Speaker
Description
The recent $(g-2)_\mu$ measurement by the E989 experiment at Fermilab has recently confirmed the previous results at the Brookhaven experiment. The current tension between experiment and the Standard Model (SM) predictions stands at $4.2~\sigma$. In light of this tantalizing result, it is tempting to reconsider the few low-energy extensions of the SM that may explain the discrepancy. In particular, we revisit the contribution of a kinetically mixed dark photon to the $(g-2)_\mu$, which has been excluded in minimal models with fully visible and invisible dark photon decays. By explicitly re-evaluating constraints from B-factories and fixed target experiments, we show that dark photons with semi-visible decays can still explain the $(g-2)_\mu$ puzzle. Such solution would point to dark sectors with co-annihilating dark matter candidates or dark neutral leptons with fast decays
