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arXiv · 2310.09148

Non-strange light-meson spectroscopy at COMPASS

Philipp Haas
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Abstract

Lattice-QCD predicts the exotic meson $\pi_1(1600)$ to dominantly decay to $b_1\pi$. The $b_1\pi$ decay channel is accessible via the $\omega\pi^{-}\pi^{0}$ final state. COMPASS recorded the so far largest data set of this final state. A partial-wave analysis allows to determine the resonant content in this final state including possible contributions from $\pi_1(1600)$. Decomposing the measured intensity into amplitudes of partial waves gives a first qualitative insight into contributing intermediate states. We observe signals in agreement with well-established states like the $\pi(1800)$ and $a_4(1970)$. Smaller resonance-like signals are visible in the $J^{PC}$ sectors $3^{++}$ and $6^{++}$, where possible states were claimed but none are established. For $J^{PC}=1^{-+}$ a signal at $1.65\,\mathrm{GeV/}c^{2}$ in $b_1(1235)\pi$ partial waves is consistent with the expected $\pi_1(1600)$.

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Philipp Haas. 2023-10-13. Non-strange light-meson spectroscopy at COMPASS. https://arxiv.org/abs/2310.09148

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