Light neutralino dark matter in $U(1{)}^{\prime }$ models

We analyze the prospects for light neutralino dark matter in the minimal supersymmetric model extended by a $U(1)$ gauge group. We allow the neutralino to be an arbitrary admixture of singlet and doublet Higgsinos, as well as of the three gauginos, and we require agreement with the data from the direct and indirect dark matter detection experiments, while maintaining consistency of the model with the relic density, and with the recent Higgs data from the LHC. The constraints have implications for the structure of the lightest neutralino as a dark matter candidate, indicating that it is largely singlino, and its mass can be as light as $\sim 20\mathrm{GeV}$.

Figure 1

Relic density distribution as a function of the neutralino DM mass. The horizontal band represents the $3\sigma$ allowed range of relic density: $0.128\ge \mathrm{\Omega }{h}^2\ge 0.1118$. The red points show the general features of the distribution and the blue points are obtained after imposing the HiggsBounds constraint in addition to $BR(h_{2_{\text{inv}}})<58\%$, where $h_2$ is the SM-like Higgs boson in the theory.

Figure 2

Spin-independent cross section as a function of the neutralino DM mass. The black line and magenta lines represent most recent exclusion lines provided by LUX and ATLAS experiments, respectively. The gray points show the general features, the red (and blue) points satisfy DM (and Higgs) constraints while the green ones satisfy both simultaneously.

Figure 3

Annihilation cross section as a function of the neutralino DM mass. The color codes are the same as before. Gray points show the general feature, blue points satisfy HiggsBounds and invisible decay width constraints, red points satisfy the relic density constraint and the green ones satisfy both these and other collider constraints simultaneously.

Figure 4

The dominant components of the LSP neutralino, the singlino component on the $x$ axis, and the up-type Higgsino on the $y$ axis. The LSP must be dominantly singlino, as explained in the text. The gray points show the general features, the red points satisfy DM constraints, while the green ones satisfy both the collider and DM constraints.

Figure 5

The lighter chargino mass plotted against the lightest Higgs mass in the model. Red points satisfy Higgs invisible branching ratio decay constraints while the green ones satisfy both collider and DM constraints.

Figure 6

Left panel: The Higgs boson signal strengths in gauge boson decay channels (${\mu }_{WW}$ and ${\mu }_{ZZ}$) for the corresponding parameter space shown in the plot. Right panel: The Higgs boson signal strengths in fermion antifermion decay channels (${\mu }_{bb}$ and ${\mu }_{\tau \tau }$) for the corresponding parameter space shown in the plot. The red points correspond to $BR(h_{2_{\text{inv}}})<58\%$. The points which satisfy HiggsBounds are shown in blue. The green points are the ones which satisfy all the constraints simultaneously. The shaded regions are the $1\sigma$ allowed ranges for the respective signal strength values as quoted by the CMS collaboration.

Figure 7

Correlation between $BR(h_{2_{\mathrm{inv}}})$ and ${\mu }_{\gamma \gamma }$. The red points satisfy HiggsBounds constraints and the green points simultaneously satisfy all the collider and DM constraints. The dark shaded region is the $1\sigma$ allowed range and the light shaded region is the $2\sigma$ allowed range for the $\gamma \gamma$ signal strength values as quoted by the CMS collaboration.