Scalar Meson f0(980) Photoproduction in γp→pf0(980) Reaction
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摘要: 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).Abstract: 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).-
Key words:
- photoproduction process /
- scalar meson /
- feynman propagator
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