Speaker
Description
Increasing attention has been given recently to the theory and phenomenology of portal matter (PM) models — a BSM framework in which the standard model (SM) local gauge symmetry group is augmented by a local dark group $U(1)_D$, of which the mediator is the dark photon, and kinetic mixing between $U(1)_D$ and the SM hypercharge is generated at one loop by the PM fields. The case in which the PM are vector-like leptons (VLL) is of particular interest for the study of precision measurements of the leptonic sector: We have recently studied a simple realization of this $U(1)_D$ model that addresses the potential $(g-2)_\mu$ anomaly [1] and a TeV-scale completion in which the $U(1)_D$ is embedded into a larger non-Abelian dark group, allowing the SM and PM fields to exist as members of the same dark gauge multiplets [2] and resulting in the introduction of new $U(1)_D$-neutral vector-like leptons. Here we study models with leptonic PM and additional $U(1)_D$ neutral vector-like leptons. We analyze the minimal particle content that such a simplified model can have and still produce a sizable correction to the charged lepton flavor-conserving process $(g-2)_\mu$, which shows that only certain combinations of PM and $U(1)_D$-neutral VLL are required, in agreement with [3]. Moreover, given the current stringent constraints on muonic charged lepton flavor violation (CLFV), we study the CLFV processes $\mu^+ \rightarrow e^+ + \gamma $, $\mu^+ \rightarrow e^+ + e^- + e^+$, and $\mu$ to $e$ conversion in nuclei up to one loop level and examine how current and future experiments can constrain its parameter space [4].
[1] George N. Wojcik, Lisa L. Everett, Shu Tian Eu, and Ricardo Ximenes. "Portal Matter, Kinetic Mixing, and Muon g-2." Physics Letters B 841 (2023): 137931.
[2] George N. Wojcik, Lisa L. Everett, Shu Tian Eu, and Ricardo Ximenes. "Lepton flavor portal matter." Physical Review D 108.5 (2023): 055033.
[3] George N. Wojcik, Shu Tian Eu, and Lisa L. Everett. "Graph reinforcement learning for exploring model spaces beyond the standard model." Physical Review D 111.3 (2025): 035007.
[4] George N. Wojcik, Lisa L. Everett, Shu Tian Eu, and Ricardo Ximenes. "Charged Lepton Flavor Violation in a Lepton Flavor Portal Matter Model" - In preparation.
