Complex sentence: Ordinary (baryonic) matter interacts strongly by way of radiation whereas dark matter particles, such as WIMPs for example, do not; both affect the oscillations by way of their gravity, so the two forms of matter will have different effects.
Split into simpler sentences: Ordinary (baryonic) matter interacts strongly with radiation whereas dark matter particles, such as WIMPs for example, do not. Both affect the oscillations by their gravity, so the two forms of matter will have different effects.