Missing energy signals such as monojets are a possible signature of dark matter (DM) at colliders. However, neutrino interactions beyond the Standard Model may also produce missing energy signals. In order to conclude that new “missing particles” are observed, the hypothesis of beyond the Standard Model neutrino interactions must be rejected. In this paper, we first derive new limits on these nonstandard neutrino interactions (NSIs) from LHC monojet data. For heavy NSI mediators, these limits are much stronger than those coming from traditional low-energy $\nu$ scattering or $\nu$ oscillation experiments for some flavor structures. Monojet data alone can be used to infer the mass of the missing particle from the shape of the missing energy distribution. In particular, 13 TeV LHC data will have sensitivity to DM masses greater than $\sim 1\mathrm{TeV}$. In addition to the monojet channel, NSI can be probed in multilepton searches which we find to yield stronger limits at heavy mediator masses. The sensitivity offered by these multilepton channels provides a method to reject or confirm the DM hypothesis in missing energy searches.

• Received 9 February 2016

DOI:https://doi.org/10.1103/PhysRevD.93.095001