Dark matter as the source of neutrino mass: theory overview and experimental prospects

Abstract

We review theoretical frameworks in which small neutrino masses arise radiatively through interactions with a dark sector that also accounts for cosmological dark matter (DM). A prototype is provided by scotogenic schemes, that extend the inert Higgs doublet model to include dark fermions. We outline their key features and limitations, discussing the advantages of the revamped scotogenic extension. The phenomenological signatures of fermionic and bosonic scotogenic dark matter are discussed, along with scoto-seesaw models that merge scotogenic and seesaw mechanisms. We also consider scenarios where the dark sector seeds a low-scale seesaw. These frameworks can accommodate dark matter as Weakly or Feebly Interacting Massive Particles (WIMPs or FIMPs). While hidden dark sector models are inherently difficult to exclude, visible dark sector schemes should be confirmed--or ruled out--by forthcoming dark matter, collider, and lepton flavor violation studies.

Figures (61)

• Figure 1: Landscape of possible dark matter candidates, covering an incredibly broad range of masses.
• Figure 2: Complementarity of WIMP dark-matter detection techniques Arcadi:2017kkyFeng:2022rxtBozorgnia:2024pwkBoveia:2022adi. The horizontal forward direction indicates DM annihilation to SM particles, the upward direction indicates DM scattering off-nuclei, whereas the horizontal backward direction denotes DM production via SM particle collisions.
• Figure 3: The $0\nu\beta\beta$ decay amplitude in a general three-neutrino picture versus the degeneracy parameter $\eta$, taken from Lattanzi:2020iik. The blue and magenta branches are the regions allowed by neutrino oscillations deSalas:2020pgw10.5281/zenodo.4726908 for normal and inverted neutrino mass ordering. The current experimental bound $|m_{\beta\beta}|<(36-156)\,$meV at $90\%$ C.L. from KamLAND-Zen KamLAND-Zen:2022tow and the sensitivities on $|m_{\beta\beta}|<(9.0-21)\,$ meV expected at LEGEND-1000 LEGEND:2021bnm and $|m_{\beta\beta}|<(6.1-27)\,$ meV at nEXO nEXO:2021ujk, as indicated by the horizontal bands in light brown, yellow and green, respectively. The vertical grey band is excluded by the $95\%$ C.L. limit $\Sigma_{i}m_{i}<0.120\,\text{eV}$ from Planck Planck:2018vygGerbino:2022nvz.
• Figure 4: Allowed $0\nu\beta\beta$ decay amplitude when one neutrino is massless (see text). The periodic bands in blue and magenta are the current 3$\sigma$ C.L. regions for normal and inverted mass-ordering, respectively. The horizontal bands give the constraints from current experiments: CUORE (cyan, $\braket{m_{\beta\beta}}<0.075-0.350$ eV) CUORE:2020ymk, EXO-200 (magenta, $\braket{m_{\beta\beta}}< 0.093-0.286$ eV) EXO-200:2019rkq, Gerda-II (orange, $\braket{m_{\beta\beta}}<0.079-0.180$ eV) GERDA:2020xhi and KamLAND-Zen (gray, $\braket{m_{\beta\beta}}<0.036-0.156$ eV) KamLAND-Zen:2016pfg. The black horizontal dashed lines are the projected sensitivities of SNO+ Phase-II (0.019 eV) SNO:2015wyx, LEGEND-1000 (0.015 eV) LEGEND:2017cdu, JUNO Zhao:2016brs and nEXO - 10yr (0.0057 eV) nEXO:2017nam.
• Figure 5: The solid (dotted) [dashed] lines delimit the $1\sigma$ ($2\sigma$) [$3\sigma$] $m_{\beta\beta}$ regions allowed by oscillations, and also the predictions of two flavor schemes taken from Barreiros:2020gxu. Vertical bars in mid-panels indicate 95%CL $|m_{\beta\beta}|$ upper bounds from KamLAND-Zen 400 KamLAND-Zen:2016pfg, GERDA GERDA:2020xhi, CUORE CUORE:2020ymk and EXO-200 EXO-200:2019rkq.