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22–26 Sep 2025
Asia/Shanghai timezone

Linearly Polarized Photon Fusion as a Precision Probe of the Tau Lepton Dipole Moments at Lepton Colliders

Not scheduled
20m
Oral Fundamental symmetries and spin physics beyond the standard model Parallel

Speaker

Fang Xu (复旦大学)

Description

We present a comprehensive investigation into the anomalous magnetic dipole moment ($a_\tau$) and electric dipole moment ($d_\tau$) of the $\tau$ lepton using the $\gamma\gamma \to \tau^+\tau^-$ process at future lepton colliders, with the Super Tau-Charm Facility serving as a benchmark. By employing transverse-momentum-dependent factorization, we introduce novel observables derived from $\cos2\phi$, $\sin2\phi$, and $\cos4\phi$ azimuthal asymmetries to precisely probe the $\tau$ lepton's electromagnetic structure. Our analysis significantly enhances the precision of $a_\tau$ constraints within the photon-photon fusion process, yielding $\mathrm{Re}(a_\tau) \in [-4.5, 6.9] \times 10^{-3}$ at the $2\sigma$ confidence level, which approaches the precision of the Standard Model prediction. These findings highlight the considerable potential of azimuthal asymmetry measurements for high-precision determinations of fundamental particle properties at future lepton colliders.

Primary author

Fang Xu (复旦大学)

Co-authors

Dingyu Shao (CERN, Theoretical Physics Department) Bin Yan (IHEP) Cheng Zhang (杭州师范大学) Hao Xiang (Fudan University)

Presentation materials

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