Magas V K, Oset E, Ramos A
Departamento de Física Teórica and IFIC, Centro Mixto, Institutos de Investigación de Paterna-Universidad de Valencia-CSIC, Apartado correos 22085, 46071, Valencia, Spain.
Phys Rev Lett. 2005 Jul 29;95(5):052301. doi: 10.1103/PhysRevLett.95.052301. Epub 2005 Jul 28.
The K- p --> pi0pi0sigma0 reaction is studied within a chiral unitary model. The distribution of pi0sigma0 states forming the lambda(1405) shows, in agreement with a recent experiment, a peak at 1420 MeV and a relatively narrow width of gamma = 38 MeV. The mechanism for the reaction is largely dominated by the emission of a pi0 prior to the K- p interaction leading to the lambda(1405). This ensures the coupling of the lambda(1405) to the K- p channel, thus maximizing the contribution of the second state found in chiral unitary theories, which is narrow and of higher energy than the nominal lambda(1405). This is unlike the pi- p --> K0pisigma reaction, which gives more weight to the pole at lower energy and with a larger width. The data of these two experiments, together with the present theoretical analysis, provide firm evidence of the two-pole structure of the lambda(1405).
在一个手征幺正模型中研究了K⁻p→π⁰π⁰σ⁰反应。形成Λ(1405)的π⁰σ⁰态的分布与最近的一个实验一致，在1420 MeV处有一个峰，且相对较窄的宽度Γ = 38 MeV。该反应机制在很大程度上由在导致Λ(1405)的K⁻p相互作用之前发射一个π⁰主导。这确保了Λ(1405)与K⁻p通道的耦合，从而使在手征幺正理论中发现的第二个态的贡献最大化，该态窄且能量高于标称的Λ(1405)。这与π⁻p→K⁰πσ反应不同，后者赋予较低能量且宽度较大的极点更大权重。这两个实验的数据，连同目前的理论分析，为Λ(1405) 的双极点结构提供了确凿证据。
