Triangle singularity in light meson sector

by Mikhail Mikhasenko (Excellence Cluster ORIGINS)

Monday 4 Apr 2022, 11:15 → 12:00 Europe/Zurich

Hybrid

The talk will discuss one of the prime candidates for exotic hadrons in the light-meson sector, the tetraquark candidate $a_1(1420)$ located in the vicinity of the $K^* \bar{K}$ threshold.
Our recent studies at the COMPASS experiment at SPS at CERN show an evidence for a so-called triangle singularity, a much sought-after effect of the strong interaction.
The analysis suggests that the resonance-like signal, $a_1(1420)$, seen in the $f_0(980)\pi$ spectrum is produced by such a triangle singularity, which causes the particles produced in the collision to change their identities via mutual interaction.
The discovery leads to a recognition of peculiar properties of other exotic near-threshold hadrons such as a production of tertaquarks $T_cc$, and $\chi_{c1}(3872)$ as well as shed a new light to the nature of pentaquarks.

2022-04-04_MM_traingle_singularity_EPFL.pdf