DREAMuS: Dark matter REsearch with Advanced Muon Source

TL;DR

DREAMuS is a proposed fixed-target experiment at HIAF aiming to detect muon-philic dark matter mediated by light bosons, utilizing precision measurements to explore new parameter space.

Contribution

It introduces a novel experimental setup, DREAMuS, designed to probe light flavor-violating bosons mediating muon-philic dark matter with improved sensitivity.

Findings

DREAMuS can reach sensitivity to couplings of 10^{-4} in the GeV-scale dark matter parameter space.

A muon-plus beam option could improve sensitivity below 200 MeV by an order of magnitude.

The experiment employs precision tracking and time-of-flight to suppress Standard Model backgrounds.

Abstract

We propose DREAMuS, a fixed-target experiment at the High Intensity Heavy-Ion Accelerator Facility (HIAF), to search for muon-philic dark matter mediated by light flavor-violating bosons. DREAMuS is designed to probe the parameter space of a muon-philic dark matter (DM) mediated by a light flavor-violating boson, specifically a vector $Z'$ (or a scalar $\phi$) which is produced in muon-nucleus interactions and decays into dark matter particles with a distinctive detector signature. Precision tracking and time-of-flight measurements are used to suppress the Standard Model backgrounds. We find that DREAMuS can achieve competitive sensitivity in the GeV-scale muon-philic dark matter parameter space, reaching sensitivity to couplings at the $10^{-4}$, especially in the few-hundred-MeV region.In addition to a $\mu^-$ run, we highlight the potential of a complementary $\mu^+$ beam option, further improving sensitivity to dark matter below 200 $\mathrm{MeV}$ by an order of magnitude.