Search for the $U$ boson in the process $e^+ e^- \to U \gamma$, $U \to e^+ e^-$ with the KLOE detector

TL;DR

This paper reports a search for the dark photon $U$ in electron-positron collisions using the KLOE detector, aiming to identify a resonance that would indicate its existence, but finds no evidence and sets upper limits.

Contribution

The study introduces a novel search strategy for the dark photon $U$ in $e^+ e^- o U o e^+ e^-$ processes using the KLOE detector data, providing new constraints on dark sector interactions.

Findings

No evidence for the $U$ boson was observed.

A preliminary upper limit on the kinetic mixing parameter was established.

The results constrain models of dark sector mediators.

Abstract

Dark Matter and Dark Energy are two of the most fundamental open questions in physics today. The existence of a light dark-force mediator has been hypothesized as a possible explanation for several unexplained physical phenomena. A new search for this mediator, the dark photon $U$, is underway using data collected with the KLOE detector at DA$\Phi$NE. We describe the strategy we will use in our search for a resonant peak in the electron-positron invariant mass spectrum from the process $e^+e^- \to U \gamma$ with $U \to e^+e^-$. So far we found no evidence for the process and set a preliminary upper limit on the level of mixing between the secluded dark sector and the standard model.