2918779 SzGeCERN 20241204215341.0 DOI SISSA 10.22323/1.457.0014 oai:cds.cern.ch:2918779 cerncds:FULLTEXT cerncds:CERN:FULLTEXT cerncds:CERN https://inspirehep.net/api/oai2d 2024-12-04T06:10:31Z marcxml oai:inspirehep.net:2777475 2024-12-03T14:10:20Z Inspire 2777475 eng Celentano, Andrea andrea.celentano@ge.infn.it INFN, Genoa SISSA Dark sector searches at NA64-$e$ 2024 6 p SISSA 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. CC-BY-NC-ND-4.0 SISSA https://creativecommons.org/licenses/by-nc-nd/4.0/ SzGeCERN Nuclear Physics - Experiment SzGeCERN Particle Physics - Experiment ARTICLE CERN CERN SPS NA64 NA64 Collaboration 014 C23-11-08.1 2024 PoS WIFAI2023 2693584 480414 http://cds.cern.ch/record/2918779/files/document.pdf Fulltext 13 2887103 rome20231108 014 ARTICLE ConferencePaper