Lepton flavor violation in Higgs boson decays at the HL-LHC

Abstract

We explore the discovery potential for lepton flavor-violating Higgs boson decays, $h\to {\ell }_i{\ell }_j$ (${\ell }_i\ne {\ell }_j$; $\ell =e,\mu ,\tau$), in proton-proton collisions. The analysis is performed within a Froggatt-Nielsen framework, which offers a well-motivated theoretical mechanism for such processes. By performing a systematic scan over the phenomenologically viable parameter space, we identify regions that can yield observable signatures at the High-Luminosity LHC (HL-LHC). For an integrated luminosity of ${\mathcal{L}}_{\mathrm{int}}\gtrsim 1000{\text{fb}}^{-1}$, we project that the channels $h\to e\mu$ and $h\to \tau \mu$ (with ${\tau }^{\pm }\to {\pi }^{\pm }{\nu }_{\tau }$) could reach the $5\sigma$ discovery threshold, while $h\to \tau e$ remains inaccessible even at $3000{\text{fb}}^{-1}$. Our results highlight the unique capability of the HL-LHC to probe new physics through searches for rare Higgs decays.

Comments: Version accepted for publication in JHEP