitudes of △（1232）, and it gives an improved agreement compared to the experimental.

关键词： electromagnetic form factor nucleon and △(1232) hypercentral constituent quark model meson cloud

Electroproduction of Roper Resonance in a Meson Cloud Model

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Communications in Theoretical Physics 2008年第7期50卷 142-148页

作者： CHEN Dian-Yong dong yu-bing Institute of High Energy Physics the Chinese Academy of Sciences Beijing 100049 China

The Q^2 dependencies of Roper resonance (N~* (1440)) helicity amplitudes have been discussed based on twoassumptions:(i) the Roper resonance is an excitation of one of the three quarks,and (ii) the quarks are surrounded bya pion-meson *** study shows that the mixing of the ground state in the Roper wavefunction caused by the pionmeson cloud together with the pion meson cloud itself is crucial for the predictions of the photoproduction amplitudesof the Roper *** is found that our model can give a good description for the helicity amplitudes of the Roperresonance comparing with the experimental measurement.

关键词： photo-production amplitudes Roper resonance meson cloud

Meson Cloud Effect on △(1232) Resonance Transition Properties with a Relativistic Quark Model Approach

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Communications in Theoretical Physics 2002年第7期38卷 53-58页

作者： dong yu-bing FENG Qing-Guo Institute of High Energy Physics Academia Sinica P.O. Box 9184-1 Beijing 100039 China Institute of High Energy Physics Academia Sinica P.O. Box 9184-1 Beijing 100039 China

Based on a relativistic quark model approach, the transition properties of the first nucleon resonance △(1232), and the coupling constants gπNN, g△πN are investigated. Tvo different vays to remove the center of mass motion are considered. The results of the relativistic approaches with and without center ofmass correction are compared with those of nonrelativistic constituent quark model. Moreover, pion meson cloud effect on these calculated observables is explicitly addressed. Better results are obtained by taking the pion meson cloud into account.

关键词： relativistic quark model, △(1232), coupling constants, meson cloud, decay width

Heavy Quarkonium Spectra in a Quark Potential Model

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Chinese Physics Letters 2001年第12期18卷 1558-1560页

作者： CHEN Hong ZHANG Jingg dong yu-bing SHEN Peng-Nian Department of Physics Southwest China Normal UniversityChongqing 400715 Institute of High Energy Physics Chinese Academy of SciencesBeijing 100039

By solving the eigenvalue equation for the quark-antiquark potential which emerges from an effective dilatongluon coupling inspired by superstring theory, we obtain the spin-averaged energy levels of charmonium (cc) and bottonium (bb) and show that the masses of the cc and bb states are well in agreement with the available experimental data.

关键词： quark eigenvalue averaged