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First observation of the Λ(1405) line shape in electroproduction

Journal Article · · Physical Review. C, Nuclear Physics
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We report the first observation of the line shape of the Λ ( 1405 ) from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of K + Λ ( 1405 ) off the proton was studied by using data from CLAS at Jefferson Lab in the range 1.0 < Q 2 < 3.0 (GeV/ c ) 2 . The analysis utilized the decay channels Σ + π - of the Λ ( 1405 ) and p π 0 of the Σ + . Neither the standard Particle Data Group resonance parameters, nor free parameters fitting to a single Breit-Wigner resonance represent the line shape. In our fits, the line shape corresponds approximately to predictions of a two-pole meson-baryon picture of the Λ ( 1405 ) , with a lower mass pole near 1368 MeV/ c 2 and a higher mass pole near 1423 MeV/ c 2 . Furthermore, with increasing photon virtuality the mass distribution shifts toward the higher mass pole.
Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
DOE Contract Number:
AC02-06CH11357
OSTI ID:
1395170
Journal Information:
Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 4 Vol. 88; ISSN 0556-2813; ISSN PRVCAN
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

References (27)

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