Multicomponent dark matter from a hidden gauged SU(3)

We study Dark Matter (DM) phenomenology with multiple DM species consisting of both scalar and vector DM particles. More specifically, we study the hidden gauged SU(3) model of Arcadi et al. Before proceeding to the hidden gauged SU(3) model, we study the relic abundances of simplified multispecies DM scenarios to gain some insights when multiple species and interactions are included. In the hidden gauged SU(3) model, because of the large parameter space, we restrict ourselves to three representative benchmark points, each with multiple DM species. The relic densities for the benchmark points were found using a program developed to solve the coupled Boltzmann equations for an arbitrary number of interacting DM species with two particles in the final state. For each case, we varied the mass of the DM particles and then found the value of the dark SU(3) gauge coupling that gives the correct relic density. We found that for some sets of parameter values DM would be difficult to observe in direct detection experiments but would be easier to observe in indirect detection experiments while for other sets of parameter values the situation was reversed so that measurements from both types of experiments complement each other and could help pinpoint the details of the hidden SU(3) model. Important to this is that, even for moderate changes in input parameter values, the relative relic density of each species can change significantly, resulting in large changes in the observability of multispecies DM by direct or indirect detection.

Figure 1

DM number densities as a function of $x=m/T$ for three DM species. The solid curves represent the equilibrium density; the dashed curves represent the scenario with only self-annihilation to SM particles, which we label as the base; the curves with both dots and dashes represent scenarios with the base interactions plus a single additional interaction as labeled in the plot; and the dotted curve represent the result including all the additional interactions of the previous curves. The green, blue, and red curves represent the number density of ${\varphi }_1$, ${\varphi }_2$, and ${\varphi }_3$ with masses of 100, 120, and 150 GeV, respectively. Note that for the green and blue curves, the various curves sit very closely on top of each other.

Figure 2

DM number densities as a function of $x=m/T$ for four DM species. The line labeling is as in Fig. 1. The green, blue, red, and purple curves represent the number density of ${\varphi }_1$, ${\varphi }_2$, ${\varphi }_3$, and ${\varphi }_4$ with masses of 100, 120, 150, and 180 GeV, respectively. Note that for the green, blue, and red curves the various curves sit very closely on top of each other.

Figure 3

Constraints on the allowed SU(3) gauge coupling values and the resulting ratio of the vector relic density to total relic density as a function of the DM mass. The left column shows values of the gauge coupling required so that the relic density is consistent with ${\mathrm{\Omega }}_{\mathrm{CDM}}{h}^2=0.1186\pm 0.002$, while the right column shows the fraction of DM that consists of vector particles. The dashed lines in the left column show the unitarity bound for $\tilde{g}$ which is $\sqrt{4\pi }$, and the dashed lines in the right column show the maximum value that $f_A$ can take, which is 1. Plots (a) and (b) show the results for scenario A, plots (c) and (d) show the results for scenario B, and plots (e) and (f) show the results for scenario C.

Figure 4

The direct detection event rate as a function of the DM mass. Plots (a), (b), and (c) show the results for benchmark points A, B and C, respectively. The allowed points are below the dashed line at $1.58\times {10}^{-4}{\mathrm{kg}}^{-1}{\mathrm{day}}^{-1}$. In all the cases, the regions where the coupling constant $\tilde{g}$ was large to give the allowed relic density are ruled out by these direct detection constraints. These are also the regions where a significant portion of the DM is composed of scalars.

Figure 5

Indirect detection constraints for the $W^{+}{W}^{-}$ final state. (a), (b), and (c) show the results for benchmark points A, B, and C, respectively. The line colors are as follows: red for $\chi \chi \to W^{+}{W}^{-}$; blue for $\mathcal{H}\mathcal{H}\to W^{+}{W}^{-}$; green for $A^{1^{\prime }}{A}^{1^{\prime }}\to W^{+}{W}^{-}$ or $A^{2^{\prime }}{A}^{2^{\prime }}\to W^{+}{W}^{-}$, which have identical results; purple for $A^{3^{\prime }}{A}^{3^{\prime }}\to W^{+}{W}^{-}$; and orange for $A^{4^{\prime }}{A}^{4^{\prime }}\to W^{+}{W}^{-}$ or $A^{5^{\prime }}{A}^{5^{\prime }}\to W^{+}{W}^{-}$, which have identical results. The dashed lines are the constraints from Fermi [55], while the solid lines are the predictions of the model. Note that the purple and green dashed lines are almost superimposed because they have very similar masses leading to similar constraints. We also note that the solid orange line does not appear because it is too small.