Observation of nonzero neutrino masses at a scale $\sim 10^{-1}–10^{-2}\mathrm{eV}$ is a major problem in the otherwise highly successful Standard Model. The most elegant mechanism to explain such tiny neutrino masses is the seesaw mechanism with right-handed neutrinos. However, the required seesaw scale is so high, $\sim {10}^{14}\mathrm{GeV}$, it will not have any collider implications. Recently, an explicit model has been constructed to realize the seesaw mechanism with the right-handed neutrinos at the electroweak scale. The model has a mirror symmetry, having both the left and right lepton and quark doublets and singlets for the same $SU(2{)}_W$ gauge symmetry. Additional Higgs multiplets have been introduced to realize this scenario. It turns out that these extra Higgs fields also help to satisfy the precision electroweak tests, and other observables. Because the scale of the symmetry breaking is electroweak, both the mirror quark and the mirror leptons have masses in the electroweak scale in the range $\sim 150–800\mathrm{GeV}$. The mirror quarks/leptons decay to ordinary quarks/leptons plus very light neutral scalars. In this work, we calculate the final-state signals arising from the pair productions of these mirror quarks and their subsequent decays. We find that these signals are well observable over the Standard Model background for the 13 TeV LHC. Depending on the associated Yukawa couplings, these decays can also give rise to displaced vertices with long decay lengths, very different from the usual displaced vertices associated with b decays.

• Received 25 September 2015

DOI:https://doi.org/10.1103/PhysRevD.93.035007