Establish the decay pattern of the a1(1930)

Establish the decay pattern and relative branching fractions of the proposed a1(1930) compact 1++ tetraquark candidate, particularly in the K* K and f0(980) pi final states, through experimental measurements.

Background

The Gaussian sum-rule analysis identifies a heavier hidden-strange 1++ state with mass approximately 1.86 GeV and suggests that it may correspond to the a1(1930) resonance. Based on the hidden-strange us anti-u anti-s component of the interpolating currents, the paper predicts that K* K and f0(980) pi could be important decay channels, with possible contributions from K1 K and rho pi.

The experimentally observed decay pattern of the a1(1930) is not yet settled. Establishing its decay modes and measuring their relative branching fractions would provide a test of the proposed compact tetraquark interpretation and help distinguish it from conventional or molecular descriptions.

References

Experimentally, the $a_{1}(1930)$ has been observed in several production processes, but its decay pattern is not yet fully established.

— QCD sum rule analysis of hidden strange $1^{++}$ tetraquark masses and radial excitations  (2609.04628 - Huang et al., 4 Sep 2026) in Section 6, “Decay Patterns of the Heavier Tetraquark Candidate a1(1930)”