Observation of a J(PC)=1-+ exotic resonance in diffractive dissociation of 190   GeV/c π- into π- π- π

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum trans...

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Veröffentlicht in:Physical review letters 2010-06, Vol.104 (24), p.241803-241803
Hauptverfasser: Alekseev, M G, Alexakhin, V Yu, Alexandrov, Yu, Alexeev, G D, Amoroso, A, Austregesilo, A, Badełek, B, Balestra, F, Ball, J, Barth, J, Baum, G, Bedfer, Y, Bernhard, J, Bertini, R, Bettinelli, M, Birsa, R, Bisplinghoff, J, Bordalo, P, Bradamante, F, Bravar, A, Bressan, A, Brona, G, Burtin, E, Bussa, M P, Chapiro, A, Chiosso, M, Chung, S U, Cicuttin, A, Colantoni, M, Crespo, M L, Dalla Torre, S, Dafni, T, Das, S, Dasgupta, S S, Denisov, O Yu, Dhara, L, Diaz, V, Dinkelbach, A M, Donskov, S V, Doshita, N, Duic, V, Dünnweber, W, Efremov, A, El Alaoui, A, Eversheim, P D, Eyrich, W, Faessler, M, Ferrero, A, Finger, M, Finger, Jr, M, Fischer, H, Franco, C, Friedrich, J M, Garfagnini, R, Gautheron, F, Gavrichtchouk, O P, Gazda, R, Gerassimov, S, Geyer, R, Giorgi, M, Gobbo, B, Goertz, S, Grabmüller, S, Grajek, O A, Grasso, A, Grube, B, Gushterski, R, Guskov, A, Haas, F, von Harrach, D, Hasegawa, T, Heckmann, J, Heinsius, F H, Hermann, R, Herrmann, F, Hess, C, Hinterberger, F, Horikawa, N, Höppner, Ch, d'Hose, N, Ilgner, C, Ishimoto, S, Ivanov, O, Ivanshin, Yu, Iwata, T, Jahn, R, Jasinski, P, Jegou, G, Joosten, R, Kabuss, E, Kang, D, Ketzer, B, Khaustov, G V, Khokhlov, Yu A, Kisselev, Yu, Klein, F, Klimaszewski, K, Koblitz, S, Koivuniemi, J H, Kolosov, V N
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Sprache:eng
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Zusammenfassung:The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1  GeV2/c2. The well-known resonances a1(1260), a2(1320), and π2(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC)=1-+ at 1.66  GeV/c2 decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC)=2-+ and 1++ waves. From a mass-dependent fit a resonance mass of (1660±10(-64)(+0))  MeV/c2 and a width of (269±21(-64)(+42))  MeV/c2 are deduced, with an intensity of (1.7±0.2)% of the total intensity.
ISSN:1079-7114
DOI:10.1103/PhysRevLett.104.241803