Z ′ - mediated slepton and sneutrino signatures at the HL-LHC

We investigate the discovery potential of a heavy $Z'$ boson as a portal to charged sleptons and right-handed sneutrinos within the $B-L$ Supersymmetric Standard Model (BLSSM) at the High-Luminosity LHC. Using a detector-level simulation and Boosted Decision Trees to suppress Standard Model backgrounds, we find that the direct slepton decay pp → Z' → ̃⁺̃⁻ → 2 + ETᵐⁱˢˢ yields a significance exceeding $5σ$ at 3000 fb⁻¹, while the cascade (multileptons + ETᵐⁱˢˢ) mode is unobservable due to rate suppression. For right-handed sneutrinos, the hadronic channel pp → Z' → νRνI → 2 + 4j + E Tᵐⁱˢˢ emerges as the most promising signature. These results establish the 2 + ETᵐⁱˢˢ and 2 + 4j + ETᵐⁱˢˢ final states as the principal discovery channels for the scalar leptonic sector of the BLSSM at the HL-LHC.