Measurement of η → π0γγ branching fraction with the KLOE detector

Journal of High Energy Physics 2026 Open access

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Authors: Danilo Babusci, Paolo Beltrame, Marcin Berlowski, C. Bloise, F. Bossi, P. Branchini, Bo Cao, Filippo Ceradini, P. Ciambrone, L. Cotrozzi, F. Curciarello, E. Czerwiński
+41 more G. D’Agostini, Riccardo d'Amico, Emiliano Dané, V. De Leo, Erika De Lucia, A. De Santis, P. De Simone, A. Di Domenico, Eleonora Diociaiuti, D. Domenici, A. D'Uffizi, G. Fantini, Salvatore Fiore, A. Gajos, S. Gamrat, P. Gauzzi, Simona Giovannella, E. Graziani, F. Ignatov, X. Kang, A. Kupsc, G. Mandaglio, M. Martini, S. Miscetti, P. Moskal, A. Passeri, V. Patera, E. Perez del Rio, Lorenzo Punzi, F. Sborzacchi, M. Schioppa, A. Selce, Michał Silarski, F. Sirghi, E. P. Solodov, T. Teubner, G. Venanzoni, N. Vestergaard, W. Wiślicki, M. Wolke, E. Zaid
DOI: 10.1007/jhep01(2026)091
Cited by: 1
References: 14

Abstract

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 $$\mathcal{B}(\eta \to {\pi }^{0}\gamma \gamma )$$ 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.

Fields of Study & Subjects

Particle physics theoretical and experimental studies Quantum Chromodynamics and Particle Interactions High-Energy Particle Collisions Research

Publication details

Journal / source
Journal of High Energy Physics
Publisher
Springer Science and Business Media LLC
Volume
2026
Issue
1
Publication date
15 January 2026
Language
EN