Resurrecting $L$-type sneutrino dark matter in light of neutrino masses and LUX data

In the minimal supersymmetric standard model (MSSM) the lightest superpartner of the left-handed neutrinos is ruled out as a candidate for dark matter because of its large elastic cross section with the nucleus mediated via the $Z$ boson. We resurrect this candidate by extending the MSSM with two triplets with opposite hypercharge. The addition of the triplets not only plays the role of generating small Majorana masses for the left-handed active neutrinos, but it also makes the lightest sneutrino a viable candidate for dark matter. We then discuss the relevant parameter space that can give rise to the right amount of (thermal) relic abundance as well as satisfy the current direct-detection constraints from XENON100 and LUX. We find that sneutrino dark matter with mass 370–550 GeV can give rise to the correct thermal relic abundance while coannihilating with the bino-like neutralino.

Figure 1

Majorana mass of neutrinos generated through the one-loop radiative correction.

Figure 2

Allowed values of $r_1$ and $r_2$ are shown for all values of $0<R<10^{-5}$. The blue and pink lines correspond to $R=10^{-5}$ and $R=0$, respectively. We have assumed a pure bino-like state with mass $|M_1|$ and a pure wino-like state with mass $M_2$.

Figure 3

The variation of the thermal relic density of ${\tilde{\nu }}_1$ DM, as a function of its mass and the mass difference with a bino-like ${\tilde{\chi }}_1^0$.

Figure 4

Relic abundance for ${\tilde{\nu }}_1$ dark matter. The green dots represent a scenario where no additional coannihilation is present, while the blue dots represent a coannihilation scenario with a bino-like ${\tilde{\chi }}_0^1$. The bino mass parameter $|M_1|$ has been assumed to be 5 GeV above $M_{\mathrm{DM}}$ in the latter scenario.

Figure 5

The left panel shows the cross section of the ${\tilde{\nu }}_{\tau }$ DM with a neutron as a function of its mass. Note that this includes the $Z$-boson-exchange processes. In the right panel, the blue line shows the Higgs-exchange elastic cross section of ${\tilde{\nu }}_1$ DM with a nucleon, while the green line corresponds to the experimental bound from LUX.