Study of the process in the energy range GeV with the SND detector - SND Collaboration

M. N. Achasov; A. Yu. Barnyakov; A. A. Baykov; K. I. Beloborodov; A. V. Berdyugin; D. E. Berkaev; A. G. Bogdanchikov; A. A. Botov; T. V. Dimova; V. P. Druzhinin; V. B. Golubev; A. N. Kirpotin; L. V. Kardapoltsev; A. S. Kasaev; A. G. Kharlamov; I. A. Koop; A. A. Korol; D. P. Kovrizhin; A. S. Kupich; K. A. Martin; N. A. Melnikova; N. Yu. Muchnoy; A. E. Obrazovsky; E. V. Pakhtusova; K. V. Pugachev; D. V. Rabusov; Yu. A. Rogovsky; Y. S. Savchenko; A. I. Senchenko; S. I. Serednyakov; D. N. Shatilov; Yu. M. Shatunov; D. A. Shtol; D. B. Shwartz; Z. K. Silagadze; I. K. Surin; M. V. Timoshenko; Yu. V. Usov; V. N. Zhabin; V. V. Zhulanov

doi:10.1140/epjc/s10052-020-08556-w

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2020) 80: 1008
https://doi.org/10.1140/epjc/s10052-020-08556-w

Regular Article – Experimental Physics

Study of the process $e^{+} e^{-} \to η π^{0} γ$ $e^+e^- \rightarrow \eta \pi ^0\gamma$ in the energy range $\sqrt{s} = 1.05 - 2.00$ $\sqrt{s} = {1.05-2.00}$ GeV with the SND detector

SND Collaboration

M. N. Achasov¹^,2, A. Yu. Barnyakov¹^,2, A. A. Baykov¹^,2, K. I. Beloborodov¹^,2, A. V. Berdyugin¹^,2, D. E. Berkaev¹^,2, A. G. Bogdanchikov¹, A. A. Botov¹, T. V. Dimova¹^,2, V. P. Druzhinin¹^,2, V. B. Golubev¹, A. N. Kirpotin¹, L. V. Kardapoltsev¹^,2^p, A. S. Kasaev¹, A. G. Kharlamov¹^,2, I. A. Koop¹^,2, A. A. Korol¹^,2, D. P. Kovrizhin¹, A. S. Kupich¹, K. A. Martin¹, N. A. Melnikova¹, N. Yu. Muchnoy¹^,2, A. E. Obrazovsky¹, E. V. Pakhtusova¹, K. V. Pugachev¹^,2, D. V. Rabusov¹, Yu. A. Rogovsky¹^,2, Y. S. Savchenko¹^,2, A. I. Senchenko¹^,2, S. I. Serednyakov¹^,2, D. N. Shatilov¹, Yu. M. Shatunov¹^,2, D. A. Shtol¹, D. B. Shwartz¹^,2, Z. K. Silagadze¹^,2, I. K. Surin¹, M. V. Timoshenko¹, Yu. V. Usov¹, V. N. Zhabin¹ and V. V. Zhulanov¹^,2

¹ Budker Institute of Nuclear Physics, SB RAS, 630090, Novosibirsk, Russia
² Novosibirsk State University, 630090, Novosibirsk, Russia

^p l.v.kardapoltsev@inp.nsk.su

Received: 11 June 2020
Accepted: 14 October 2020
Published online: 1 November 2020

Abstract

The process $e^{+} e^{-} \to η π^{0} γ$ $e^+e^-\rightarrow \eta \pi ^0\gamma$ is studied in the center-of-mass energy range 1.05–2.00 GeV using data with an integrated luminosity of 94.5 ${pb}^{- 1}$ $\hbox {pb}^{-1}$ collected by the SND detector at the VEPP-2000 $e^{+} e^{-}$ $e^{+}e^{-}$ collider. The $e^{+} e^{-} \to η π^{0} γ$ $e^+e^-\rightarrow \eta \pi ^0\gamma$ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $ω η$ $\omega \eta$ intermediate state. The measured cross section of the subprocess $e^{+} e^{-} \to ω η \to η π^{0} γ$ $e^+e^-\rightarrow \omega \eta \rightarrow \eta \pi ^0\gamma$ is consistent with previous measurements in the $e^{+} e^{-} \to π^{+} π^{-} π^{0} η$ $e^+e^-\rightarrow \pi ^+\pi ^-\pi ^0\eta$ mode. It is found, with a significance of $5.6 σ$ $5.6\sigma$ , that the process $e^{+} e^{-} \to η π^{0} γ$ $e^+e^-\rightarrow \eta \pi ^0\gamma$ is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g. $e^{+} e^{-} \to a_{0} (1450) γ$ $e^+e^-\rightarrow a_{0}(1450)\gamma$ , is measured. It is found to be 15–20 pb in the wide energy range from 1.3 to 1.9 GeV.

© The Author(s) 2020

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