GLYPH<Minus> 5 GLYPH<Minus> 4 GLYPH<Minus> 3 GLYPH<Minus> 2 GLYPH<Minus> 1 0 0.01 0.02 0.03 0.04 Density for repulsive fermions PSfrag replacements n/mT µ/T n$_{c}$ FIG. 18: Density of the repulsive fermionic case as a function of µ/T . of the fermion case: At this point c ( − 1 . 3) ≈ 0 . 11. The ratio η/s is shown in Figure 23. It has a minimum at µ/T = − 1 . 72 near the critical point and in the physical region: Recall, the region µ/T > − 1 . 45 is unphysical. Let us suppose the gas consists of multiple species of particles labeled by the index “a”, of mass m$_{a}$ , chemical potential µ$_{a}$ , and statistical parameter s$_{a}$ = ± 1. Introduce 38 IX. MULTIPLE SPECIES OF PARTICLES n$_{c}$ = 0 . 125 mk$_{B}$T 2 π ℏ 2 ⇐⇒ T$_{c}$ ≈ 8 . 0 ϵ$_{F}$ (100) η s ≥ 8 . 85 ℏ 4 πk$_{B}$ (101)