2025/11/06 by Beygi, Alireza, Klevansky, S. P., Lemmer, R. H.
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2511.04392
We calculate the binding energies of the hypothetical mesonic atom, K+ K- (kaonium), using the K+ K- → K+ K- elastic scattering amplitude. Our findings are in line with previously reported results, which involve solving an eigenvalue equation of the Kudryavtsev-Popov type. Using chiral perturbation theory, we show that kaonium manifests itself as a sharp resonance around 992 MeV accompanying f0 (980) or a0 (980) in cross-sections for processes γγ→ π0 π0 or γγ→ π0 η. The latter process is particularly striking: the peak at the kaonium resonance energy is highly pronounced, with the ratio of the cross-sections σ(γγ→ π0 η) / σ(γγ→ π0 π0) ≈ 9. Due to the short lifetime of kaonium (∼ 10-18 s) and its small decay width (∼ 0.4 keV), direct detection of this exotic atom poses a significant challenge and requires high experimental resolution. However, we show that once the formation of kaonium is considered in the cross-section, a better fit to the available experimental data is obtained.