PoS - Proceedings of Science
Volume 457 - Workshop Italiano sulla Fisica  ad Alta Intensità (WIFAI2023) - session Dark sector
Dark sector searches at NA64-$e$
A. Celentano
Full text: pdf
Pre-published on: March 12, 2024
Published on:
The Light Dark Matter (LDM) hypothesis identifies dark matter particles with new sub-GeV ``Hidden Sector'' states, neutral under Standard Model interactions and interfacing with our world through a new force. In the simplest model, the new interaction is mediated by a massive vector particle, also called ``dark photon'' ($A^\prime$), kinetically mixed with the ordinary photon.

The NA64-$e$ experiment at CERN North Area conducts a dedicated search for Light Dark Matter by running a missing energy measurement with high energy electron and positron beams from SPS impinging on a active thick target.
With a total statistics of about $10^{12}$ electrons-on-target already accumulated during the 2016-2022 period, NA64$-e$ was able to probe for the first time the target region of the parameter space motivated by cosmology for scalar and Majorana LDM, in the $A^\prime$ mass range between 1 MeV and 100 MeV.

In parallel to the main electron-beam program, NA64$-e$ recently completed a first pilot run with a 100 GeV positron beam. The goal of the test was to experimentally demonstrate this new technique, characterized by an enhanced $A^\prime$ production by resonant annihilation of positrons with atomic electrons. With a total accumulated statistics of about $10^{10}$ positrons on target, the pilot run allowed NA64$-e$ to set competitive exclusion limits in the LDM parameter space.

This document provides a summary of the latest results obtained by the aforementioned NA64$-e$ efforts, together with a description of the future plans for the experiment.
DOI: https://doi.org/10.22323/1.457.0014
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