Accidental scale-invariant Majorana dark matter in leptoquark-Higgs portals

Abstract

We study a classically accidental scale-invariant extension of the Standard Model (SM) containing three additional fields, a vector leptoquark ($V_{\mu }$), a real scalar ($\varphi$), and a neutral Majorana fermion ($\chi$) as a dark matter (DM) candidate. The scalar $\varphi$ (scalon) and Majorana fermion $\chi$ are both singlets under the SM gauge group, while $V_{\mu }$ has (\textbf{3}, \textbf{1}, 2/3) quantum numbers under the $SU(3{)}_c\times SU(2{)}_L\times U(1{)}_Y$. The Majorana DM couples to the SM sector via both Higgs and leptoquark portals. We perform a scan over the independent parameters to determine the viable parameter space consistent with the Planck data for DM relic density, and with the PandaX-II and LUX direct detection limits for the spin-independent (SI) and spin-dependent (SD) DM-nucleon cross section. The model generally evades indirect detection constraints while being consistent with collider data.

20 pages, 7 figures, version accepted for publication in Nuclear Physics B