Muon g-2 from Millicharged Hidden Confining Sector

Understand

We provide a novel explanation to the muon $g-2$ excess with new physics contributions at the two-loop level.

• In this scenario, light millicharged particles are introduced to modify the photon vacuum polarization that contributes to muon $g-2$ at one additional loop.
• The muon $g-2$ excess can be explained with the millicharged particle mass $m_\chi$ around 10 MeV and the product of the multiplicity factor and millicharge squared of $N_\chi \varepsilon^2 \sim 10^{-3}$.
• The minimal model faces severe constraints from direct searches at fixed-target experiments and astrophysical observables.