Triangle singularity as the origin of the a1(1420)

Abstract: The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the 1⁡(1420), decaying to 0⁡(980)⁢ . With a mass too close to and a width smaller than the axial-vector ground state 1⁡(1260), it was immediately interpreted as a new light exotic meson, similar to the , , states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the 1⁡(1260) resonance into *⁡(→ ⁡ )⁢
¯ and subsequent rescattering through a triangle singularity into the coupled 0⁡(980)⁢ channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the light-meson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Physical review letters. - 127, 8 (2021) , 082501, ISSN: 1079-7114

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2024
• Creator: Alexeev, Dmitry G. ; Gorzellik, Matthias ; Herrmann, Florian ; Jörg, Philipp ; Mallot, Gerhard Konrad ; Ziembicki, Marcin

Further information

• DOI: 10.1103/physrevlett.127.082501
• URN: urn:nbn:de:bsz:25-freidok-2479845
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:50 PM CET