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]

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...

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Published in:	Physical review. D, Particles and fields Vol. 48:9
Main Authors:	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.
Format:	Journal Article
Language:	English
Published:	United States 01-11-1993
Subjects:	662310 - Weak & Electromagnetic Interactions of Leptons- (1992-) 662420 - Properties of Mesons & Meson Resonances- (1992-) 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 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS PIONS PSEUDOSCALAR MESONS QUARK MODEL RESONANCE
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Summary:	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.
Bibliography:	FG03-91ER40674; AS03-76ER70285; FG03-91ER40662; AT03-87ER40327
ISSN:	0556-2821 1089-4918
DOI:	10.1103/PhysRevD.48.3976