Precision spectroscopy with COMPASS and the observation of a new iso-vector resonance
1 Physik Department E18, Technische Universität München, James Franck Str., 85748 Garching, Germany
2 Excellencecluster “Universe”, Boltzmannstr. 2, 85748 Garching, Germany
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Published online: 9 June 2014
We report on the results of a novel partial-wave analysis based on 50 ⋅ 106 events from the reaction π− + p → π−π−π+ + precoil at 190 GeV/c incoming beam momentum using the COMPASS spectrometer. A separated analysis in bins of m3π and four-momentum transfer t′ reveals the interference of resonant and non-resonant particle production and allows their spectral separation. Besides well known resonances we observe a new iso-vector meson a1(1420) at a mass of 1420 MeV/c2 in the f0(980)π final state only, the origin of which is unclear. We have also examined the structure of the 0++ππ-isobar in the JPC = 0−+, 1++, 2−+ three pion waves. This clearly reveals the various 0++ππ-isobar components and its correlation to the decay of light mesons.
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