Searching for light Dark Matter with NA64-e and POKER at CERN

Abstract

Light dark matter (LDM) is a theoretically well motivated model providing an attractive explanation for the observed relic dark matter density. In this scenario, LDM is composed of sub-GeV particles, feebly interacting with ordinary matter via a new force. NA64-e is a missing energy experiment at CERN Super Proton Synchrotron (SPS), aiming to produce LDM particles using the 100-GeV SPS electron beam impinging on a thick, active target (electromagnetic calorimeter). Each impinging electron is tagged and its momentum is measured; the LDM production signature consists in a large difference between the initial electron energy and the measured energy deposition in the calorimeter. In last years, NA64-e collected data also with a positron beam, in order to exploit the e+−e− resonant annihilation process for the Aproduction, synergistically with the POKER (POsitron resonant annihilation into darK mattER) project. POKER is an ERC-funded effort, whose aim is to perform a preliminary missing-energy measurement with a multi-energy positron beam. POKER will exploit the NA64−e experimental setup, using a new high-resolution PbWO4 electromagnetic calorimeter as an active target. This document presents the status of the NA64-e experiment, its latest results and future prospects. Advances in the POKER program are reported, with a focus on the analysis of the latest positron data-takings performed during 2022 and 2023