Evidence for spin-one resonance production in the reaction γγ*→π+π-π0π0

D. A. Bauer, R. Belcinski, R. C. Berg, H. H. Bingham, C. D. Buchanan, D. O. Caldwell, S. B. Chun, A. R. Clark, O. I. Dahl, M. Daoudi, J. J. Eastman, A. M. Eisner, K. H. Fairfield, G. Godfrey, G. S. Greenbaum, J. M. Hauptman, W. Hofmann, R. L. Holtzapple, S. Khacheryan, K. T. KnöpfleR. R. Kofler, D. J. Lambert, J. G. Layter, W. T. Lin, S. C. Loken, A. Lu, G. R. Lynch, J. E. Lys, R. J. Madaras, G. E. Masek, E. S. Miller, N. A. Nicol, D. R. Nygren, J. Y. Oyang, H. P. Paar, A. P.T. Palounek, D. E. Pellett, M. T. Ronan, R. R. Ross, G. Shapiro, B. C. Shen, R. W. Stephens, M. L. Stevenson, M. G. Strauss, M. K. Sullivan, W. Vernon, E. M. Wang, Y. X. Wang, W. A. Wenzel, H. Yamamoto, S. J. Yellin, G. P. Yost, G. Zapalac, C. Zeitlin

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9 Scopus citations

Abstract

Using data from the TPC/Two-Gamma experiment at the SLAC e+e- storage ring PEP, a C=+1 resonance has been observed in the π+π-π0γ final state resulting from the fusion of one nearly real and one quite virtual photon. The actual decay channel is probably π+π-π0π0, where one final-state photon is not detected, and the mass of the fully reconstructed state would be approximately 1525 MeV. A four-pion decay mode in turn implies that the resonance has even isospin. The nonobservation of this R(1525) when both initial-state photons are nearly real suggests a spin-1 assignment. Since the large measured value of the product of the branching ratio into π+π-π0π0 and the γγ coupling makes it unlikely that this state is the mostly s̄s f1(1510), its interpretation may lie outside of conventional meson spectroscopy. There is a second, less-significant enhancement observed in the same reaction at a four-pion mass centered around 2020 MeV.

Original languageEnglish
Pages (from-to)3976-3986
Number of pages11
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume48
Issue number9
DOIs
StatePublished - 1993

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