Phenomenology of $U(1)_{L_μ- L_τ}$ charged dark matter at PAMELA/FERMI and colliders
Seungwon Baek, Pyungwon Ko
TL;DR
This work analyzes a leptophilic dark matter scenario based on gauged $U(1)_{L_\mu-L_\tau}$, introducing a DM Dirac fermion $\psi_D$ and a complex scalar $\phi$ that generate a massive $Z'$ mediator. The study links the muon anomalous magnetic moment, thermal relic density, and collider phenomenology, showing viable regions where $M_{Z'}$, $\alpha'$, and $M_{\psi_D}$ satisfy the $(g-2)_\mu$ constraint and yield the observed relic density while evading current collider bounds. Indirect-detection signals require substantial Sommerfeld enhancement (BF ~ $10^3$), which can be realized with the light $Z'$ mediator, producing predictive neutrino and gamma-ray flux patterns that depend on the DM profile. At colliders, $Z'$ production can yield $O(1)$–$O(10^3)$ fb cross sections, with final states dominated by multi-muon or multi-tau events and missing energy; the LHC, with sufficient luminosity, can probe much of the viable parameter space. The model further allows Higgs–scalar mixing that can open exotic decays like $H_i\to Z'Z'$ and $H_2\to H_1H_1$, potentially featuring large invisible BRs and rich collider phenomenology.
Abstract
Recent data on $e^+/e^-$ and $\bar{p}$ cosmic rays suggest that dark matter annihilate into the standard model (SM) particles through new leptophilic interaction. In this paper, we consider a standard model extension with the gauged $U(1)_{L_μ- L_τ}$ group, with a new Dirac fermion charged under this U(1) as a dark matter. We study the muon $(g-2)_μ$, thermal relic density of the cold dark matter, and the collider signatures of this model. $Z^{'}$ productions at the Tevatron or the LHC could be easily order of $O(1)-O(10^3)$ fb.