Search for the double Dalitz decays $η/η' \to e^+e^-μ^+μ^-$ and $η' \to μ^+μ^-μ^+μ^-$

{getToc} $title={Table of Contents}

Summary

The BESIII Collaboration searched for the decays η/η′ → e+e− µ+µ− and η′ → µ+µ− µ+µ− using a data sample of (10087±44)×106 J/ψ events. No excess of events over expected background was observed, and upper limits on the branching fractions were set.

Highlights

• The BESIII Collaboration searched for the decays η/η′ → e+e− µ+µ− and η′ → µ+µ− µ+µ−.
• No excess of events over expected background was observed.
• Upper limits on the branching fractions were set at 90% confidence level.
• The upper limit for η → e+e− µ+µ− was improved by two orders of magnitude.
• Theoretical predictions for the branching fractions were summarized.
• The future super τ-charm facility will provide an excellent opportunity to improve the measurements.
• The BESIII detector and Monte Carlo simulation were used in the analysis.

Key Insights

• The search for the decays η/η′ → e+e− µ+µ− and η′ → µ+µ− µ+µ− is important for understanding the transition form factors of the η and η′ mesons, which play a crucial role in the evaluation of the hadronic light-by-light contribution to the muon anomalous magnetic moment.
• The non-observation of these decays and the setting of upper limits on their branching fractions provide valuable constraints on theoretical models, such as the hidden gauge model, the modified vector meson dominance model, and the data-driven approach.
• The improvement of the upper limit for η → e+e− µ+µ− by two orders of magnitude demonstrates the power of the BESIII experiment in searching for rare decays.
• The comparison of the experimental upper limits with theoretical predictions highlights the need for more data to explore the transition form factors and test different theoretical models.
• The future super τ-charm facility will provide an excellent opportunity to improve the measurements of these decays and explore the transition form factors in more detail.
• The analysis demonstrates the importance of the BESIII detector and Monte Carlo simulation in searching for rare decays and understanding the properties of the η and η′ mesons.
• The results of this analysis contribute to our understanding of the strong interaction and the properties of mesons, which is essential for advancing our knowledge of particle physics.

Mindmap

If MindMap doesn't load, go to the Homepage and visit blog again or Switch to Android App (Under Development).

Citation

BESIII Collaboration, Ablikim, M., Achasov, M. N., Adlarson, P., Afedulidis, O., Ai, X. C., Aliberti, R., Amoroso, A., Bai, Y., Bakina, O., Balossino, I., Ban, Y., Bao, H.-R., Batozskaya, V., Begzsuren, K., Berger, N., Berlowski, M., Bertani, M., Bettoni, D., … Zu, J. (2024). Search for the double Dalitz decays $η/η’ \to e^+e^-μ^+μ^-$ and $η’ \to μ^+μ^-μ^+μ^-$ (Version 1). arXiv. https://doi.org/10.48550/ARXIV.2412.19702