Evidence for ϱ1(1270) production in the reaction K-p → π+π-Λ

D. Aston, N. Awaji, T. Bienz, F. Bird, J. D'Amore, W. Dunwoodie, R. Endorf, K. Fujii, H. Hayashii, S. Iwata, W. Johnson, R. Kajikawa, P. Kunz, Y. Kwon, D. Leith, L. Levinson, J. Martinez, T. Matsui, B. Meadows, A. MiyamotoM. Nussbaum, H. Ozaki, C. Pak, B. Ratcliff, P. Rensing, D. Schultz, S. Shapiro, T. Shimomura, P. Sinervo, A. Sugiyama, S. Suzuki, G. Tarnopolsky, T. Tauchi, N. Toge, K. Ukai, A. Waite, S. Williams

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26 Citations (Scopus)


Preliminary results are presented from an analysis of the π+π- system produced in the reaction K-p → π+π-Λ at 11 GeV/c observed with the LASS spectrometer at SLAC. A clear ρ{variant} - ω interference effect is observed, and a fit to the natural parity exchange mass distribution yields a branching fraction estimate of (1.7 ± 0.5) % for the decay ω → π+π-. An amplitude analysis reveals that the bump in the mass distribution in the vicinity of the f{hook}2(1270) actually contains a significant P-wave component. The mass dependence of the corresponding amplitude and phase is well described by a resonant Breit-Wigner line-shape with mass (1266 ± 14) MeV/c2, width (166 ± 35) MeV/c2, and estimated elasticity ∼ 5%. The interpretation of this state as the first radial excitation of the ρ{variant}(770) is discussed.

Original languageEnglish
Pages (from-to)105-110
Number of pages6
JournalNuclear Physics B (Proceedings Supplements)
Issue numberC
Publication statusPublished - 1991 Jun

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Nuclear and High Energy Physics


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