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arXiv · 2106.15626

Muon g-2 from Millicharged Hidden Confining Sector

Yang Bai·Seung J. Lee·Minho Son·Fang Ye
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Abstract

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. However, if the millicharged particles are also charged under a hidden confining gauge group $SU(N_\chi)$ with a confinement scale of MeV, hidden-sector hadrons are unstable and can decay into neutrinos, which makes this scenario consistent with existing constraints. This explanation can be well tested at low-energy lepton colliders such as BESIII and Belle II as well as other proposed fixed-target experiments.

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Yang Bai, Seung J. Lee, Minho Son, Fang Ye. 2021-06-29. Muon g-2 from Millicharged Hidden Confining Sector. https://doi.org/10.1007/jhep11(2021)019

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