Jun 5 – 9, 2023
Genova, Italy
Europe/Rome timezone

Observation of isoscalar 1^(-+) spin-exotic state, η_1 (1855)

Jun 5, 2023, 4:30 PM
DAD - Room 4H (Genova, Italy)

DAD - Room 4H

Genova, Italy

Invited Exotic hadrons and candidates Exotic hadrons and candidates


runqiu ma (Insititute of High Energy Physics, CAS)


Based on a sample of 10 billion J⁄ψ events collected with the BESIII detector, a partial wave analysis of the decay J⁄ψ □(→) γηη' is performed. An isoscalar state with exotic J^PC=1^(-+) quantum numbers, denoted as η_1 (1855), has been observed for the first time with statistical significance larger than 19σ. Its mass is consistent with the predicted mass of 1^(-+) hybrid from Lattice QCD. This is an observation of a new category of hadronic matter, which opens a new direction to complete the picture of spin-exotics.

Primary authors

Beijiang Liu (Institute of High Energy Physics) runqiu ma (Insititute of High Energy Physics, CAS)

Presentation materials

Peer reviewing