{"arxiv_id":"hep-ph/0503043","title":"Evidence for the two pole structure of the Lambda(1405) resonance","abstract":"The K^- p --> pi^0 pi^0 Sigma^0 reaction is studied within a chiral unitary model. The distribution of pi^0 Sigma^0 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 pi^0 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 --> K^0 \\pi Sigma 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, provides a firm evidence of the two pole structure of the Lambda(1405).","primary_cat":"hep-ph","cross_cats":[],"submitted_at":"2005-03-04T11:20:53+00:00","latest_version":1,"source":"arxiv","source_label":"arXiv","source_url":null,"has_pdf":true,"has_source":false,"verdict":"CONDITIONAL","confidence":"MODERATE","one_line_summary":"A chiral unitary calculation of K-minus proton to two neutral pions plus Sigma-zero reproduces the observed 1420 MeV peak and narrow width, which the authors read as evidence for the two-pole structure of the Lambda(1405).","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","upvotes":0,"downvotes":0,"pith_score":0,"inbound_count":13,"_links":{"html":"https://pith.science/paper/hep-ph/0503043","verdict":"/api/v1/verdicts/hep-ph/0503043"}}