Observation of a New Narrow Axial-Vector Meson a1(1420)

The COMPASS Collaboration at CERN has measured diffractive dissociation of 190 GeV/c pions into the π(-)π(-)π(+) final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of 3π mass and four-momentum transfer using the isobar model and the so far largest PW...

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Veröffentlicht in:	Physical review letters 2015-08, Vol.115 (8), p.082001-082001
Hauptverfasser:	Adolph, C, Akhunzyanov, R, Alexeev, M G, Alexeev, G D, Amoroso, A, Andrieux, V, Anosov, V, Austregesilo, A, Azevedo, C, Badełek, B, Balestra, F, Barth, J, Beck, R, Bedfer, Y, Bernhard, J, Bicker, K, Bielert, E R, Birsa, R, Bisplinghoff, J, Bodlak, M, Boer, M, Bordalo, P, Bradamante, F, Braun, C, Bressan, A, Büchele, M, Burtin, E, Chang, W-C, Chiosso, M, Choi, I, Chung, S U, Cicuttin, A, Crespo, M L, Curiel, Q, Dalla Torre, S, Dasgupta, S S, Dasgupta, S, Denisov, O Yu, Dhara, L, Donskov, S V, Doshita, N, Dünnweber, W, Duic, V, Dziewiecki, M, Efremov, A, Eversheim, P D, Eyrich, W, Faessler, M, Ferrero, A, Finger, M, Fischer, H, Franco, C, du Fresne von Hohenesche, N, Friedrich, J M, Frolov, V, Gautheron, F, Gavrichtchouk, O P, Gerassimov, S, Gnesi, I, Gorzellik, M, Grabmüller, S, Grasso, A, Grosse-Perdekamp, M, Grube, B, Grussenmeyer, T, Guskov, A, Haas, F, Hahne, D, von Harrach, D, Hashimoto, R, Heinsius, F H, Herrmann, F, Hinterberger, F, Horikawa, N, d'Hose, N, Hsieh, C-Yu, Huber, S, Ishimoto, S, Ivanov, A, Ivanshin, Yu, Iwata, T, Jahn, R, Jary, V, Jörg, P, Joosten, R, Kabuß, E, Ketzer, B, Khaustov, G V, Khokhlov, Yu A, Kisselev, Yu, Klein, F, Klimaszewski, K, Koivuniemi, J H, Kolosov, V N, Kondo, K, Königsmann, K, Konorov, I, Konstantinov, V F, Kotzinian, A M
Format:	Artikel
Sprache:	eng
Schlagworte:	Bins CERN Channels Cooperation Decay Diffraction Isobars Mesons
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Zusammenfassung:	The COMPASS Collaboration at CERN has measured diffractive dissociation of 190 GeV/c pions into the π(-)π(-)π(+) final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of 3π mass and four-momentum transfer using the isobar model and the so far largest PWA model consisting of 88 waves. A narrow peak is observed in the f0(980)π channel with spin, parity and C-parity quantum numbers J(PC)=1(++). We present a resonance-model study of a subset of the spin-density matrix selecting 3π states with J(PC)=2(++) and 4(++) decaying into ρ(770)π and with J(PC)=1(++) decaying into f0(980)π. We identify a new a1 meson with mass (1414(-13)(+15)) MeV/c2 and width (153(-23)(+8)) MeV/c2. Within the final states investigated in our analysis, we observe the new a1(1420) decaying only into f0(980)π, suggesting its exotic nature.
ISSN:	0031-9007 1079-7114
DOI:	10.1103/PhysRevLett.115.082001