Leptonic Scalars at the LHC
Andre de Gouvea, P. S. Bhupal Dev, Bhaskar Dutta, Tathagata Ghosh, Tao Han, Yongchao Zhang
We explore the neutrino non-standard interaction with leptonic scalars ϕ which are gauge-singlets and carry two units of lepton-number-charge. These leptonic scalars are forbidden from interacting with the Standard Model (SM) fermions at the renormalizable level and, if one allows for higher-dimensional operators, couple predominantly to SM neutrinos. For masses at or below the electroweak scale, ϕ decays exclusively into neutrinos. Its unique production signature at hadron collider experiments like the LHC would be via the vector boson fusion process and lead to same-sign dileptons, two forward jets in opposite hemispheres, and missing transverse energy, i.e., pp→ℓ±αℓ±βjj+EmissT (α,β=e,μ,τ). Exploiting the final states of electrons and muons, we estimate, for the first time, the sensitivity of the LHC to these lepton-number-charged scalars. We show that, the sensitivity of high-energy colliders is largely complementary to that of low-energy and precision measurements of the decays of charged leptons, charged mesons, W and Z bosons, neutrino beam experiments like MINOS, searches for light dark matter in NA64, and searches for neutrino self-interactions at IceCube and in cosmological observations. For ϕ mass larger than a few GeV, our projected LHC sensitivity would surpass all existing bounds.