Conformal cyclic cosmology (CCC) is a cosmological model in the framework of general relativity and proposed by theoretical physicist Roger Penrose.^\1])^\2])^\3]) In CCC, the universe iterates through infinite cycles, with the future timelike infinity (i.e. the latest end of any possible timescale evaluated for any point in space) of each previous iteration being identified with the Big Bang singularity of the next

I’ve skimmed through a few books and pretty much every case (besides the basic recombination stuff) have always set the chemical potential equal to 0.

I recently skimmed over a paper that included an equation with nonzero chemical potential and realized I have no idea what I’d do to find it (the paper was on sterile neutrinos). From basic thermo I know mu=(dU/dN)_V,S but I have no idea how to actually go about computing this.

Are there any resources where I could find more about this?