Detection prospects of singlet fermionic dark matter

A singlet fermion which interacts only with a new singlet scalar provides a viable and minimal scenario that can explain the dark matter. The singlet fermion is the dark matter particle whereas the new scalar mixes with the Higgs boson providing a link between the dark matter sector and the standard model. In this paper, we present an updated analysis of this model focused on its detection prospects. Both the parity-conserving case and the most general case are considered. First, the full parameter space of the model is analyzed, and the regions compatible with the dark matter constraint are obtained and characterized. Then, the implications of current and future direct detection experiments are taken into account. Specifically, we determine the regions of the multidimensional parameter space that are currently excluded and those that are going to be probed by next generation experiments. Finally, indirect detection prospects are discussed and the expected signal at neutrino telescopes is calculated.

Figure 1

The region in the plane ($M_{\chi }$, $M_{H_2}$) that is compatible with the dark matter constraint. Different symbols are used to distinguish the dominant annihilation final states. The dashed (red) line shows the resonance condition: $2M_{\chi }=M_{H_2}$.

Figure 2

The region in the plane ($|g_s|$,$\sin \alpha$) that is compatible with the dark matter constraint. Different symbols are used to distinguish models below, above and on the resonance.

Figure 3

The region in the plane ($M_{\chi }$, $|g_s\sin \alpha |$) that is compatible with the dark matter constraint. Different symbols are used to distinguish models below, above and on the resonance.

Figure 4

The Feynman diagrams that contribute to $\chi \chi \to H_1{H}_2$.

Figure 5

The region in the plane ($M_{\chi }$, $|g_s{\lambda }_4|$) for models compatible with the dark matter constraint in which the dark matter annihilates dominantly into the final state $H_1{H}_2$. Different symbols are used to distinguish models with values of $\sin \alpha$ larger or smaller than 0.01.

Figure 6

The spin-independent direct detection cross section as a function of the dark matter mass for two different values of $M_{H_2}$: 500 GeV (blue squares), 900 GeV (red crosses). The green solid line shows the current bound from the XENON100 experiment while the dashed line displays the expected sensitivity of XENON1T.

Figure 7

The spin-independent direct detection cross section as a function of the dark matter mass for our set of models. Different symbols are used to distinguish models below, above and on the resonance. The green solid line shows the current bound from the XENON100 experiment while the dashed line displays the expected sensitivity of XENON1T.

Figure 8

The reach of current and future direct detection experiments in the plane ($M_{\chi }$, $g_s\sin \alpha$) for models below (left) and above (right) the resonance. The convention is as follows: blue squares for models that are currently excluded by the XENON100 bound, red crosses for models with a ${\sigma }_{\mathrm{SI}}$ within the expected sensitivity of XENON1T, and green circles for models with a ${\sigma }_{\mathrm{SI}}$ below the expected sensitivity of XENON1T.

Figure 9

The region in the plane ($M_{\chi }$, $M_{H_2}$) that is compatible with the XENON100 bound and the dark matter constraint. Different symbols are used to distinguish the dominant annihilation final states. The red band illustrates the resonance region.

Figure 10

The dark matter annihilation rate today, $\sigma v$, versus the dark matter mass for our set of models. Different symbols are used to distinguish the dominant annihilation final states.

Figure 11

Models with an unusually large (black stars) or small (blue squares) $\sigma v$ in the plane ($M_{\chi }$, $M_{H_2}$). The lines $2M_{\chi }=M_{H_2}$ (resonance), $2M_{\chi }=M_{H_1}+M_{H_2}$ and $M_{\chi }=M_{H_2}$ are also shown.

Figure 12

A scatter plot of the equilibrium parameter (left) and the neutrino flux (right) versus the dark matter mass. Models which are excluded by the current XENON100 bound are shown as blue squares; those that are not are shown as orange crosses.

Figure 13

Models in the plane ($M_{\chi }$, $M_{H_2}$) that are consistent with the dark matter constraint and with the XENON100 bound for the general case ($g_p\ne 0$). Different symbols are used to distinguish the dominant annihilation final states. The red band illustrates the resonance region.

Figure 14

A scatter plot of the spin-independent direct detection cross section versus the dark matter mass. Models above (yellow circles), below (blue sqaures) and on the resonance (red crosses) are differentiated. The current bound from XENON100 is also shown (solid line) as well as the expected sensitivity of XENON1T (dashed line).

Figure 15

Models in the plane ($|g_s|$, $|g_p|$) that are consistent with the dark matter constraint. Different symbols are used to distinguish their direct detection status. Models that are already excluded by XENON100 are shown as green circles, those that are within the sensitivity of XENON1T with orange crosses, and those with a spin-independent cross section below the sensitivity of XENON1T as blue squares.

Figure 16

Models in the plane ($|g_s\sin \alpha |$, $|g_p\sin \alpha |$) that are consistent with the dark matter constraint and with the XENON100 bound. Models above, below and on the resonance are differentiated.

Figure 17

A scatter plot of the dark matter annihilation rate versus the dark matter mass for models below the resonance (left) and above it (right). Different symbols are used to distinguished the value of $g_p\sin \alpha$ (left) or $g_p$ (right).

Figure 18

Left: A scatter plot of the equilibrium parameter versus the dark matter mass. Right: A scatter plot of the neutrino flux versus the dark matter mass.

Figure 19

The muon flux versus the dark matter mass. Blue squares (orange crosses) denote points (not) excluded by the XENON100 bound. The current bound from IceCube-DeepCore [31] is also shown as a solid line.