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arXiv · 2508.20873

Vectorlike lepton imprints at lepton $g-2$ measurements and $e^+e^-$ colliders

Sang Quang Dinh·Hieu Minh Tran
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Abstract

A fermion can be chiral or vectorlike with respect to a given symmetry, depending on its coupling to the corresponding gauge boson. Vectorlike fermions have a distinct property that their left-handed and right-handed components behave in the same way under the gauge symmetry. In this paper, we investigate an extension of the standard model with an $SU(2)$ doublet of vectorlike leptons and two complex scalars. The new physics effects on the lepton anomalous magnetic moment, as well as the electron and muon pair production processes at $e^+e^-$ colliders are analyzed. Taking into account the updated measurement results of the electron and muon $g-2$, the LEP and the LHC data, the viable parameter space of the model is identified. We also examine the prospect of testing the model using $\mu^+\mu^-$ signals from electron-position annihilation at the Future Circular Collider (FCC-ee). The analysis shows that the FCC-ee will be able to exclude a significant part of the parameter space, pinpointing exiguous viable regions to be tested in the future due to its high precision.

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Sang Quang Dinh, Hieu Minh Tran. 2025-08-28. Vectorlike lepton imprints at lepton $g-2$ measurements and $e^+e^-$ colliders. https://doi.org/10.1103/w45p-zqx4

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