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Evidence for the two-pole structure of the lambda(1405) resonance.
1Departamento de Física Teórica and IFIC, Centro Mixto, Institutos de Investigación de Paterna-Universidad de Valencia-CSIC, Apartado correos 22085, 46071, Valencia, Spain.
Physical Review Letters
|August 11, 2005
Summary
The chiral unitary model study reveals the lambda(1405) resonance has a two-pole structure. This finding, supported by experimental data, clarifies the lambda(1405) resonance in K- p interactions.
Area of Science:
- Nuclear Physics
- Particle Physics
- Quantum Chromodynamics
Background:
- The lambda(1405) resonance is a key subject in hadron spectroscopy.
- Its internal structure and pole structure have been debated.
- Understanding its properties is crucial for advancements in nuclear and particle physics.
Purpose of the Study:
- To investigate the K- p --> pi0pi0sigma0 reaction using a chiral unitary model.
- To analyze the properties and structure of the lambda(1405) resonance.
- To provide theoretical evidence for the two-pole structure of the lambda(1405).
Main Methods:
- Utilizing a chiral unitary model for theoretical calculations.
- Analyzing the pi0sigma0 invariant mass distribution.
- Comparing theoretical predictions with experimental data from K- p and pi- p reactions.
Main Results:
- The study identified a peak at 1420 MeV with a narrow width (gamma = 38 MeV) for the lambda(1405) in the K- p --> pi0pi0sigma0 reaction.
- The reaction mechanism is dominated by pi0 emission preceding K- p interaction.
- Theoretical analysis supports a two-pole structure for the lambda(1405), with distinct contributions from different energy poles.
Conclusions:
- The K- p --> pi0pi0sigma0 reaction data and theoretical analysis provide strong evidence for the two-pole structure of the lambda(1405) resonance.
- The findings highlight the importance of the higher-energy, narrower pole in the K- p interaction.
- This contrasts with the pi- p --> K0pisigma reaction, which emphasizes a lower-energy, broader pole, further substantiating the two-pole hypothesis.