Probing the Weinberg operator at colliders
Benjamin Fuks, J. Neundorf, Κ. Peters, Richard Ruíz, M. Saimpert
Abstract
Motivated by searches for $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ decay in nuclear experiments and collider probes of lepton number violation at dimension $d\ensuremath{\ge}7$, we investigate the sensitivity to the $d=5$ Weinberg operator using the nonresonant signature $pp\ensuremath{\rightarrow}{\ensuremath{\ell}}^{\ifmmode\pm\else\textpm\fi{}}{{\ensuremath{\ell}}^{\ensuremath{'}}}^{\ifmmode\pm\else\textpm\fi{}}jj$ at the LHC. We develop a prescription for the operator that is applicable in collisions and decays, and focus on the $\ensuremath{\ell}{\ensuremath{\ell}}^{\ensuremath{'}}=\ensuremath{\mu}\ensuremath{\mu}$ channel, which is beyond the reach of nuclear decays. For a Wilson coefficient ${C}_{5}^{\ensuremath{\mu}\ensuremath{\mu}}=1$, scales as heavy as $\mathrm{\ensuremath{\Lambda}}\ensuremath{\sim}8.3(11)\text{ }\text{ }\mathrm{TeV}$ can be probed with $\mathcal{L}=300\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}(3\text{ }\text{ }{\mathrm{ab}}^{\ensuremath{-}1})$. This translates to an effective $\ensuremath{\mu}\ensuremath{\mu}$ Majorana mass of $|{m}_{\ensuremath{\mu}\ensuremath{\mu}}|\ensuremath{\sim}7.3(5.4)\text{ }\text{ }\mathrm{GeV}$ and establishes a road map for testing the Weinberg operator at accelerators.