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41.
轻标量介子性质研究是当今中高能核物理研究中的热点问题之一,特别是质量低于1 GeV的标量介子f0(980)的内部结构一直存在争议,至今未达成共识。基于前人的研究结果,运用有效拉氏量方法,对f0(980)粒子的光生过程γp→pf0(980)进行了更深入的理论研究。探讨了两种传播子形式下得矢量介子ρ和ω交换的贡献,第一种是选择雷吉传播子,第二种是选择普通费曼传播子。第二种形式的微分散射截面理论结果与现有实验数据符合比第一种形式的结果好。基于此,计算了两种形式的总截面,两种形式给出的理论结果相差很大。另外,给出了γp→pf0(980)→pπ+π-过程的π+π-不变质量分布的理论预言,发现π+π-不变质量分布对于f0(980)于K-K的耦合常数(gf0KK)有很强的依赖关系,不同的gf0KK给出明显不同的π+π-不变质量分布。将来相关实验数据可以验证这些理论预言,并对矢量介子传播子形式和耦合常数gf0KK做出限制,加深人们对f0(980)粒子的认识。We study the scalar meson f0(980) in the γp→pf0(980) reaction within an effective Lagrangian approach. Based on previous studies, we calculate the differential cross sections of this reaction. We take two types of the propagators of vector mesons ρ and ω, one is the Regge form, the other one is the normal Feynman propagator. It is found that our theoretical results for the differential cross sections with the Feynman propagator are in agreement with the current experimental data. For the total cross sections, the results with the two types of propagator are much different. On the other hand, we predict the π+π- invariant mass distribution of the γp→pf0(980)→pπ+π- reaction. We find that the π+π- invariant mass distribution depends sensitively on the value of the coupling constant gf0KK. We hope that the future experiments can test our model calculation and give further constraints on the value of gf0KK and also the nature of f0(980). 相似文献
42.
By making use of the generating functional method we derive the Dyson-Schwinger equations in the NJL model and obtain the revised quark gap equation due to the meson dressing effects (usually called beyond the mean-field correction), and finally analyze its influence on the meson properties as well as the nucleon sigma term. 相似文献
43.
杨文熊 《应用数学和力学(英文版)》1995,16(1):27-35
GENERALIZEDTHEORYOFNONLINEARANDUNSTEADYMECHANICSANDAPPLICATIONSTOPARTICLEPHYSICSYangWen-xiong(杨文熊)(ShanghaiJiaotonyUniversity... 相似文献
44.
S.V. Golovkin A.P. Kozhevnikov V.P. Kubarovsky V.F. Kurshetsov L.G. Landsberg V.V. Molchanov V.A. Mukhin S.V. Petrenko V.A. Senko D.V. Vavilov V.A. Victorov V.Z. Kolganov G.S. Lomkatsi A.F. Nilov V.T. Smolyankin 《The European Physical Journal A - Hadrons and Nuclei》1999,5(4):409-416
New data for the diffractive reaction p+N→ [Σ0
K
+] +N at E
p= 70 GeV were obtained with partially upgraded SPHINX setup. The data are in a good agreement with the results of our previous
study of this reaction. In the mass spectrum M(Σ0
K
+) a structure at the threshold region with a mass ∼1810 MeV and a distinct X(2000) peak with M= 1989 ± 6 MeV and γ= 91 ± 20 MeV are observed. Unusual features of the massive X(2000) state (narrow decay width, anomalously
large branching ratio for the decay channel with strange particle emission) make it a serious candidate for cryptoexotic pentaquark
baryon with hidden strangeness |qqqsˉs>. We also present new results on the narrow threshold structure X(1810) with M= 1807 ± 7 MeV and γ= 62 ± 19 MeV which is produced in the region of very small P
2
T < 0.01 GeV2. The possibility of the Coulomb production mechanism for X(1810) is discussed.
Received: 28 April 1999 相似文献
45.
B. Krusche J. Ahrens R. Beck M. Fuchs S.J. Hall F. Härter J.D. Kellie V. Metag M. Röbig-Landau H. Ströher 《The European Physical Journal A - Hadrons and Nuclei》1999,6(3):309-324
Photoproduction of neutral pions from the deuteron has been studied for incident photon energies from 200 MeV to 792 MeV
with the TAPS detector at the Mainz MAMI accelerator. Total and differential cross sections covering the full angular range
have been obtained for coherent and incoherent single πo-photoproduction. Good agreement between model predictions and the data was found for the coherent process. The incoherent
cross section in the energy region of the Δ(1232)-resonance is overestimated by existing models. A comparison to model predictions
indicates that final state interaction effects are much more important than for the coherent reaction. However, the angular
dependence of the data in the Δ-peak region follows the pattern expected from the dominant excitation of the M1+-multipole on the free nucleon. The energy and angular dependence of single πo-photoproduction in the second resonance region is remarkably different from the reaction on the free proton, indicating a
strong nuclear effect. Finally the total cross section for double πo-photoproduction from the deuteron has been measured for the first time and was used to estimate the cross section for double
πo-photoproduction from the neutron.
Received: 24 June 1999 / Revised version: 30 August 1999 相似文献
46.
杨文熊 《应用数学和力学(英文版)》1999,20(3):276-281
IntroductionItiswell-knownthatanearallawalwaysdevelopsfromthelowertothehigher,andthatdescribingaquantitativescienceofthingessenceisalsofromthelinearitytothenonlinearity.In1995,theauthorexpandedthelinearmomentUmploftheNeWtonianmechanicstothenonlinearmomentumbyusingtheLaurentseries,andinwhichitisthesupernonlinearmomentUmincludingallnonlineartCrmsllj.Themomentumisthevectorterminthecombinatorialvector.u.bert2].Theauthorcallsthevelocityinthesupernonlinearmomentumasthesupernonlinearvelocity(somes… 相似文献
47.
We calculate inclusive light vector mesons (p,w, and φ) production in relativistic heavy ion collisions based on the idea of gluon saturation in the color glass condensate (CGC) framework. At high energies, the value of saturation momentum becomes larger than the Quantum Chromodynamics (QCD) confinement scale ΛQCD, which implies that s(Qs) << 1. Using the relativistic kinetic theory, we derive the production rate for the light vector mesons produced by gluon-gluon fusion in the kT -factorization approach. The numerical results indicate that the light vector mesons from the color glass condensate become prominent in p-p, p-Pb, and Pb-Pb collisions at Large Hadron Collider (LHC) energies. 相似文献
48.
Meson electro-magnetic form factors in an extended Nambu–Jona-Lasinio model including heavy quark flavors
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Based on an extended NJL model including heavy quark flavors, we calculate the form factors of pseudoscalar and vector mesons. After taking into account the vector-meson-dominance effect, which introduces a form factor correction to the quark vector coupling vertices, the form factors and electric radii of π+and K+pseudo-scalar mesons in the light flavor sector fit the experimental data well. The magnetic moments of the light vector mesonsρ+and K*+are comparable with other theoretical calculations. The form factors in the light-heavy flavor sector are presented to compare with future experiments or other theoretical calculations. 相似文献
49.
<正>This paper discusses the masses and possible members of 21S0 and 23S1 meson multiplets in the framework of meson-meson mixing and Regge phenomenology.For the 21S0 meson nonet,K*(1460) may be the observed state of the 21S0 isodoublet with a mass of 1400 MeV and the mass ofω(1420) is 1412 MeV.For the 23S1 meson nonet,K*(1410) seems too light to be the 23S1 ns member.The fact that the agreement between the present findings and those given by experiments and other different approaches is satisfactory implies that the assignments in this paper may be reasonable. 相似文献
50.
LI Hsiang-Nan 《中国物理C(英文版)》2009,33(6)
We explain the framework for calculating next-to-leading-order (NLO) corrections to exclusive processes in the kT factorization theorem, taking πγ→γ T as an example. Partons off-shell by k2T are considered in both the quark diagrams from full QCD and the effective diagrams for the pion wave function. The gauge dependences in the above two sets of diagrams cancel, when deriving the kT-dependent hard kernel as their difference. The light-cone singularities in the kT-dependent pion wave function are regularized by rotating the Wilson lines away from the light cone. Both the large double logarithms In2 kT and ln2x, x being a parton momentum fraction, arise from the loop correction to the virtual photon vertex, the former being absorbed into the pion wave function, and the latter into a jet function. 相似文献