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HK: Fachverband Physik der Hadronen und Kerne

HK 3: Hadron Structure and Spectroscopy II

HK 3.1: Gruppenbericht

Montag, 16. März 2026, 16:15–16:45, PHIL A 401

Light-Meson Spectroscopy at COMPASS — •Stefan Wallner for the COMPASS collaboration — Max Planck Institute for Physics, Garching, Germany

We studied the excitation spectrum of non-strange and strange light mesons with unparalleled precision using the world’s largest sample of diffractive scattering of 190 GeV/c negative pions and kaons recorded at the COMPASS experiment at CERN. We performed partial-wave analyses of data on various final states to identify the produced light-meson resonances and to measure their properties, including spin, parity, mass, and width.

We report on recent results for the ωπ⁻π⁰, η π⁻π⁻π⁺, and K_S⁰ K⁻ final states, which map out a wide range of the non-strange light-meson spectrum. We present measurements of excited a_J and π_J states at high masses, a partly unexplored regime. We also discuss the exotic π₁(1600), the lightest hybrid meson, which we found in various decay channels in these final states. Finally, we present the most comprehensive measurement to date of the strange-meson spectrum in the K⁻π⁻π⁺ final state. There, we found the first candidate for an exotic strange meson with J^P=0⁻.

Keywords: COMPASS; meson spectroscopy; partial-wave analysis (PWA); exotic mesons