Prospects of type-II seesaw at future colliders in light of the DAMPE $e^{+}{e}^{-}$ excess

Abstract

The DAMPE $e^{+}{e}^{-}$ excess at around 1.4 TeV could be explained in the type-II seesaw model with a scalar dark mater $D$ which is stabilized by a discrete $Z_2$ symmetry. The simplest scenario is the annihilation $DD\to H^{++}{H}^{--}$ followed by the subsequent decay $H^{\pm \pm }\to e^{\pm }{e}^{\pm }$, with both the DM and triplet scalars roughly 3 TeV with a small mass splitting. In addition to the Drell-Yan process at future 100 TeV hadron colliders, the doubly-charged components could also be produced at lepton colliders like ILC and CLIC in the off-shell mode, and mediate lepton flavor violating processes $e^{+}{e}^{-}\to {\ell }_i^{\pm }{\ell }_j^{\mp }$ (with $i\ne j$). A wide range of parameter space of the type-II seesaw could be probed, which are well below the current stringent lepton flavor constraints.

Comments: 9 pages, 5 figures, minor changes, version to appear in PRD