2024/06/04 by Shi-Dong Liu, Liu, Shi-Dong, F. Wang +9 · 1 citation
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear physics research studies #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2406.01874
openalex publication_date 2024/06/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigated the pionic transitions between the X2 [spin-2 partner of the X(3872)] and χc1,2 using a nonrelativistic effective field theory. The X2 is assumed to be a bound state of the D* and D^* mesons and to decay through several kinds of loops, including the bubble, triangle and box loops. Within the present model, the widths for the single-pion decays X2→π0χcJ are predicted to be about 3--30 keV. For the dipion decays, the widths are a few keVs. These widths yield a branching fraction of 10-3--10-2. The ratio Rc0=Γ(X2→π+π-χcJ)/Γ(X2→π0π0χcJ) ≃ 1.6, which is a bit smaller than the expected value of 2, and R21=Γ(X2→ππχc2)/Γ(X2→ππχc1) ≃ 0.85. These ratios are nearly independent of the X2 mass and the coupling constants, which might be a good quantity for the experiments. Moreover, the invariant mass spectra of the π0χcJ final state for the dipion processes are presented, showing a cusp structure at the D D^* threshold enhanced and narrowed by the nearby triangle singularity.