Journal Article

Measurement of η → π0γγ branching fraction with the KLOE detector

Kupsc, A., De Leo, V., Berlowski, M., Di Domenico, A., Mandaglio, G., Danè, E., Sirghi, F., Venanzoni, G., Gauzzi, P., Ceradini, F., Diociaiuti, E., Moskal, P., Selce, A., Cao, B., Ignatov, F., Beltrame, P., Schioppa, M., Giovannella, S., Miscetti, S., Zaid, E., Martini, M., Branchini, P., De Lucia, E., Silarski, M., D’Uffizi, A., Patera, V., Ciambrone, P., Kang, X., Fantini, G., Bossi, F., Curciarello, F., Babusci, D., Czerwiński, E., Domenici, D., De Santis, A., Fiore, S., Perez del Rio, E., Gajos, A., Graziani, E., Vestergaard, N., Passeri, A., De Simone, P., Wiślicki, W., Bloise, C., D’Agostini, G., Punzi, L., Teubner, T., Gamrat, S., Cotrozzi, L., Sborzacchi, F., D’Amico, R., Solodov, E. P., Wolke, M.

2026

Overview

A bstract We present a measurement of the doubly radiative decay η → π 0 γγ based on a sample of 82 million η mesons produced in the e + e − → ϕ → ηγ process at the Frascati ϕ -factory DAΦNE. From the data analysis, 1246 ± 133 signal events were observed. By normalising the signal to the well-known η → 3 π 0 decay the branching fraction is measured to be (0 . 98 ± 0 . 11 stat ± 0 . 14 syst ) × 10 − 4 . This result agrees with a preliminary KLOE measurement, but is a factor of two smaller than the current world average. Results for d Γ( η → π 0 γγ ) /dM 2 ( γγ ) are also presented and compared with the latest theoretical predictions.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Classical and Quantum Gravitation / Collaboration / Data analysis / Decay / Elementary Particles / Eta-mesons / Nuclear physics / Nuclear research / Physics / Physics and Astronomy / Quantum Field Theories / Quantum Field Theory / Quantum Physics / Quarks / Regular Article - Experimental Physics / Relativity Theory / Sensors / String Theory