Study of the process $$e^+e^- \rightarrow \eta \eta \gamma $$ in the energy range $$\sqrt{s} = \text{1.17--2.00 }$$ GeV with the SND detector

• Published in: The European physical journal. C, Particles and fields Vol. 82; no. 2
• Main Authors: Achasov, M. N., Barnyakov, A. Yu, Beloborodov, K. I., Berdyugin, A. V., Berkaev, D. E., Bogdanchikov, A. G., Botov, A. A., Dimova, T. V., Druzhinin, V. P., Kirpotin, A. N., Kardapoltsev, L. V., Kasaev, A. S., Kharlamov, A. G., Koop, I. A., Korol, A. A., Kovrizhin, D. P., Kupich, A. S., Martin, K. A., Melnikova, N. A., Muchnoy, N. Yu, Obrazovsky, A. E., Pakhtusova, E. V., Pugachev, K. V., Rabusov, D. V., Rogovsky, Yu. A., Senchenko, A. I., Serednyakov, S. I., Shatilov, D. N., Shatunov, Yu. M., Shtol, D. A., Shwartz, D. B., Silagadze, Z. K., Surin, I. K., Timoshenko, M. V., Usov, Yu. V., Zhabin, V. N., Zhulanov, V. V.
• Format: Journal Article
• Language: English
• Published: 01-02-2022
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-022-10102-9

Abstract
The process
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb
$$^{-1}$$
-
1
collected by the SND detector at the VEPP-2000
$$e^+e^-$$
e
+
e
-
collider. The
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
$$\phi \eta $$
ϕ
η
intermediate state. Our result on the
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
cross section is consistent with the
$$e^+e^-\rightarrow \phi \eta $$
e
+
e
-
→
ϕ
η
measurement in the
$$\phi \rightarrow K^+ K^-$$
ϕ
→
K
+
K
-
mode. The search for radiative processes contributing to the
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
cross section is performed, and no significant signal is observed.