Measurement of eta meson decays into lepton-antilepton pairs
CELSIUS/WASA Collaboration: M. Ber{\l}owski, Chr. Bargholtz, M., Bashkanov, D. Bogoslawsky, A. Bondar, H. Cal\'en, F. Cappellaro, H. Clement,, L. Demir\"ors, C. Ekstr\"om, K. Fransson, L. Ger\'en, L. Gustafsson, B., H\"oistad, G. Ivanov, M. Jacewicz, E. Jiganov, T. Johansson
TL;DR
This study searches for rare eta meson decays into lepton pairs, setting new upper limits on their branching ratios and measuring specific decay modes using the WASA detector at CELSIUS.
Contribution
It provides the first experimental upper limits on eta decays into lepton pairs and measures the eta->e+e-gamma decay branching ratio.
Findings
Upper limit for eta->e+e-e+e- decay is 9.7E-5
Measured eta->e+e-gamma branching ratio as (7.8+/-0.5+/-0.8)E-3
Upper limit for eta->e+e- decay is 2.7E-5
Abstract
A search for rare lepton decays of the eta meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay eta->e+e-e+e- events are reported with a background of 1.3+/-0.2 events. This allows to set an upper limit to the branching ratio of 9.7E-5 (90% CL). The branching ratio for the decay eta->e+e-gamma is determined to (7.8+/-0.5 stat+/-0.8 syst)E-3. An upper limit (90% CL) for the branching ratio for the eta->e+e- decay is 2.7E-5 and a limit for the sum of the eta->mu+mu-mu+mu- and eta->pi+pi-mu+mu- decays is 3.6E-4.
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.