Exotic Meson Production in the $f_{1}(1285)π^{-}$ System observed in the Reaction $π^{-} p \to ηπ^{+}π^{-}π^{-} p$ at 18 GeV/c

J. Kuhn

doi:10.1016/j.physletb.2004.05.032

paper

Exotic Meson Production in the $f_{1} (1285) π^{-}$ System observed in the Reaction $π^{-} p \to η π^{+} π^{-} π^{-} p$ at 18 GeV/c

arXiv:hep-ex/0401004 · doi:10.1016/j.physletb.2004.05.032

Abstract

This letter reports results from the partial wave analysis of the $π^{-} π^{-} π^{+} η$ final state in $π^{-} p$ collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin, parity and charge conjugation, $J^{P C} = 1^{-+}$ in the decay channel $f_{1} (1285) π^{-}$ . The mass $M = 1709 \pm 24 \pm 41$ MeV/c^2 and width $Γ = 403 \pm 80 \pm 115$ MeV/c^2 of the first state are consistent with the parameters of the previously observed $π_{1} (1600)$ . The second resonance with mass $M = 2001 \pm 30 \pm 92$ MeV/c^2 and width $Γ = 333 \pm 52 \pm 49$ MeV/c^2 agrees very well with predictions from theoretical models. In addition, the presence of $π_{2} (1900)$ is confirmed with mass $M = 2003 \pm 88 \pm 148$ MeV/c^2 and width $Γ = 306 \pm 132 \pm 121$ MeV/c^2 and a new state, $a_{1} (2096)$ , is observed with mass $M = 2096 \pm 17 \pm 121$ MeV/c^2 and width $Γ = 451 \pm 41 \pm 81$ MeV/c^2. The decay properties of these last two states are consistent with flux tube model predictions for hybrid mesons with non-exotic quantum numbers.

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I = 0 C = +1 mesons from 1920 to 2410 MeV

Exotic Meson Production in the f1​(1285)π− System observed in the Reaction π−p→ηπ+π−π−p at 18 GeV/c

Abstract

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Exotic Meson Production in the $f_{1} (1285) π^{-}$ System observed in the Reaction $π^{-} p \to η π^{+} π^{-} π^{-} p$ at 18 GeV/c