Observation of a New Narrow Axial-Vector Meson a1(1420)
Affiliations
- 1 Universität Erlangen-Nürnberg, Physikalisches Institut, 91054 Erlangen, Germany.
- 2 Joint Institute for Nuclear Research, 141980 Dubna, Moscow region, Russia.
- 3 University of Turin, Department of Physics, 10125 Turin, Italy.
- 4 Torino Section of INFN, 10125 Turin, Italy.
- 5 CEA IRFU/SPhN Saclay, 91191 Gif-sur-Yvette, France.
- 6 CERN, 1211 Geneva 23, Switzerland.
- 7 Technische Universität München, Physik Department, 85748 Garching, Germany.
- 8 University of Aveiro, Department of Physics, 3810-193 Aveiro, Portugal.
- 9 University of Warsaw, Faculty of Physics, 02-093 Warsaw, Poland.
- 10 Universität Bonn, Physikalisches Institut, 53115 Bonn, Germany.
- 11 Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, 53115 Bonn, Germany.
- 12 Universität Mainz, Institut für Kernphysik, 55099 Mainz, Germany.
- 13 Trieste Section of INFN, 34127 Trieste, Italy.
- 14 Charles University in Prague, Faculty of Mathematics and Physics, 18000 Prague, Czech Republic.
- 15 LIP, 1000-149 Lisbon, Portugal.
- 16 University of Trieste, Department of Physics, 34127 Trieste, Italy.
- 17 Universität Freiburg, Physikalisches Institut, 79104 Freiburg, Germany.
- 18 Academia Sinica, Institute of Physics, Taipei 11529, Taiwan.
- 19 University of Illinois at Urbana-Champaign, Department of Physics, Urbana, Illinois 61801-3080, USA.
- 20 Abdus Salam ICTP, 34151 Trieste, Italy.
- 21 Matrivani Institute of Experimental Research & Education, Calcutta-700 030, India.
- 22 State Scientific Center Institute for High Energy Physics of National Research Center 'Kurchatov Institute', 142281 Protvino, Russia.
- 23 Yamagata University, Yamagata 992-8510 Japan.
- 24 University of Eastern Piedmont, 15100 Alessandria, Italy.
- 25 Universität Bochum, Institut für Experimentalphysik, 44780 Bochum, Germany.
- 26 Institute of Scientific Instruments, AS CR, 61264 Brno, Czech Republic.
- 27 Technical University in Liberec, 46117 Liberec, Czech Republic.
- 28 University of Miyazaki, Miyazaki 889-2192, Japan.
- 29 Lebedev Physical Institute, 119991 Moscow, Russia.
- 30 Nagoya University, 464 Nagoya, Japan.
- 31 Czech Technical University in Prague, 16636 Prague, Czech Republic.
- 32 Tel Aviv University, School of Physics and Astronomy, 69978 Tel Aviv, Israel.
- 33 National Centre for Nuclear Research, 00-681 Warsaw, Poland.
- 34 Warsaw University of Technology, Institute of Radioelectronics, 00-665 Warsaw, Poland.
- PMID: 26340182
- DOI: 10.1103/PhysRevLett.115.082001
Observation of a New Narrow Axial-Vector Meson a1(1420)
Authors
Affiliations
- 1 Universität Erlangen-Nürnberg, Physikalisches Institut, 91054 Erlangen, Germany.
- 2 Joint Institute for Nuclear Research, 141980 Dubna, Moscow region, Russia.
- 3 University of Turin, Department of Physics, 10125 Turin, Italy.
- 4 Torino Section of INFN, 10125 Turin, Italy.
- 5 CEA IRFU/SPhN Saclay, 91191 Gif-sur-Yvette, France.
- 6 CERN, 1211 Geneva 23, Switzerland.
- 7 Technische Universität München, Physik Department, 85748 Garching, Germany.
- 8 University of Aveiro, Department of Physics, 3810-193 Aveiro, Portugal.
- 9 University of Warsaw, Faculty of Physics, 02-093 Warsaw, Poland.
- 10 Universität Bonn, Physikalisches Institut, 53115 Bonn, Germany.
- 11 Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, 53115 Bonn, Germany.
- 12 Universität Mainz, Institut für Kernphysik, 55099 Mainz, Germany.
- 13 Trieste Section of INFN, 34127 Trieste, Italy.
- 14 Charles University in Prague, Faculty of Mathematics and Physics, 18000 Prague, Czech Republic.
- 15 LIP, 1000-149 Lisbon, Portugal.
- 16 University of Trieste, Department of Physics, 34127 Trieste, Italy.
- 17 Universität Freiburg, Physikalisches Institut, 79104 Freiburg, Germany.
- 18 Academia Sinica, Institute of Physics, Taipei 11529, Taiwan.
- 19 University of Illinois at Urbana-Champaign, Department of Physics, Urbana, Illinois 61801-3080, USA.
- 20 Abdus Salam ICTP, 34151 Trieste, Italy.
- 21 Matrivani Institute of Experimental Research & Education, Calcutta-700 030, India.
- 22 State Scientific Center Institute for High Energy Physics of National Research Center 'Kurchatov Institute', 142281 Protvino, Russia.
- 23 Yamagata University, Yamagata 992-8510 Japan.
- 24 University of Eastern Piedmont, 15100 Alessandria, Italy.
- 25 Universität Bochum, Institut für Experimentalphysik, 44780 Bochum, Germany.
- 26 Institute of Scientific Instruments, AS CR, 61264 Brno, Czech Republic.
- 27 Technical University in Liberec, 46117 Liberec, Czech Republic.
- 28 University of Miyazaki, Miyazaki 889-2192, Japan.
- 29 Lebedev Physical Institute, 119991 Moscow, Russia.
- 30 Nagoya University, 464 Nagoya, Japan.
- 31 Czech Technical University in Prague, 16636 Prague, Czech Republic.
- 32 Tel Aviv University, School of Physics and Astronomy, 69978 Tel Aviv, Israel.
- 33 National Centre for Nuclear Research, 00-681 Warsaw, Poland.
- 34 Warsaw University of Technology, Institute of Radioelectronics, 00-665 Warsaw, Poland.
- PMID: 26340182
- DOI: 10.1103/PhysRevLett.115.082001
Abstract
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.
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