Dark matter from ’t Hooft anomaly matching

Light fermions that arise as composite states in confining gauge theories are stable due to fermion number conservation. This leads to dark matter (DM) candidates that behave similarly to elementary DM but where the cosmological stability arises automatically from the accidental symmetries of the theory. We present explicit models based on ’t Hooft anomaly matching conditions where DM is charged under the SM. For example an SU(N) gauge theory with fermions in the adjoint rep and triplet of ${\mathrm{SU}(2)}_L$ gives rise to DM made of multiple “Wino” triplets, while SO(N) gauge theories with $N_F=N-4$ flavors produce neutralinolike systems or SM quintuplets. Compositeness effects are crucial to determine the phenomenology.

Figure 1

Indirect detection constraints for DM triplets annihilation to photons in the Galactic Center. The black line is the next to leading annihilation cross-section [14]. Red and blue regions are HESS exclusion limits [13] respectively for Einasto and NFW DM profiles, rescaled to account for the different numerical abundance. Also shown in dashed brown and green are the projections for DM with core radii 0.5 and 2 kpc extracted from [14]. If the multiplets are degenerate, bounds 8 times stronger apply.

Figure 2

Relic abundance estimate of DM made of ${\mathrm{SU}(2)}_L$ quintuplets for different values of $\mathrm{\Lambda }$. Solid and dashed lines correspond to $\mathrm{\Delta }M/M=0.02$ and $\mathrm{\Delta }M/M=0.1$ respectively.