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Title: Evidence for two {lambda}(1405) resonance states

Abstract

The K-p {yields} {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. We use these data in combination with those of the {pi}-p {yields} K0{pi}{sigma} reaction and elements of chiral unitary theory to prove that there are two {lambda}(1405) states instead of one as so far assumed.

Authors:
;  [1];  [2];  [3]
  1. Departamento de Fisica Teorica, Institutos de Investigacion de Paterna -- Universidad de Valencia-CSIC, Apdo. correos 22085, 46071, Valencia (Spain)
  2. (Spain)
  3. Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain)
Publication Date:
OSTI Identifier:
20798078
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 814; Journal Issue: 1; Conference: 11. international conference on hadron spectroscopy, Rio de Janeiro (Brazil), 21-26 Aug 2005; Other Information: DOI: 10.1063/1.2176491; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CHIRALITY; DISTRIBUTION; ENERGY LEVELS; KAON-PROTON INTERACTIONS; LAMBDA-1405 BARYONS; MEV RANGE; PARTICLE PRODUCTION; PARTICLE WIDTHS; PIONS; RESONANCE PARTICLES; SIGMA BARYONS

Citation Formats

Oset, E., Magas, V. K., IFIC, Centro Mixto, Institutos de Investigacion de Paterna -- Universidad de Valencia-CSIC, Apdo. correos 22085, 46071, Valencia, and Ramos, A.. Evidence for two {lambda}(1405) resonance states. United States: N. p., 2006. Web. doi:10.1063/1.2176491.
Oset, E., Magas, V. K., IFIC, Centro Mixto, Institutos de Investigacion de Paterna -- Universidad de Valencia-CSIC, Apdo. correos 22085, 46071, Valencia, & Ramos, A.. Evidence for two {lambda}(1405) resonance states. United States. doi:10.1063/1.2176491.
Oset, E., Magas, V. K., IFIC, Centro Mixto, Institutos de Investigacion de Paterna -- Universidad de Valencia-CSIC, Apdo. correos 22085, 46071, Valencia, and Ramos, A.. Sat . "Evidence for two {lambda}(1405) resonance states". United States. doi:10.1063/1.2176491.
@article{osti_20798078,
title = {Evidence for two {lambda}(1405) resonance states},
author = {Oset, E. and Magas, V. K. and IFIC, Centro Mixto, Institutos de Investigacion de Paterna -- Universidad de Valencia-CSIC, Apdo. correos 22085, 46071, Valencia and Ramos, A.},
abstractNote = {The K-p {yields} {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. We use these data in combination with those of the {pi}-p {yields} K0{pi}{sigma} reaction and elements of chiral unitary theory to prove that there are two {lambda}(1405) states instead of one as so far assumed.},
doi = {10.1063/1.2176491},
journal = {AIP Conference Proceedings},
number = 1,
volume = 814,
place = {United States},
year = {Sat Feb 11 00:00:00 EST 2006},
month = {Sat Feb 11 00:00:00 EST 2006}
}
  • The K{sup -}p{yields}{pi}{sup 0}{pi}{sup 0}{sigma}{sup 0} reaction is studied within a chiral unitary model. The distribution of {pi}{sup 0}{sigma}{sup 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}{sup 0} prior to the K{sup -}p interaction leading to the {lambda}(1405). This ensures the coupling of the {lambda}(1405) to the K{sup -}p channel, thus maximizing the contribution of the second state found in chiral unitary theories, which is narrow and of highermore » energy than the nominal {lambda}(1405). This is unlike the {pi}{sup -}p{yields}K{sup 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, provide firm evidence of the two-pole structure of the {lambda}(1405)« less
  • We use recent data on the K-p {yields} {pi}0{pi}0{sigma}0 reaction with the {pi}0{sigma}0 mass distribution of forming the {lambda}(1405) with a peak at 1420 MeV and a relatively narrow width of {gamma} = 38 MeV, together with those of the {pi}-p {yields} K0{pi}{sigma} reaction to show that there are two {lambda}(1405) states instead of one as so far assumed.
  • In this paper we develop a formalism to evaluate wave functions in momentum and coordinate space for the resonant states dynamically generated in a unitary coupled channel approach. The on-shell approach for the scattering matrix, commonly used, is also obtained in quantum mechanics with a separable potential, which allows one to write wave functions in a trivial way. We develop useful relationships among the couplings of the dynamically generated resonances to the different channels and the wave functions at the origin. The formalism provides an intuitive picture of the resonances in the coupled channel approach, as bound states of onemore » bound channel, which decays into open ones. It also provides an insight and practical rules for evaluating couplings of the resonances to external sources and how to deal with final state interaction in production processes. As an application of the formalism we evaluate the wave functions of the two {Lambda}(1405) states in the {pi}{Sigma}, KN, and other coupled channels. It also offers a practical way to study three-body systems when two of them cluster into a resonance.« less