Right-handed sneutrino dark matter in $\mathbf{U(1)'}$ seesaw models and its signatures at the LHC

TL;DR

This paper proposes a right-handed sneutrino as a dark matter candidate within a supersymmetric $Z'$ model that incorporates the seesaw mechanism, and explores its detection prospects at the LHC through specific signatures involving $Z'$ and neutrinos.

Contribution

It introduces a novel dark matter candidate in a supersymmetric $Z'$ seesaw model and analyzes its relic density and collider signatures, including potential Higgs discovery channels.

Findings

Thermal freeze-out of sneutrino dark matter can match observed density.

LHC signatures include $pp o ilde Z' ilde Z' o NN + ot{p}_T$ processes.

Displaced $N$ decays could provide a new Higgs detection channel.

Abstract

We suggest a real right-handed sneutrino, $\tilde N_1$, as a good dark matter candidate in a supersymmetric $Z'$ model realizing the seesaw mechanism. When the extra gaugino, $\tilde Z'$, is lighter than $Z'$, the thermal freeze-out of the dark matter annihilation to right-handed neutrinos, $ \tilde{N}_1 \tilde{N}_1 \to NN$, through the $t$-channel $\tilde Z'$ exchange is shown to produce the right dark matter density. It is essential to include the decay and inverse decay of $N$ in this process, otherwise $N$ decouples too early and thus dark matter is overproduced. At the LHC, the search for the seesaw mechanism can be made by observing the signatures of $pp \to \tilde Z' \tilde Z' \to NN + \ptmiss$ as $\tilde Z'$ can be copiously produced from the cascade decays of gluinos/squarks, which is complementary to the search of $pp\to Z' \to NN$. This may also open up a promising new channel of finding the Higgs boson from the displaced $N$ decay.