$\gamma\gamma$ physics with the KLOE experiment

TL;DR

This paper reports on the study of two-photon processes producing eta and neutral pion pairs at DAΦNE using the KLOE detector, providing preliminary observations and evidence for these rare interactions at energies below the phi resonance.

Contribution

It presents new measurements of gamma-gamma interactions producing eta and pion pairs at DAΦNE, expanding understanding of two-photon physics in this energy regime.

Findings

Observation of gamma-gamma to eta process in two decay channels.

Evidence for gamma-gamma to pi0 pi0 production at low invariant mass.

Data collected with 240 pb^{-1} luminosity at 1 GeV energy.

Abstract

The processes $e^+e^-\to e^+e^-X$, with $X$ being either the $\eta$ meson or $\pi^0\pi^0$, are studied at DA$\Phi$NE, with $e^+e^-$ beams colliding at $\sqrt{s}\simeq1$ GeV, below the $\phi$ resonance peak. The data sample is from an integrated luminosity of 240 pb$^{-1}$, collected by the KLOE experiment without tagging of the outgoing $e^+e^-$. Preliminary results are presented on the observation of the $\gamma\gamma\to\eta$ process, with both $\eta\to\pi^+\pi^-\pi^0$ and $\eta\to\pi^0\pi^0\pi^0$ channels, and the evidence for $\gamma\gamma\to\pi^0\pi^0$ production at low $\pi^0\pi^0$ invariant mass.