Missing energy signatures of inelastic magnetic dipole DM at NA64e

TL;DR

This paper calculates the potential of the NA64e experiment at CERN to detect inelastic magnetic dipole dark matter particles through their production in high-energy electron-nucleus interactions, exploring new parameter space regions.

Contribution

It introduces a detailed calculation of iDM production rates and projected sensitivities for NA64e, including heavy vector meson decay channels, to enhance detection prospects.

Findings

NA64e can probe previously unexplored iDM parameter space.

Heavy vector meson decays significantly extend detection sensitivity.

Projected sensitivity assumes 10^13 electrons on target at 100 GeV.

Abstract

Some extensions of the Standard Model consider inelastic dark matter (iDM) as an attractive candidate for sub-GeV DM of thermal origin that could be detected at modern accelerators. In the present paper, we calculate the production rate of iDM pairs $\chi_{1} \bar{\chi}_0$ interacting with the ordinary photon via dipole magnetic moment in the reaction of high-energy electron scattering on nuclei, $e^- N \to e^- N \chi_{1} \bar{\chi}_0$, in the NA64e experiment at the CERN SPS. We derive the projected sensitivity of NA64e to such particles assuming of $\simeq10^{13}$ 100 GeV electrons on target. We also show, that incorporating heavy vector meson decays, $\gamma^* N \to N V (\to \chi_1 \bar{\chi}_0)$, alongside bremsstrahlung-like emission of inelastic dark matter pairs, $e^- N \to e^- N \gamma^* (\to \chi_1 \bar{\chi}_0)$, will allow NA64e to probe previously unexplored regions of the iDM parameter space, in particular for modest mass splittings, $\Delta \simeq 5 \times 10^{-2}$, and relatively light masses, $m_{\chi_0} \lesssim 100~\mbox{MeV}$.