Evidence for spin-one resonance production in the reaction [gamma][gamma][sup *][r arrow][pi][sup +][pi][sup [minus]][pi][sup 0][pi][sup 0]

Journal Article · Mon Nov 01 04:00:00 EST 1993 · Physical Review, D (Particles Fields); (United States)

DOI:https://doi.org/10.1103/PhysRevD.48.3976· OSTI ID:5925405

Bauer, D A; Belcinski, R; Berg, R C; Bingham, H H; Buchanan, C D; Caldwell, D O; Chun, S; Clark, A R; Dahl, O I; Daoudi, M; Eastman, J J; Eisner, A M; Fairfield, K H; Godfrey, G; Greenbaum, G S; Hauptman, J M; Hofmann, W; Holtzapple, R L; Khacheryan, S; Knoepfle, K T ; Kofler, R R; Lambert, D J; Layter, J G; Lin, W T; Loken, S C; Lu, A; Lynch, G R; Lys, J E; Madaras, R J; Masek, G E; Miller, E S; Nicol, N A; Nygren, D R; Oyang, J Y; Paar, H P; Palounek, A P.T.; Pellett, D E; Ronan, M T; Ross, R R; Shapiro, G; Shen, B C; Stephens, R W; Stevenson, M L; Strauss, M G; Sullivan, M K; Vernon, W; Wang, E M; Wang, Y; Wenzel, W A; Yamamoto, H; Yellin, S J; Yost, G P; Zapalac, G; Zeitlin, C ^[1]

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1. University of California, Berkeley, California 94720 (United States) University of California, Davis, California 95616 (United States) University of California Intercampus Institute for Research at Particle Accelerators, Stanford, California 94305 (United

Using data from the TPC/Two-Gamma experiment at the SLAC [ital e][sup +][ital e[minus]] storage ring PEP, a [ital C]=+1 resonance has been observed in the [pi][sup +][pi][sup [minus]][pi][sup 0][gamma] final state resulting from the fusion of one nearly real and one quite virtual photon. The actual decay channel is probably [pi][sup +][pi][sup [minus]][pi][sup 0][pi][sup 0], 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 [ital 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 [pi][sup +][pi][sup [minus]][pi][sup 0][pi][sup 0] and the [gamma][gamma] coupling makes it unlikely that this state is the mostly [ital [bar s]s] [ital f][sub 1](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.

• DOE Contract Number: FG03-91ER40674; AS03-76ER70285; FG03-91ER40662; AT03-87ER40327
• OSTI ID: 5925405
• Journal Information: Physical Review, D (Particles Fields); (United States), Journal Name: Physical Review, D (Particles Fields); (United States) Vol. 48:9; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

662310 -- Weak & Electromagnetic Interactions of Leptons-- (1992-)
662420* -- Properties of Mesons & Meson Resonances-- (1992-)
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BASIC INTERACTIONS
BOSONS
BRANCHING RATIO
COMPOSITE MODELS
COUPLING
ELECTROMAGNETIC INTERACTIONS
ELEMENTARY PARTICLES
HADRONS
INTERACTIONS
MASSLESS PARTICLES
MATHEMATICAL MODELS
MESONS
PARTICLE INTERACTIONS
PARTICLE MODELS
PARTICLE PRODUCTION
PHOTON-PHOTON INTERACTIONS
PHOTONS
PIONS
PSEUDOSCALAR MESONS
QUARK MODEL
RESONANCE