First Observation of the {Lambda}(1405) Line Shape in Electroproduction
- Iowa State U.
- Carnegie Mellon U.
We report the first observation of the line shape of the {Lambda}(1405) from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of K{sup +}{Lambda}(1405) off the proton was studied by using data from CLAS at Jefferson Lab in the range 1.0<Q{sup 2}<3.0 (GeV/c){sup 2}. The analysis utilized the decay channels {Sigma}{sup +}{pi}{sup -} of the {Lambda}(1405) and p{pi}{sup 0} of the {Sigma}{sup +}. 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 {Lambda}(1405), with a lower mass pole near 1368 MeV/c{sup 2} and a higher mass pole near 1423 MeV/c{sup 2}. Furthermore, with increasing photon virtuality the mass distribution shifts toward the higher mass pole.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1096852
- Report Number(s):
- JLAB-PHY-13-1758; DOE/OR/23177-2651; arXiv:1307.4411
- Journal Information:
- Phys. Rev. C, Vol. 88, Issue 04
- Country of Publication:
- United States
- Language:
- English
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