2.4. Alternative Particle Models for Dark Matter
If all the above, more conventional, particle candidates for dark matter fall by the wayside, theorists have more exotic candidates in their back pockets [93, 94, 95]. For example, there could be interacting massive fermions that resemble warm dark matter, should that be required. Alternatively, there could be interacting scalar dark matter. One of these possibilities might become interesting if the cold dark matter paradigm fails.