Leptonic scalars at the LHC
André de Gouvêa, P. S. Bhupal Dev, Bhaskar Dutta, Tathagata Ghosh, Tao Han, Yongchao Zhang
Abstract
A bstract We explore the collider prospects of neutrino non-standard interaction with a Standard Model (SM) gauge-singlet leptonic scalar ϕ carrying two units of lepton-number-charge. These leptonic scalars are forbidden from interacting with the 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 characteristic production signature at hadron collider experiments like the LHC would be via the vector boson fusion process and leads to same-sign dileptons, two forward jets in opposite hemispheres, and missing transverse energy, i.e., $$ pp\to {\mathrm{\ell}}_{\alpha}^{\pm }{\mathrm{\ell}}_{\beta}^{\pm } jj+{E}_T^{\mathrm{miss}}\left(\alpha, \beta =e,\mu, \tau \right) $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>pp</mml:mi> <mml:mo>→</mml:mo> <mml:msubsup> <mml:mi>ℓ</mml:mi> <mml:mi>α</mml:mi> <mml:mo>±</mml:mo> </mml:msubsup> <mml:msubsup> <mml:mi>ℓ</mml:mi> <mml:mi>β</mml:mi> <mml:mo>±</mml:mo> </mml:msubsup> <mml:mi>jj</mml:mi> <mml:mo>+</mml:mo> <mml:msubsup> <mml:mi>E</mml:mi> <mml:mi>T</mml:mi> <mml:mtext>miss</mml:mtext> </mml:msubsup> <mml:mfenced> <mml:mi>α</mml:mi> <mml:mrow> <mml:mi>β</mml:mi> <mml:mo>=</mml:mo> <mml:mi>e</mml:mi> </mml:mrow> <mml:mi>μ</mml:mi> <mml:mi>τ</mml:mi> </mml:mfenced> </mml:math> . 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 LHC sensitivity is largely complementary to that of low-energy precision measurements of the decays of charged leptons, charged mesons, W , Z and the SM Higgs boson, as well as the neutrino beam experiments like MINOS, and searches for neutrino self-interactions at IceCube and in cosmological observations. For ϕ mass larger than roughly 10 GeV, our projected LHC sensitivity would surpass all existing bounds.